sign in sign up
<<
Home , Allegheny Formation, Berea Sandstone, Berry Mountain, Bloomsburg Formation, Bluestone Formation, Catskill Formation

Geology of the West-Central Part of the Southern Field and Adjoining Areas,

GEOLOGICAL SURVEY PROFESSIONAL PAPER 602

Geology of the West-Central Part of the Southern Anthracite Field and Adjoining Areas, Pennsylvania

By GORDON H. WOOD, JR., J. PETER TREXLER, and THOMAS M. KEHN

GEOLOGICAL SURVEY PROFESSIONAL PAPER 602

A study of part of one of the classic areas of geology and of the surrounding region

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1969 DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary

GEOLOGICAL SURVEY William T. Pecora, Director

Library of Congress catalog card No. GS 68-298

For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 CONTENTS

Page Page Abstract______1 Continued Introduction. ______3 System Continued Physical features.______4 Continued Present investigation.______5 of the Pocono Formation._____ 63 Previous work______6 Age and correlation of the Pocono Forma­ Acknowledgments______7 tion. ______65 Principal geologic featurea______7 Mississippian and rocks____-____--_ 65 Stratigraphy ______Mauch Chunk Formation____-____-____--_--_ 65 System______Lower member.______65 Martinsburg Shale______Middle member.______66 Ordovician- -______9 Upper member-______67 Silurian System______9 Sections of the . _ 68 Tuscarora .______10 Deposition of the Mauch Chunk Formation. 68 .______11 Age of the Mauch Chunk Formation______70 Bloomsburg Red Beds______13 Pennsylvanian System ______--___---_--_-_- 70 Wills Creek Shale_-_____--_-______15 -______-_------_-__ 70 Tonoloway -______16 Tumbling Run Member------_----_-.--- 70 Silurian and rocks______16 Schuylkill Member ______73 Keyser Limestone.______16 Member______74 Devonian System.______17 Thickness of the Pottsville Formation..-.- 77 .______18 Deposition of the Pottsville Formation-___ 77 Oriskany Group ______22 Age and correlation of the Pottsville Forma­ Shriver Chert.______22 tion. ______-___-_------_--_------78 Pre-Ridgeley unconformity.______24 Llewellyn Formation.______-_____-----_-_- 79 .__--_-_-_-_-______24 deposits.______-----___-----_--- 82 Post-Ridgeley unconformity______26 Talus. ______- - 82 Needmore .______26 Alluvium. ___-______-_------_------82 Selinsgrove Limestone.___-_--____--______26 Structure.______-__------84 Hamilton Group______28 Structural features formed during the Taconic Marcellus Shale.______28 .______-_------84 .______29 Structural features formed during the Acadian Lower shale and sandstone member. _ _ 29 orogeny.------84 Montebello Sandstone Member. 32 Upper shale member.______35 Structural features formed during the Appalachian 85 Thickness of the Mahantango Forma­ orogeny._____------85 tion... ______36 Folds 85 Depositional environment, age, and Broad Mountain anticlinorium. 86 correlation of the Mahantango For­ New Bloomfield anticlinorium__--_. 87 mation. ______36 Minersville synclinorium _..... 87 Susquehanna Group ______37 ______----_---. 88 Trimmers Rock Sandstone.______37 Hooflander Mountain . 88 Devonian and Mississippian rocks.______41 Frackville anticline.------88 .______41 West West Falls anticline..--- 88 Irish Valley Member.______:_____.._ 42 Branchdale anticline-______--. 89 Damascus Member.______45 Big Lick Mountain anticline. _. 89 Honesdale Sandstone Member_-_____-_. 48 Joliet anticline.______---. 89 Cherry Ridge Member.______51 Roedersville anticline. _____-_. Buddys Run Member.______53 - ______------_----- 90 Spechty Kopf Member.______55 Heckscherville . ___--_- 90 Thickness of the Catskill Formation______57 Little Mountain syncline. _____ 90 Pre-Pocono unconformity.______57 North Little Mountain syncline. 90 Mississippian System______58 Deep Creek syncline-_____--_- 91 Pocono Formation ______59 Donaldson syncline-______-- 91 Beckville Member.______59 Tremont syncline-______--_- 91 Mount Carbon Member.______62 Dauphin syncline-___--__----- 92 Thickness of the Pocono Formation.______63 Pine Grove syncline ___.__-_ 92 nx IV CONTENTS

Page Pago Structure Continued Economic geology.______117 Structural features formed during the Appalachian --.-----.------__---_---__----- 117 orogeny Continued History and methods of mining______117 Faults______93 Extent of mine workings______118 Low-angle folded thrust and underthrust Condition of mine workings____-______-______118

ILLUSTRATIONS

[Plates are in pocket] PLATES 1-3. Columnar sections of Pennsylvanian rocks: 1. North trough of Minersville synclinorium. 2. Broad Mountain and Heckscherville syncline. 3. South trough of Minersville synclinorium. 4. Tectonic map of west-central part of Southern Anthracite field. CONTENTS Page FIGURE 1. Index map of Anthracite region and quadrangles______-______-___----- 4 2. Index showing quadrangle names and areas of responsibility______5 3. Isopach map of Bloomsburg Red Beds______-_--_-___--_------14 4. Columnar sections of Silurian and Devonian rocks from base of Tonoloway Limestone to top of Selinsgrove Limestone______--_------__ 18 5-11. Isopach maps: 5. Tonoloway Limestone______-______-__------_ 20 6. Keyser Limestone and Coeymans and New Scotland Members of Helderberg Formation______.______-_-__---_-__---_------21 7. Mandata Member of Helderberg Formation.______22 8. Shriver Chert______23 9. Ridgeley Sandstone______25 10. Needmore Shale______._-_-__--___-_--_---_-_ 27 11. Selinsgrove Limestone______-______-___------_------28 12. Columnar sections of Marcellus Shale______-____------_--_------30 13. Isopach map of Marcellus Shale.l______---__--_-----_---_ 31 14. Columnar sections of Mahantango Formation______-_---__------__------32 15-18. Isopach maps: 15. Lower shale and sandstone member of Mahantango Formation..______33 16. Montebello Sandstone Member of Mahantango Formation.______34 17. Upper shale member of Mahantango Formation______35 18. Mahantango Fonnation______36 19. Columnar sections of Trimmers Rock Sandstone______------_------_------39 20. Isopach map of Trimmers Rock Sandstone______------_------40 21. Columnar sections of Irish Valley and Damascus Members of Catskill Formation_____ 43 22, 23. Isopach maps: 22. Irish Valley Member of Catskill Formation.______44 23. Damascus Member of Catskill Formation-______46 24. Columnar sections of Honesdale, Cherry Ridge, and Spechty Kopf Members of Catskill Formation-______-__-___-_-_----__-- 49 25-30. Isopach maps: 25. Honesdale Sandstone Member of Catskill Formation______50 26. Cherry Ridge Member of Catskill Formation.______52 27. Buddys Run Member of Catskill Formation.______54 28. Spechty Kopf Member of Catskill Fonnation______.___ 56 29. Catskill Formation______57 30. Members of Catskill Formation older than Spechty Kopf Member______58 31. Columnar sections of Pocono Formation.______60 32-34. Isopach maps: 32. Beckville Member of Pocono Formation______61 33. Mount Carbon Member of Pocono Formation______62 34. Pocono Formation______64 35. Columnar sections of Mauch Chunk Fonnation____.______69 36-38. Isopach maps: 36. Tumbling Run Member of Pottsville Formation______71 37. Schuylkill Member of Pottsville Formation______73 38. Sharp Mountain Member of Pottsville Formation.______75 39. Contour map of maximum diameter of pebbles and cobbles in the Sharp Moun­ tain Member of the Pottsville Formation______76 40. Isopach map of Pottsville Formation. ______77 41. Orientation of joints in the report area, with reference to regional plunge and strike of structural grain______111 42. Isocarb map of the west-central part of Southern Anthracite field.______136 VI CONTENTS TABLES

Page TABLE 1. Observed ranges of plant in the Llewellyn Formation and upper part of the Pottsville Formation.______83 2. Production of anthracite from the Anthracite region, Southern Anthracite field, and report area______120 3. Average thickness and range in thickness of Llewellyn and Pottsville coal beds_ __..__ 123 4. Physical properties of semianthracite and anthracite from the west-central part of the Southern Anthracite fleld_-__---_----_-_-----_---_--_----_------_-_-__-.-- 131 5. Chemical analyses of bed samples from the west-central part of the Southern Anthra­ cite field.--_.___.______.___._._.______.- 132 6. Chemical analyses of breaker samples from the west-central part of the Southern Anthra­ cite field___.__.______-______.______._____ 134 7. Average chemical analyses of breaker samples from the west-central part of the Southern Anthracite field______._._-__-.__ 135 GEOLOGY OF THE WEST-CENTRAL PART OF THE SOUTHERN ANTHRACITE FIELD AND ADJOINING AREAS, PENNSYLVANIA

By GORDON H. WOOD, JR., J. PETER TREXLER, and THOMAS M. KEHN

ABSTRACT Limestone, 0 to 200 feet thick, was deposited with apparent This report describes an area of about 450 square miles in conformity on the Tonoloway. Definite Early Devonian sedimentation commenced with the Berks, Dauphin, Lebanon, Northumberland, and Schuylkill Helderberg Formation, 0 to 100 feet thick, which consist" of Counties of the Anthracite region, east-central Pennsylvania. the gray Coeymans and New Scotland Limestone Members and The stratigraphy and structure of about 100 square miles of the Mandata Member (shale). The Helderberg is overlain suc­ the west-central part of the Southern Anthracite field and ad­ cessively by upper Lower Devonian rocks of the dark-^ray jacent areas of the Klingerstown, Lykens, Minersville, Pine Shriver Chert, 0 to 80 feet thick, and the gray Ridgeley Sand­ Grove, Swatara Hill, Tower City, Tremont, and Valley View stone, 0 to 60 feet thick. Stratigraphic relations between the 7^-minute quadrangles are described in detail. Shriver and Ridgeley are conformable in the northwestern part The area, which is a part of the , lies of the area, but the Shriver and all subjacent Lower Devonian in the Delaware-Susquehanna Rivers segment of the middle and Upper Silurian rocks down to and including the upper part section of the Valley and Ridge or folded Appalachian province. of the Bloomsburg Red Beds are truncated in the central and Tributaries of the drain the central and southern parts by a pre-Ridgeley surface. This surface western parts of the area; the eastern part is drained by the developed because the Auburn promontory was uplifted south of . Resistant strata support a series of sinuous the report area, following Shriver deposition. After eroMon, linear-strike mountain ridges separated by strike valleys which the region subsided slightly, the sea transgressed southeast­ have been eroded in less resistant strata. ward toward the promontory, and sediments of the Ridpsley Middle Ordovician to Upper Pennsylvanian rocks that aver­ accumulated. age about 24,500 feet thick crop out in the area. At many places, A minor rejuvenation of the Auburn promontory in the thin deposits of alluvium, soil mantle, and talus of Quaternary southern part of the area forced the sea to retreat northwest­ age overlie an erosion surface that has been cut into these rocks. ward in late Early or early Middle Devonian time. After the Except for 700 to 1,800 feet of deltaic red beds of early Late sea regressed, the upper beds of the Ridgeley were slifhtly Silurian age, the lower 8,000 to 9,600 feet of the se­ eroded at most places, and locally the formation was com­ quence accumulated in the sea. Marine waters regressed about pletely removed. The sea then transgressed from the north­ the middle of Late Devonian time, and the remainder of the west upon this erosion surface, and the dark-gray Needmore Paleozoic sequence was deposited under continental conditions. Shale, 0 to 100 feet thick, was deposited. At the end of Needmore The upper 1,000± feet of the Martinsburg Shale of Middle deposition the region adjacent to the promontory was rgain and Late Ordovician age underlies the southeastern part of the slightly elevated, and the Needmore was removed from the area, but is everywhere covered by talus. Where the Martins- southern part of the area. The sea again transgressed south­ burg is exposed south and east of the area, rocks in the upper eastward, and the gray Selinsgrove Limestone, 20 to 100 feet part of the formation consist of interbedded marine gray shale, thick, accumulated. Successively, the dark-gray to black Mar- siltstone, sandstone, and limestone. After deposition of the cellus Shale, 60 to 700 feet thick, and the Mahantango For­ Martinsburg, the sea regressed westward, and the uplifting, mation, 1,200 to 2,000 feet thick, of late Middle Devoniar age folding, faulting, and erosion of the took were laid down on the Selinsgrove. The gray Montebello fc'ind- place in Late Ordovician time. stone Member, medial unit of the Mahantango, records a major At the end of the Taconic orogeny in earliest Silurian time rejuvenation of the Auburn promontory. the sea transgressed southeastward and deposited about 400 feet About the beginning of the Late Devonian or late in the Middle of the grayish detritus of the . This detri­ Devonian, mountain making that heralded the tus was eroded from a highland that lay to the southeast. The commenced southeast of the area and gradually uplifted a land- overlying Clinton Formation of Middle Silurian age grades mass of considerable size. Detritus derived from the land'^ass downward into the Tuscarora and consists of 2,300± feet of was transported northwestward to the sea and distributed by red and gray detritus that was also derived from the highland. currents over a region much larger than the area of this rer>ort. During early Late Silurian time the sea regressed northwest­ It was consolidated into the Trimmers Rock Sandstone, l.S'X) to ward, and 700 to 1,800 feet of the Bloomsburg Red Beds was 2,400 feet thick. As this influx of sediment gradually exceeded laid down upon the Clinton in a deltaic environment. After dep­ the capacity of the subsiding basin, the sea slowly regressed osition of the red beds the sea again transgressed towards the northwestward with many reversals. During regression, a southeast in middle Late Silurian time, and the varicolored sequence of intertonguing gray marine and red continental Wills Creek Shale, 0 to 400 feet thick, and the gray Tonoloway clastic rocks accumulated that ranges in thickness from about Limestone, 0 to 400 feet thick, accumulated successively. In 200 to 2,250 feet. These marine and continental strata are the latest Silurian and earliest Devonian time, the gray Keyser Irish Valley Member of the Catskill Formation. Near the end GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA of Irish Valley sedimentation, or early in the deposition of over­ vanian age rests conformably on the Schuylkill Member and lying sediments, the sea regressed, and almost all succeeding consists of 100 to 315 feet of beds similar to those of the Devonian, Mississippian, and Pennsylvanian sediments are con­ Tumbling Run. Pebbles and cobbles in the upper member of the Mauch Chunk Formation and in the Tumbling R-^n and Sharp tinental deposits. From middle Late Devonian to Early Mississippian time the Mountain Members of the Pottsville Formation contain the red and gray continental beds of the middle and upper parts of sedimentary record of the two earliest pulsation? of the Appa­ the Catskill Formation were laid down. This sequence in the lachian orogeny in Pennsylvania. northern part of the area is divided into the predominantly red The Llewellyn Formation of late Middle and Late Pennsyl­ Buddys Run Member, 4,200 to 4,800 feet thick, and the overlying vanian age reaches its maximum known thickness of about 3,500 gray and red Spechty Kopf Member, 0 to 1,000 feet thick. In feet in the area. It is composed of grayish sandstone, siltstone, the southern part it is divided, in ascending order, into the pre­ shale, and and numerous thin to thick beds of an­ dominantly red Damascus Member, 2,600 to 4,650 feet thick; thracite. Sediments of the formation seem to have been laid down the gray and red Honesdale Sandstone Member, 0 to 700 feet on a large poorly drained flood plain or coastal plain that lay thick; the predominantly red Cherry Ridge Member, 700 to 1,800 northwest of a generally low but in places rejuvenated mountain feet thick; and the gray and red Spechty Kopf Member, 0 to belt The plain was dotted by many swamps during deposition; 2,400 feet thick. some of these covered hundreds and perhaps thousands of square At least three phases of the Acadian orogeny of the Late miles. Deposits of vegetation that accumulated in these swamps Devonian and Early Mississippian age are recorded by rocks were partly decomposed to peat and eventually buried by suc­ of the Catskill Formation. The climaxes of these phases are ceeding layers of sediment. The peat gradually altered to lignite marked by conglomerates in the Honesdale and the lower part and then was metamorphosed through the bitumirous-coal series of the Spechty Kopf and by an angular unconformity that bevels to anthracite. Early metamorphic changes seenr to have been the Spechty Kopf. This unconformity shows that in Early Missis­ caused by the pressure of increasing overburden., whereas later sippian time, deformation associated with the orogeny advanced changes were primarily due to horizontal pressures related to folding and faulting, and secondarily, to pressure from increas­ into the area from the southeast. The Spechty Kopf is overlain unconformably by the Beckville ing overburden. Member of the Pocono Formation of Early Mississippian age The geologic structure is complex. Folding and faulting related which ranges in thickness from about 300 to 800 feet and con­ to three periods of mountain building affected tl e area. During sists of a gray basal conglomerate, gray finer clastic rocks, and Late Ordovician time the southeastern part of the area was a few thin beds of coal. The Mount Carbon Member of the folded by forces of the Taconic orogeny. In Early Mississippian Pocono Formation conformably overlies the Beckville and has a time, forces of the Acadian orogeny compressed the rocks of the similar . It ranges in thickness from about 400 to 1,000 area into a series of large-amplitude folds which trend north­ feet. The basal conglomerates of these members seem to represent east, and, in the latter part of the Paleozoic Era during the clastic detritus that was eroded from periodically rejuvenated Appalachian orogeny, the area was intensively deformed. Rela­ parts of the Acadian Mountains. tions of folds and faults formed during the orogeny indicate that mountain building commenced southeast of the area and that Red and gray beds of the Upper Mississippian and Lower it gradually advanced towards the northwest with increasing Pennsylvanian Mauch Chunk Formation, 3,000 to 7,500(?) feet vigor. By the end of the orogeny a multitude of complexly inter­ thick, succeed the Pocono conformably. Three informal members related structural features had formed. Chief among these were are recognized in the Mauch Chunk. The upward decrease in a series of northeast-trending anticlinoria and synclinoria, nu­ grain size of the interbedded red and gray detritus of the lower merous subsidiary doubly plunging en echelon foMs, a multitude member, 400 to 800 feet thick, records the gradual reduction of of low-angle folded and nonfolded thrust faults, numerous high- the Acadian Mountains. Most of the red beds of the Mauch Chunk are included in the middle member, which is 2,000 to angle reverse faults, and a few large tear faults. Most structural features in the report area formed during the 6,000 feet thick. These beds are composed largely of clay, silt, Appalachian orogeny. The largest of these are the Minersville and fine sand. The fine grain size, plant fossils, and associated synclinorium, which splits westward into two subsynclinoria, sedimentary features in these beds suggest that the middle mem­ and the Broad Mountain and New Bloomfield anticlinoria. The ber accumulated on flood plains or on a coastal plain at a con­ subsidiary anticlines and synclines of these composite fold siderable distance from a reduced source area. Clay- to cobble- sized detritus in interbedded red and gray beds of the upper systems are mainly on the limbs and in the troughs. They range in length from a few inches to many miles and in amplitude member, 400 to 900 feet thick, indicate that the source area to from several inches to thousands of feet. Th^ principal sub­ the southeast was uplifted during latest Mississippian time. This sidiary folds are the Branchdale, Eisenhuth Pun, Frackville, uplifting marked the beginning of the Appalachian orogeny. Hooflander Mountain, Joliet, Mine Hill, Peeked Mountain, The deposition of red beds ceased at the beginning of the Powder Hill, Roedersville, and West West Falls anticlines and Pennsylvanian in the southern part of the area but continued the Beury, Dauphin, Deep Creek, Donaldson, Heckscherville, for some time thereafter to the north. Red sediments of the Mauch Chunk were succeeded by intertonguing relations of 800 New Boston, and Pine Grove synclines. Most lo^g synclines are closed, asymmetric, and V-shaped in their central parts; in to 1,500 feet of gray fine- to coarse-grained sediments of the Pottsville Formation, which is divided, in ascending order, into contrast, large anticlines are broad, open, and more nearly the Tumbling Run, Schuylkill, and Sharp Mountain Members. symmetrical. Near their ends the cross sections of many synclines are U-shaped, whereas those of most anticlines are inverted The Tumbling Run consists of 275 to 600 feet of grayish pebble and cobble conglomerate, sandstone, and siltstone beds and sev­ V-shaped. eral beds of anthracite. Although cobble conglomerates are vir­ The Minersville synclinorium and the Broa^ Mountain anti- tually absent, the conformably overlying 300- to 700-foot thick clinorium, which have amplitudes of 10,000 to 15,000 feet, are Schuylkill Member of late Early Pennsylvania age is lithologi- the largest structural features. Most subsidiary folds and faults cally similar. The Sharp Mountain Member of Middle Pennsyl­ are on the limbs of these large composite fcld systems. The INTRODUCTION main trough and the south trough of the synclinorium separate in strip pits and roadcuts. Because of these exposures, generally upright strata to the north from generally overturned both natural and manmade, and the large amount of strata to the south. Bock sequences in the main trough and in data provided by mine maps and cross sections, the re­ the north and south troughs of the synclinorium were greatly thickened during folding. The development of the Mauchono port area is one of the better places in the central part of and Pottchunk faults seems to be related to this thickening. the Appalachian Mountains to study the geometry and Low-angle thrust faults formed on the north limb of the syn­ relations of folds and faults and to observe and inter­ clinorium and across the crest of the anticlinorium before exten­ pret the vagaries of "coal-measure" deposition. sive folding took place as the result of differential transmission Although anthracite had been mined in the area of force through strata of differing eompentencies. The thick, rather competent strata of the Pocono and Pottsville Forma­ for 150 , the area probably contains as much as tions were more capable of transmitting force than were the 50 percent of the remaining reserves of coal in the intervening thick incompetent strata of the Mauch Chunk For­ Southern Anthracite field, and it probably contains mation. During the early stages of folding, these competent greater remaining reserves than any other comparable strata tore loose from the less competent strata and moved dif­ ferentially on the Pottchunk fault above and the Mauchono fault area in the Anthracite region. The actual tonnage of below. As faulting progressed, the upper plate of the Pottchunk coal produced is unknown because records that were kept fault was broken into imbricated blocks by the successive devel­ during the early period of mining were chiefly for com­ opment of the Hans Yost, Dyer Bun, Jugular, and Mine Hill mercial district or county rather than for mines, because low-angle trust faults. The area was then more tightly com­ a considerable unreported tonnage was produced during pressed ; many subsidiary folds formed on the limbs of the anti- the 1930's by independent or "bootleg" miners, and be­ clinoria and synclinorium; the planes of the Mauchono and Pottchunk faults were folded; and numerous high-angle reverse cause official tonnage records are maintained by the faults, such as the Newtown, South Newtown, Tremont, and amount of coal cleaned at preparation or breaker plants, Bed Mountain, formed. As compression increased, the south limb by county, and by coal field, and only in some instances of the Minersville synclinorium was overturned, perhaps into a by mine. It is estimated that about 318 million tone of nappe, and the low-angle Sweet Arrow and Blackwood faults formed. anthracite valued at about 1.1 billion dollars was pro­ The west-central part of the Southern Anthracite field has duced in the area from 1790 to 1960. yielded about 318 million tons of anthracite valued at about $1.1 Maps and structure sections of the eight described billion. Approximately 0.6 percent of the energy consumed in quadrangles do not appear in this report. They have the United States before 1960 was from coal produced in the been published by the U.S. Geological Survey as eight area. Nearly 7.6 billion tons of anthracite is estimated to have 1:24,000-scale Geologic Quadrangle maps with 16 struc­ underlain the area before mining began. Of this original con­ ture sections (Trexler and Wood, 1968a-c; Wood, l^S; tent of anthracite, about 6.3 billion tons is estimated to have Wood and Kehn, 1968a, b; Wood and Trexler, 19f8a; been in beds more than 42 inches thick, and about 5.7 billion and Wood and others, 1968) and two Miscellaneous Geo­ tons of the original content lay within 3,000 feet of the surface. logic Investigations maps containing seven 1:12,000- About 2.6 billion tons of anthracite was believed (1961) to be recoverable in the future within 3,000 feet of the surface; 1.9 scale coal maps and 44 structure sections (Wood and billion tons of this recoverable anthracite is estimated to be Trexler, 1968b, c). In this paper the geologic maps are in beds more than 42 inches thick. hereafter referred to by their "GQ" number. The rerder should consult these 15 geologic and coal maps and 60 INTRODUCTION structure sections in conjunction with this paper to de­ rive maximum benefit from all. This report describes the geology of the Klingers- The geology of two small areas in the Southern An­ town, Lykens, Minersville, Pine Grove, Swatara Hill, thracite field has been treated in preliminary reports Tower City, Tremont, and Valley View T1/^-minute published by the U.S. Geological Survey (Wood and topographic quadrangles in Berks, Dauphin, Lebanon, others, 1958; Wood and others, 1962). Eevised maps Northumberland, and Schuylkill Counties (fig. 1). The and cross sections of these two areas are included in area of these quadrangles, about 450 square miles, in­ the Miscellaneous Geologic Investigations maps men­ cludes the west-central part of the Southern Anthracite tioned above (Wood and Trexler, 1968b, c). The stratig­ field of the Anthracite region of eastern Pennsylvania. raphy and nomenclature of some rock units and the The report is a result of investigations by geologists of the U.S. Geological Survey from 1953 to 1963. structural development of the Anthracite region 1 ave The structural geology of the report area is com­ been described in several short papers (Wood and otHrs, plex and is characterized by numerous folds whose 1956; Arndt and others, 1959; Arndt and Wood, 1960; limbs are broken by faults. Natural outcrops are rare, Wood and Kehn, 1961; Trexler and others, 1962; Wood commonly small, and probably amount to less than 1 and others, 1962; Arndt and others, 1962). The con­ percent of the land surface; within the Southern An­ clusions reached in these short papers are incorporated thracite field, however, rocks are exposed at many places in this report. GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA

30' 15' 76°00' 45' 30'

L Y C 0 M I /N G """~"7// /

Quadrangles described in detai in this report

FIGUKE 1. Index map of the Anthracite region, east-central Pennsylvania, and location of quadrangles.

PHYSICAL FEATURES quadrangle. Tributaries of the Susquehanna River drain the remainder of the area. The area is in the Delaware-Susquehanna Rivers seg­ ment of the middle section of the Valley and Ridge or The mountain ridges are held up by gently to steeply folded Appalachian province of Fenneman (1938). dipping sandstone and conglomerate units, whereas the Many northeastward-trending mountain ridges and val­ valleys are chiefly underlain by shale and siltetone units. leys cross or extend into the area from the surrounding Altitudes in the valley bottoms generally range from region. The Schuylkill River drains much of the Miners- 500 to 900 feet above sea level and on the maintain tops ville quadrangle and a small part of the Swatara Hill from 1,200 to 1,850 feet above sea level. INTRODUCTION The rocks are complexly folded and faulted. Region­ ally, the fold pattern plunges to the northeast; many of the smaller folds and some of the larger die out within the area. Many ridges and valleys double back and forth in a series of pointed zigzags, thereby outlining the structural configuration of the plunging fold pattern. The names of the ridges change at each sharp bend and in places at water gaps. The most persistent of these ridges is underlain by the Pocono Formation; others are underlain by the Tuscarora Sandstone, the Clinton For­ mation, the Montebello Sandstone Member of the Ma- hantango Formation, and the Pottsville Formation. The only deep wind gap is in Fisher Ridge northwest of Klingerstown. However, shallow and incipient wind gaps are scattered throughout the area. has cut a large in Second Mountain north of FIGURE 2. Index showing quadrangle names and area? of Pine Grove and another in Sharp Mountain south of responsibility. Geologic mapping by U.S. Geological Surety : Tremont. The gap of Lorberry Creek in Sharp Moun­ Gordon H. Wood, Jr., 1953-60; J. Peter Trexler, 1953-58, tain a few miles west of Tremont is similar in size and 1960; Thomas M. Kehn, 1954-56, 1958-59; Andy Yelenosky, depth. Mill Creek has cut an impressive gap through 1953-56; Julian Soren, 1954-57. Second Mountain north of Suedberg; by contrast, the of each coal map (Wood and Trexler, 1968 b, c), many gaps eroded in Sharp Mountain by its tributaries, Fish­ structure sections were plotted utilizing all available ing, Black Spring, and Gold Mine Creeks, are consider­ subsurface information. Some of these structure sections ably smaller. Rattling Creek flows through a small gap are included in GQ-689, 690, 691, 692, 698, 699, 700, and in Berry Mountain south of Lykens, and Bear Creek 701 and Wood and Trexler (1968b, c). Geologic (?ata has eroded a similar gap through Big Lick Mountain outside the coal field were delineated on the aerial photo­ north of the same town. From a distance, the most im­ graphs and subsequently transferred by similar methods pressive gap is that cut by Pine Creek through Mahan- to the 1: 20,000-scale topographic bases used for compi­ tango Mountain south of Klingerstown. lation of the quadrangle maps. These latter maps v^re PRESENT INVESTIGATION completed by transferring selected data from the coal maps with a vertical projector. The study of the geology of the Southern Anthracite This report was prepared by Wood from 1961 to 1964. field began in the summer of 1953 and continued without He compiled all maps and illustrations except the Kling­ interruption to 1963. The investigation has been under erstown, Lykens, and Valley View 7^-minute quad­ the direction of Gordon H. Wood, Jr., and has included rangles and the Lykens quadrangle coal map. Trexler at various times, J. Peter Trexler, Thomas M. Kehn, hastened report completion by preparing the above- Julian Soren, and Andy Yelenosky. Areas of mapping listed map exceptions and by writing a report (1964) on responsibility are shown in figure 2. the western part of the area. Kehn was responsible for Aerial photographs, at a scale of 1:20,000, were used much of the fieldwork and preliminary office compila­ for geologic mapping because they show more of the tion of data and contributed materially to interpre­ features related to mining than do topographic maps tation of stratigraphic and structural data. and because lithologic units and structural features too Charles B. Read examined numerous plant collections small to be identified on topographic maps can be traced and determined that floral sequences were missing lo­ through areas of heavy vegetation, mining activity, and cally. This knowledge aided in identification and inter­ farming. Within the anthracite field, geologic data were pretation of folded thrust faults at several places. Wal­ delineated on the aerial photographs and then trans­ lace de Witt, Jr., and George W. Colton studied the ferred by vertical projector or multiplex to 1:10,000- Devonian stratigraphy and thereby increased the cer­ scale topographic bases used for compilation of the coal tainty of regional correlations of rocks of this age. maps. Mine data obtained from companies, engineers, Harold H. Arndt, geologist in charge of U.S. Geolog­ and individuals were reduced photographically from ical Survey work in the Western Middle Anthracite scales of 1 inch = 100 feet, 1 inch = 300 feet and 1 inch field, cooperated fully with the authors by contributing = 400 feet to the 1:10,000 scale and then combined with pertinent data, ideas, criticisms, and conclusions. I ir- the field data on the coal maps. Before the completion ing many phases of the investigation he worked v^ith 6 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA Southern Anthracite field personnel on problems of Mauch Chunk, and Pottsville Formations of modern mutual interest. nomenclature. PREVIOUS WORK From 1880 to 1895, numerous reports wer^- published by the Second Pennsylvania Geological Survey on the The Anthracite region has been considered by many geology of the report area and the surrounding region. geologists to be an area where the geology is known. Principal among these were: I. C. White's (1882,1883) This belief was based on the assumption that the geol­ reports on the stratigraphy of Devonian and Mississip- ogy was adequately explained in the reports of the First pian rocks in eastern Pennsylvania; Ashbur^er's (1883- (1836-58) and Second (1875-95) Pennsylvania Geolog­ 1885) reports on the Southern Anthracite field; the geo­ ical Surveys. Since the completion of these surveys in logic maps of Dauphin (Sanders, 1881), Berks (Prime 1895, much additional mining and geologic mapping and others, 1884), and Schuylkill (Smith, 1891) Coun­ has made it apparent that the reports of these surveys ties; and the summary descriptions of Silurian, Devo­ do not describe the presently known structural and nian, Mississippian, and Pennsylvanian ro?ks (Lesley stratigraphic complexities. In addition to the reports of and others, 1892-95, p. 721-1915; Smith, 18^5, p. 2072- these surveys, many articles have been published con­ 2146). cerning parts of the region or limited phases of the geol­ In 1893, Stevenson concluded that Pennsylvania an­ ogy, mining, and physiography; numerous others thracite differed from because of differ­ discuss the classification, origin, petrography, trans­ ences in original composition rather than because of portation, and utilization of anthracite, and hundreds metamorphism. Willis (1893) in the same pub­ contain references to the geology and mining industry. lished an analysis of deformation in the Appalachians The following paragraphs list in chronologic order and concluded that the localization of folds in the An­ some of the more important articles contributing to a thracite region was due to initial differences in thickness geologic understanding of the area and the surrounding of sedimentary units. region. Many other reports are cited in the text and are A few years later C. D. White (1900, p. 749-930) listed in the "References." described the stratigraphy, correlated the ccal beds, and The earliest known geologic reference to the area is a determined the floral succession of the Pottsville For­ report on the Swatara mining district (Strong and mation in the report area and elsewhere in the Southern others, 1839). Shortly thereafter, Taylor (1840, 1841) Anthracite field. In 1904, he correlated this formation described the Dauphin syncline and published the from the type locality south westward to and earliest known cross section of folded rocks in the stated that the oldest rocks occurred in the area covered United States. One of these sections illustrated Taylor's by this report and in the southern Appalachians. concept of deformation in the western part of the report Stevenson early in 1904 also correlated th«. Pottsville area. Formation from the area southwestward into Alabama, Eogers in 1843 postulated that the coal of the eastern and in 1906 (p. 65-228), he correlated tH overlying United States formed in a great, gradually sinking "coal-measures" (Llewellyn Formation) of the area swamp adjacent to the sea. He explained the easterly with the "coal-measures" of and decrease in volatile matter as the result of steam and gas . being emitted through cracks as the Appalachian Shortly thereafter, Barrell, in reports published in Mountains were folded. The report area was cited as the locality where the deformation of rocks and devolatil- 1907 and 1913-1914, concluded that the Catakill Forma­ ization of coal were greatest. tion in the vicinity of the report area was deposited on a great delta whose source lay to the east. He also postu­ Bowen (1848) published the first map showing the lated that the Mauch Chunk Formation accumulated on extent of the coal fields of the Anthracite region. a subaerial plain and delta that was dry much of the Within a decade, Rogers (1858a, b), released a geologic year. map of the region and published a comprehensive report The carbon-ratio theory was advanced in 1915 by on Pennsylvania which named many stratigraphic C. D. White. According to White, the eastward decrease units, described most of the principal structural fea­ in volatile matter and the increase in fixed carbon con­ tures, and described some relations between strati- tent of coal in the eastern United States was due to graphic units and structural features in the area. lateral compression by folding and thrusting. The rela­ Nearly 20 years later, Lesley (1876) and Franklin tion between low volatile matter, high fixec1 carbon con­ Platt, and W. G. Platt (1877) renamed some of the tent, and structural complexity in the Southern An­ stratigraphic units that were originally recognized thracite field was cited by White as proving his theory. by Rogers. Principal among these were the Pocono, In 1925, White published a comprehensive summary PRINCIPAL GEOLOGIC FEATURES showing that the rank of coal is not due to original and others, 1961, 1962; Wood and Kehn, 1961; Wood composition or depth of burial, but is due to progressive and others, 1962). Two of these reports describe, the regional carbonization as the result of lateral compres­ geology of small parts of the report area (Wood and sion. Turner, in 1934, supported White by postulating others, 1958,1962). that carbonization in the southern part of the Anthra­ cite region was brought about by horizontal thrust ACKNOWLEDGMENTS pressures applied prior to and from a different direction The authors and their associates are greatly indebted than the forces that formed the present fold system. to many geologists, mining engineers, mining company In 1933, Willard determined that in the region be­ executives, and local residents without whose assistance, tween the Lehigh and Susquehanna Rivers the basal cooperation, knowledge, and records this report could beds of the Catskill Formation are younger towards the not have been adequately prepared, much less com­ west. This westward decrease in age was attributed to pleted. It is impossible to acknowledge the extert of intertonguing between continental red beds of the Cats- their help, and our hope is that none feel slighted that kill Formation and marine gray beds of laterally equiv­ their names are not mentioned here. alent but locally subjacent rock units. The & Reading Corp., through the late C. D. White (1934) and Willard (1936) independ­ William C. Muehlhof and John F. McCall, Chief Min­ ently theorized that an unconformity exists between the ing Engineers of the Reading Anthracite Co. aidei the Catskill and Pocono Formations in the vicinity of the investigation more than any other group or individual Southern Anthracite field. Neither, however, presented by making available for study the enormous volume of data supporting their theories. company data and by allowing company employee to During the years from 1931 to 1943, Willard, F. M. participate in many conferences with project personnel. Swartz, C. K. Swartz, and A. B. Cleaves described in William Williams and Harry Wiest are chief among varying detail the Ordovician to Devonian rock se­ those deserving special thanks for their patience and quence of the southern part of the Anthracite region. courtesy during these conferences. Willard (1934; 1935a-d; 1936; 1939a; 1941; 1943) con­ The late H. R. Randall, owner of the Wisconisco Coal centrated his work largely upon Middle and Upper Co., and his representatives, Thomas McCalon and John Devonian rocks and established much of the stratigra- Byerly, cooperated by making mining records of the phic nomenclature used in this report. C. K. and F. M. Lykens and Williamstown areas fully available and by Swartz studied the Silurian and Lower Devonian rocks conferring in the field and office. east and west of the report area (Swartz, C. K. and Harold E. Shompers, Pennsylvania State Min^ In­ F. M., 1931,1941; F. M. Swartz, 1939). Cleaves (1939) spector, aided the investigation greatly at its inception described the Oriskany Group west of the area and with by conducting field trips that showed the complexities Willard (Willard and Cleaves, 1939) substantiated the of coal bed correlations in the north halves of the Min- unconformity at the top of the Ordovician sequence. ersville and Tremont quadrangles and by pointing out During 1944 and 1945, two estimates of reserves of the geologic discontinuities that were later identified anthracite were published. The first of these was by the as folded faults. Pennsylvania Geological Survey (Pennsylvania Bur. The authors are particularly indebted to staff mem­ Statistics and Information, 1944) and the second, a cor­ bers of the Pennsylvania Geological Survey. Dr. Car- rection of the first, was by Ashley (1945). lyle Gray, former director of the State Survey, showed Commencing in 1950, a series of reports by members great interest and supported the investigation frna its of the U.S. Geological Survey on the Western Middle inception. Dr. A. A. Socolow, present director, has con­ and Southern Anthracite fields was published. This tinued this interest and support. Dr. D. M. Ho^kins, report is one of the series. Most of these reports describe R. R. Conlin, and L. A. Frakes, of the Pennsylvania the geology of parts of the Western Middle Anthracite Geological Survey, worked for several years in the area field (Rothrock and others, 1950; 1951a, b; 1953; Haley west of the project area and contributed many ideas and others, 1953,1954; Kehn and Wagner, 1955; Danil- and much information from their research. chik and others, 1955; Maxwell and Rothrock, 1955; PRINCIPAL GEOLOGIC FEATURES Wood and others, 1958; Danilchik and others, 1962; Arndt, Danilchik, and Wood, 1963; Arndt, Wood, and The rocks and unconsolidated sediments of the area Danilchik, 1963). Others describe stratigraphic corre­ range in age from Ordovician to Recent. Ordovician lations and structural phenomena that are characteris­ rocks consist of about 1,000 feet of shale and sandstone tic of the two coal fields (Wood and others, 1956; Arndt with a few beds of limestone. Rocks of Silurian age and others, 1959,1962; Arndt and Wood, 1960; Trexler range in thickness from 2,700± to about 4,500± feet 8 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA and are composed of a lower thin to thick sequence a progressive sequence. This sequence has b°en divided of gray conglomerate, sandstone, and shale overlain suc­ arbitrarily from northwest to southeast, on the basis of cessively by a thick sequence of red sandstone, siltstone, increasing complexity, into five structural stages. Initi­ and shale and a thin sequence of limestone. Lower ally, the horizontal strata of the region were flexed into Devonian rocks consist mostly of gray limestone, shale, broad, low folds (stage 1). The low folds w .re then suc­ and sandstone: Middle Devonian rocks are predomi­ cessively broken by low-angle thrust faults, built into nantly gray to dark-gray fine-grained elastics; Upper anticlinoria and synclinoria, and fractured by higher Devonian rocks are largely red sandstone, and shale. angle thrust faults (stage 2). The previously developed Devonian rocks range in thickness from 8,500± to thrust faults and folds of stage 2 were further folded 12,500± feet. Eocks of Mississippian age are composed and broken by additional high-angle faults (stage 3). of 1,000± to 3,800± feet of gray conglomerate and As deformation continued, the folds were overturned red sandstone, siltstone, and shale overlain by 3,000± and further fractured by tear faults and additional to 7,500± feet of red sandstone, siltstone and shale. The high-angle faults (stage 4). As the orogeny drew to a Pennsylvanian sequence, which locally contains a few close, recumbent folds and nappes formec1 south and beds of red sandstone, shale, and siltstone at its-base, east of the area (stage 5; Arndt and Wood, 1960). The consists largely of gray conglomerate, sandstone, silt- interrelations of structural features in the Anthracite stone, shale, and numerous beds of anthracite. It has a region show that any area containing folds and fault? maximum thickness of about 5,000± feet. Deposits of typical of the more complex stages and had previ­ unconsolidated Quaternary alluvium and talus mantle ously undegone deformation characteristic of the pre­ much of the area. These deposits locally are as thick as ceding stages. The folds and faults character stic of each as a few tens of feet on some hillsides and along some stage are preserved in discrete geographic parts of the valley bottoms. region. In a general way, structural features typical of The average thickness of the outcropping rocks is stage 3 occupy the report area north of tte trough of about 24,500 feet. This great thickness of rocks has been the Minersville synclinorium, and those typical of divided into 31 formations and members. In addition, stage 4 occur between the trough and Blue Mountain. within the thicker formations and members, many South of Blue Mountain, recumbent folds and nappes lithologic units have been mapped to aid in tracing of stage 5 prevail. structural features and in understanding and correlat­ ing the sedimentary f acies of the thicker units. STRATIGRAPHY The geologic structure is complex, the intensity of ORDOVICIAN SYSTEM deformation increasing from northwest to southeast. MABTINSBUBG SHALE Folding, faulting, and erosion related to the Taconic disturbance occurred southeast of the area in Late The Martinsburg Shale of Middle and Late Ordo­ Ordovician time and are presumed to have occurred vician age was named from Martinsburg, W. Va., by within the areas as well. Many east-northeast-trending Geiger and Keith (1891), who stated that the forma­ overturned and recumbent folds and nappes have been tion overlay the Shenandoah Limestone and underlay identified southeast and east of the area (Drake and the Massanutten Sandstone. Various authors (Rogers, others, 1960; Pennsylvania Geol. Survey, 1954). A late 1858b, p. 105; Lesley and others, 1895, p. 525-624; phase of the Acadian disturbance deformed the rocks Stose, 1909; Behre, 1927, p. 19-34, 1933, p. 138-148; along a similar trend in Early Mississipian time. Dur­ Stose, 1930, p. 634; Willard, 1943, p. 10P1; Pennsyl­ ing the Appalachian orogeny in post-Early Pennsylva­ vania Geol. Survey, 1954, p. 6') have used a wide variety nian pre-Late time, deformation again took of names and divisions for the Martinsturg. In this place along the east-northeast trend. The structural fea­ report the Martinsburg is considered to to those beds tures formed during the Taconic and Acadian disturb­ beneath the Tuscarora Sandstone. ances were deformed, obscured, and in some places The Martinsburg Shale underlies the southern slope virtually obliterated by structural features developed in of Blue Moutain in the Pine Grove and l^watara Hill the Appalachian orogeny. The earliest and latest struc­ quadrangles (GQ-689, 691) but is covered by talus of tural features of the Appalachian orogeny seem to have the overlying Tuscarora Sandstone whhh caps the resulted from compression from the east-southeast and mountain. It is poorly exposed in a few places a short east, but those formed during the medial part of the distance southwest of Round Head in the f watara Hill orogeny seem to have resulted from compression from quadrangle. the southeast rather than the east. The formation is the oldest stratigraphic unit ex­ The structural features of the Anthracite region that posed in the area; therefore, the nature of its basal con­ developed during the Appalachian orogeny formed in tact is not known. The upper contact is covered by talus, STRATIGRAPHY 9 but east of the area at Schuylkill Gap in Blue Moun­ most beds of the formation at Swatara Gap, 1 mile south tain, the Tuscarora is believed to rest on the Martins- of the report area, and Sterretts Gap, west of the Sus­ burg unconformably. West of the area, at Susquehanna quehanna River, with that of the Eden Group (of form­ Gap in the same mountain, Ordovician rocks younger er usage) of Ohio, Indiana, and northern Kentucty. than the Martinsburg underlie the Tuscarora and are According to this correlation, the fauna is of Lr.te, presumably conformable with the Martinsburg but not latest, Ordovician age (Twenhofel and others, (Willard and Cleaves 1938, p. 6-7). 1954, chart 2); any younger beds, if deposited at the The thickness of the Martinsburg Shale in the area gap and in the area, presumably were removed by is not known but probably greatly exceeds the 1,000 .feet erosion that resulted from the Taconic orogeny and pre­ believed to underlie Blue Mountain. Many geologists ceded deposition of the Tuscarora Sandstone. have computed thicknesses of the formation in the belt ORDOVICIAN-SILURIAN UNCONFORMITY of outcrop between the Delaware and Susquehanna Riv­ ers to the south of the area. However, the structure The Martinsburg Shale and the overlying Tuscarora of this belt is so complex that the thicknesses reported Sandstone of the report area generally are believed to be by different authors vary greatly even at the same lo­ separated by an unconformity that resulted from the cality. Reported thicknesses throughout the belt are Taconic orogeny. Evidence of the unconformity is lack­ highly variable and so erratic that no pattern of change ing in the area. Grabau (1921, p. 293), Miller (19?*>, in thickness can be established. p. 503-505), and Stose (1930, p. 646) concluded that The authors were unable to divide the Martinsburg an angular unconformity separates these formation? at into mejnbers. However, it is our opinion that only the Schuylkill Gap in Blue Mountain a short distance e^st lower black shale unit originally recognized by Stose of the area. Chance (in White, I. C., 1882, pi. 5), Lesley (1930, p. 634) is present, and that his upper sandstone (in Lesley and others, 1892-95, p. 674), Schuchert (1916, member was removed by pre-Tuscarora erosion. p. 549), Willard and Cleaves (1939, p. 1104), and Wil­ The Martinsburg consists mostly of gray to dark- lard (1943, fig. 6) believed that the angular contact gray shale interbedded with many beds of gray and between these formations at the gap is a fault. The yellowish-brown silstone and sandstone and a few beds authors, after examination of the exposures in the g^p, of gray to dark-gray limestone. The shale is tabular agree with Grabau, Miller, and Stose that the contact bedded in units a few inches to many feet thick and is an unconformity. We also believe that the uncon­ is commonly silty or sandy. The siltstone is also tabular formity extends at least as far southwest as Swatara bedded in units of similar thickness, is argillaceous, Gap. and generally contains fragments of gray shale. The SILURIAN SYSTEM sandstone is in beds 4 inches to 6 feet thick and is of The Silurian rocks that crop out in the report area two types: a tabular-bedded very fine grained to me­ are, in ascending order: the gray Lower Silurian Tis- dium-grained argillaceous sandstone commonly con­ carora Sandstone, the red and gray Middle Silurian taining pellets and fragments of gray shale, and a cross- Clinton Formation, the Upper Silurian Bloomsburg laminated to tabular-bedded medium- to coarse-grained Red Beds, and the gray Upper Silurian and Devonian sandstone. The limestone is dense, unfossiliferous, and Keyser Limestone. The gray, olive, and red Wills Cr^ek tabular bedded in units 6 inches to 3 feet thick. Shale and the gray Tonoloway Limestone of Late Silu­ The sediments of the Martinsburg Shale are marine rian age lie between the Bloomsburg Red. Beds r.nd and are believed by the authors to have accumulated Keyser Limestone a short distance west of the Kling- below the depth of intensive wave agitation. The even erstown quadrangle, but they are absent in the Pine bedding of the finer elastics and the limestone suggest Grove and Swatara Hill quadrangles. that the sediments composing these rocks were little Sediments that formed the Lower and Middle Silu­ affected by other types of strong currents during depo­ rian rocks were derived from a landmass east and south­ sition, but the fragments of gray shale in the siltstone east of the area which wa,s uplifted during the Taconic and sandstone units and the cross-laminations of the orogeny of Late Ordovician time. The landmass at f rst coarser elastics indicate the existence of currents of contributed a great volume of coarse detritus to a re­ moderate strength during their deposition. The cross- stricted shallow inland sea. By early Late Silurian time laminations dip northwest and suggest that the source the landmass had been eroded greatly, and the detritus, of the sediments lay to the southeast. which had become much finer, accumulated on a delta The Martinsburg Shale is generally considered to that gradually forced the inland sea northwestward. be of Middle and Late Ordovician age. E. O. Ulrich The uppermost Silurian rocks are carbonates and (in Stose, 1930, p. 643-644) and Willard and Cleaves that accumulated as the landmass was nearly base lev­ (1938, p. 6) correlated the fauna from the upper­ eled and perhaps submerged as the sea transgressed 10 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA southeastward onto the delta and open shallow-sea con­ Fresh exposures of. the sandstone and conglomerate ditions prevailed for the first time since deposition of of the Tuscarora are very light gray, medium gray, the Martinsburg Shale. yellowish gray, dark yellowish brown, lig-ht brownish gray, and brownish gray (Goddard, 1948). Joint sur­ TUSCAROBA SANDSTONE faces in freshly exposed rocks commonly are stained by limonite, which seems to disappear gradually as The Tuscarora Sandstone of Early Silurian age was weathering continues. Weathered rocks are predomi­ named by Darton (1896a, b) in his reports on the Pied­ nantly very light gray; but grayish-orange, yellowish- mont and Franklin quadrangles of , West gray, medium-gray, light-brown, and moderate-brown , and Virginia. The formation was originally colors are common. named the Levant White Sandstone by Kogers (1858b, Beds of the Tuscarora are i/2 inch to 6 feet thick and p. 105) and later the Medina White Sandstone by Les­ average about 1 foot in thickness. In the lower part of ley (in Lesley and others, 1892-95, p. 625). During the formation the average bed is about 3 fret thick, but succeeding decades the term "Medina" was used with in the upper part, the average thickness is much less. so many stratigraphic and chronologic meanings that Most beds are tabular or lenticular; however, wedge- the geologic nomenclature and correlations of Upper shaped and irregular beds are rather common. Ordovician and Lower Silurian rocks in , Cross-stratification is one of the principal character­ Pennsylvania, , and Virginia became con­ istics of the bedding of the Tuscarora. Punar cross- fused. As a result, local names such as Tuscarora were stratification of the "torrential" type is very common adopted. and simple cross-stratification is slightly l^ss common. The Tuscarora Sandstone underlies principally the Most planar cross-strata are small scale, being less than crest and southern slopes of Blue Mountain in the Pine 1 foot long (McKee and Weri, 1953). Simple cross- Grove and Swatara Hill quadrangles (GQ-689, 691), strata range in length from 1 foot to about 25 feet. Most but in a few localities, the upper part extends several cross-strata originally dipped northwest, which sug­ hundred feet down the north slope of the mountain. gests that the source of Tuscarora sediments lay south­ The rocks of the formation generally break into large east of the report area. Yeakel (1958) reached the same talus blocks which mantle both the Tuscarora outcrop conclusion as to the direction of the source in his study and underlying and overlying stratigraphic units. The of the formation in Pennsylvania and adjacent States. Tuscarora is poorly exposed. No complete or nearly The Tuscarora is composed largely of sandstone and complete sections have been found; therefore, the suc­ a subordinate amount of conglomerate, mostly in the cession of strata and their stratigraphic relations are lower part of the formation. Medium- to coarse-grained not known. sandstone is present throughout *the formation and is The Tuscarora Sandstone rests on the Martinsburg the principal constituent of the upper part. A few thin Shale unconformably. The upper contact is placed ar­ beds of siltstone, silty shale, and fine-grained sandstone bitrarily at the base of the lowest red bed typical of the are intercalated in the conglomerate and coarser grained Clinton Formation. It is rarely exposed in the area but sandstone. Compositionally, the sandstone is chiefly sub- is rather easy to trace in the field with the aid of aerial graywacke, but protoquartzite and orthoquartzite are photographs because of the erosional-lithologic con­ common. trast between red beds of the Clinton and gray beds of Pebbles in the conglomerate average about half an the Tuscarora. The contact seems to be consistently at inch in diameter but are locally as much $s 3 inches in the same stratigraphic horizon and probably is diameter. They are composed largely of light- to med­ conformable. ium-gray, milky, and white vein quartz and light- to Computed thicknesses of the Tuscarora Sandstone dark-gray, brownish-gray, and medium bluish-gray along Blue Mountain in the Pine Grove and Swatara ; small amounts of dark-gray and moderate- Hill quadrangles average about 400 feet. Available data red chert; and a few irregularly shaped fragments of indicate that the formation averages about the same gray to light-gray shale and . The clasts of vein quartz, quartzite, and chert are mainly subrounded to thickness wherever recognized as a separate strati- rounded, those of shale and slate are principally sub- graphic unit in eastern Pennsylvania. This consistency angular and were probably derived from the underly­ suggests that the topographic and structural irregular­ ing Martinsburg Shale. In most conglomerate beds the ities of the Taconic disturbance were reduced to rela­ clasts are scattered unevenly or are concentrated in tive smoothness during the Ordovician and Silurian trains. The matrix of the conglomerate is f ne- to coarse­ erosion cycle before the wide and even deposition of the grained common quartz, vein quartz, quartzite, and Tuscarora. chert and irregular fragments of mica and clay. STRATIGRAPHY 11

The orthoquartzite and protoquartzite are composed The siltstone and shale of the Tuscarora contain a mainly of grains of vein and common quartz and high percentage of identifiable silt grains in addition to quartzite and of lesser amounts of chert, tourmaline, unidentified clay minerals. The silt grains are chiefly and zircon. Interstitial material consists of biotite, angular to subangular common quartz and smaller muscovite, sericite, and unidentified clay minerals. The amounts of vein quartz, quartzite, chert, mica, and principal cementing material is silica. In a few thin rock fragments. sections, extensive quartz overgrowths are present on The environment in which Tuscarora sediments were grains of vein and common quartz. The average diame­ laid down has been discussed for years, and the con­ ter of grains is about 0.4 mm (medium), but the range clusions range from entirely marine deposition to in diameter is from 0.02 mm (silt) to 1.5 mm (very entirely nonmarine deposition (F. M. Swartz, 1948; coarse). Some orthoquartzite and protoquartzite have Folk, 1960, p. 21; Yeakel, 1958,1962, p. 1536). The fos­ a vague bimodal tendency; the lesser mode averages sils and sedimentary features of the rocks of the Trsca- 0.25 mm in diameter and the greater averages about rora are suggestive of accumulation in an environment 0.5 mm. that extended from the edge of a coastal plain fo** an The sorting of most orthoquartzite is excellent and unknown distance into shallow marine waters. The fol­ that of protoquartzite is moderate to excellent. Grains lowing evidence supports such accumulation. Arthro- in both types of sandstone are subangular to round but phycus imprints, which are commonly believed to are chiefly subround. indicate deposition in a strandline environment (Pelle- Quartzite grains tend to be slightly more angular tier, 1958, p. 1057), are numerous in the upper part of than grains of vein and common quartz, chert, tourma­ the formation. Stream-channel deposits are absert in line, and zircon. Some almost perfectly rounded grains the Tuscarora. Clay- and silt-sized particles are rela­ of vein and common quartz were broken during trans­ tively sparse in rocks of the formation, which suggests portation from the source area. These almost perfectly that they were largely winnowed out and that sediment rounded grains probably were derived from sedi­ sorting was probably accomplished by currents ether mentary rocks in the source area, whereas the quartzite than streams. The predominance of northwest-dipping grains probably were derived from metamorphic rocks. cross-strata suggests that deposition was from currents The mineral assemblage of the subgray wacke consists that moved consistently from the southeast, probably of grains of vein and common quartz; blebs and plates normal to the trend of a strandline. of sericite, biotite, chlorite, muscovite, and unidentified Arthrophycus alleghaniensis, a worm burrow or ani­ clay minerals; films of limonite and hematite; a few mal track, is the only fossil found in the Tuscarora of grains of leucoxene, rutile, tourmaline, and zircon; and the area. Clarke and Kuedemann (1912, p. 419) repeated varying amounts of fragments of quartizite, chert, that Dr. Gilbert Van Ingen found mvria, phyllite, shale and slate. Silica is the principal cement, cf. D. ostius, shawangi".nk, but some subgraywacke is cemented by hematite, limo­ globiceps, Stylonurus cf. S. myops, Eret- nite, and clay. topterus sp., and Arthrophycus alleghaniesis in float The diameters of the mineral grains in the subgray­ from the Tuscarora Sandstone at Swatera Gap. C. K. wacke range from 0.01 mm (silt) to 2.0 mm (very Swartz and F. M. Swartz (1930; 1931, p. 655) believe coarse). Many vein quartz grains and quartzite frag­ that this fauna firmly fixes the age as Early Silurian. ments reach diameters of 2.0 mm, but the average diame­ The Tuscarora Sandstone is generally considered to ter is 0.5 to 0.75 mm (coarse). Common quartz grains be the correlative of the Clinch Sandstone of the south­ have an average diameter of 0.25 to 0.35 mm, which is ern Appalachians, the Albion Group of western New somewhat less than that of vein quartz and quartzite. York, and the lower part of the Shawangunk Con­ Most grains of tourmaline and zircon are less than 0.25 glomerate of eastern New York, easternmost Pennsyl­ mm in diameter. In much of the subgraywacke, quartz­ vania, and . ite, and quartz grains interpenetrate because of pressure solution. In addition, about 50 percent of the vein quartz CLINTON FORMATION grains have semicomposite extinction and comb The Clinton Formation of Middle Silurian age was structure. named for Clinton, N.Y., by Conrad (1842, p. 228-235). Sorting in the subgraywacke is poor to very good. In terms of modern stratigraphic nomenclature, the Grains are poorly to well rounded but average sub- formation as originally defined included the rocks angular. Most quartzite fragments are less rounded lying between the Albion Sandstone, as it was then than are grains of vein and common quartz and chert, called, and the . Shortly after the turn whereas zircon and tourmaline grains are commonly of the century, Ulrich (1911, pi. 28) and Kindle and more rounded. Taylor (1913, p. 6-7) redefined the Clinton to include 316-352 O 69- 12 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA the Rochester Shale as the upper member. Many years The Clinton is composed almost entirely of interca­ before this redefinition, I. C. White (1883, p. 104-114) lated sandstone, silty shale, and shale. A fev^ thin beds had correlated the Clinton southward into eastern of conglomeratic sandstone are present in the 'lower Pennsylvania. Unfortunately, the stratigraphic units part of the formation near the crest of Blue Mountain that bound the formation in Newr York by either defini­ in the Swatara Hill quadrangle (GQ-689). tion are not recognized in eastern Pennsylvania. On the Rocks of the Clinton are predominantly grayish basis of regional correlations, therefore, the Clinton in red, moderate red, and pale red; some are pale brown, the area is considered to include the rocks between the light to medium dark gray, and light brovnish gray. Tuscarora Sandstone and the overlying Bloomsburg They commonly weather to the same colors and to Red Beds of Late Silurian age. grayish orange, light olive gray, and yellowish gray. The Clinton Formation underlies the northern slope The sandstone beds in the Clinton Formation are and, in a few places the crest of Blue Mountain in the commonly thicker than associated beds of silty shale Pine Grove and Swatara Hill quadrangles (GQ-689, and shale. Individual sandstone beds, which are gen­ 691). Outcrops are sparse and generally small. The erally about 1 foot 6 inches thick, range in thickness rocks of the formation, as does the Tuscarora Sandstone, from 1/2 mcn to 4 feet. Shale beds locally are as much weather into large talus blocks that mantle the south­ as 2 feet thick, but are chiefly about 1 inch thick. Most ern part of the outcrop belt of the overlying Blooms- strata are tabular; however, a few are lenticular and burg Red Beds. irregular. Small-scale planar and simple cross-stratifi­ The contact betwTeen the Clinton and the underlying cation is present in some outcrops, but is urcommon. Tuscarora Sandstone is placed arbitrarily at the base The sandstone of the Clinton is subgraywacke, pro- of the lowest red bed of typical Clinton lithology. toquartzite, and orthoquartzite in decreasing order of Although exposed at only a few places, it is easy to abundance. The subgraywacke consists of grains of trace because of a slight swale that has been eroded common and vein quartz; fragments of quartzite, in the basal beds of the Clinton and a small linear hill schist, slate, shale, and sandstone; grains and plates that has formed in the uppermost resistant sandstone of biotite, chlorite, muscovite, sericite, and leucoxene; beds of the Tuscarora. The contact between the red and grains of magnetite, ilmenite, rutile, tourmaline, zir­ gray beds of the Clinton and the much less resistant con; and films of hematite and limonite and unidenti­ overlying Bloomsburg Red Beds is not exposed in fied clay minerals. Several of the subgraywacke se­ the report area. The contact is believed to underlie a quences are highly ferruginous and contain as much as sharp topographic break in slope that resulted because 15 to 20 percent by volume of hematite as cement and of the marked difference in erosional resistance be­ interstitial material. These sequences were named in­ tween beds of the Clinton and beds of the Bloomsburg. formally the Center and Swatara iron by The break in slope is not well expressed on the topog­ C. K. Swartz and F. M. Swartz (1931, p. 638). Cement­ raphy of quadrangle maps GQ-689 and 691, but is ing media of the subgraywacke are chiefly silica and easy to trace on the ground in the field with aerial hematite, but in some beds are sericite, other micas, photographs. The contact between these formations as a binder matrix of quartz flour, and unidentified clay shown on maps GQ-689 and 691 is also the boundary minerals. The grain size ranges from very fine to between the Clinton and overlying Quaternary talus coarse, the average being fine. Sorting is poor to ex­ deposits. cellent but is mainly moderate to good. Grains are The thickness of the Clinton Formation in the re­ chiefly subround; however, subangular to round grains port area and nearby localities cannot be determined are rather common. Many quartz grains that lie in con­ because of thrust faulting. The maximum undupli- tact interpenetrate as the result of pressure solution; cated thickness on Blue Mountain is about 2,300 feet; whereas others do not interpenetrate because they are surrounded by a matrix of mica fragments and clay therefore, the formation is more than 2,300 feet thick which seems to have prevented pressure solution. at this locality, but how much thicker is unknown. The principal mineral constituents of the proto- The thickness of 2,300 + feet is the maximum reported quartzite are grains of common and vein quartz. Ac­ for the Clinton in eastern Pennsylvania. It seems likely cessory constituents are fragments of quartzite, schist, that the formation thins gradually to the northwest slate, shale, and sandstone and grains of biotite, mus­ and west away from this maximum in the report area covite, sericite, chlorite, rutile, tourmaline, zircon, to the approximate 1,000-foot average thickness re­ magnetite, ilmenite, and leucoxene. Some sandstone of ported at other localities in eastern Pennsylvania this type contains as much as 10 percent by volume of (Swartz and Swartz, 1931, p. 630, 640; Burtner and hematite, which occurs chiefly as cement and inter­ others, 1958; Miller, 1961, pi. 2). stitial material. Cementing media are silica and hema- STRATIGRAPHY 13 tite and, in a few places, sericite, other micas, and un­ water converted these two minerals into hematite. The identified clay minerals. Although the diameter of absence of glauconite and the small amount of chlorite grains ranges from 0.1 to 0.8 mm, the average diameter in the fine clastic rocks of the Clinton suggests that is about 0.2 mm (fine). Sorting is moderate to ex­ Folk's postulate is not applicable in the report area. cellent. The degree of original rounding of grains is Fossils have not been found in the Clinton Formation difficult to determine in most protoquartzite because of in the report area. A short distance to the south, how­ interpenetration due to pressure solution. Despite in- ever, at Swatara Gap, C. K. Swartz and F. M. Swartz terpenetration, the range of rounding seems to have (1931, p. 636-637) collected a large fauna. After study­ been from subangular to well rounded and to have ing this collection and additional collections from other averaged subround. localities in central and eastern Pennsylvania, they in­ The orthoquartzite of the Clinton is composed of a dicated on chart 3 of the "Correlation of the Silurian greater percentage of common and vein qiiartz grains Formations of " (Swartz, C. K., and than is the protoquartizite, but otherwise these two others, 1942) that the formation is correlative with the types of sandstone are similar. Niagara Series and is of Middle Silurian age. The U.S. The silty shales of the Clinton are predominantly Geological Survey considers the Clinton to be Middle quartzose and, to a much lesser extent, micaceous. They Silurian. are composed largely of silt-sized grains of common BLOOMSBURG BED BEDS and vein quartz embedded in a matrix of unidentified clay minerals. The clay shales are also quartz rich, but The Bloomsburg Red Shale was named by I. C. White (1883, p. 106) for the red rocks exposed along the east contain a much greater percentage of unidentified clay bank of Fishing Creek at the northern boundary lin*, of minerals than do the silty shales. Some beds of both types of shale contain a high percentage of hematite Bloomsburg, Pa. Subsequent geologists have abandoned the term "shale" and substituted "red beds" because the in the matrix. formation contains a considerable amount of red sr-nd- Clinton sediments probably accumulated in a near- shore marine environment where oxidizing and reducing stone. conditions predominated at different times. The marine The Bloomsburg Red Beds are poorly exposed in the environment is proven by fossils in the Clinton at Swat- area. Outcrops are in two gently rolling, subdued linear ara Gap and in correlative beds in the Shawangunk belts in the Pine Grove and Swatara Hill quadrangles Conglomerate of easternmost Pennsylvania (Swartz (GQ-689, 691). The southern belt underlies a series of and Swartz, 1931, p. 636-637, 655). The red color of valleys between Blue and Swope Mountains; the north­ many of the shale, silt-stone, and fine-grained sandstone ern belt occupies the core of the Roedersville anticline beds of the formation is due to hematite cement and in the central part of the Swatara Hill quadrangle. interstitial material. The hematite probably records The contact between the Bloomsburg Red Beds and oxidizing conditions that predominated during and fol­ the underlying Clinton Formation is not exposed in lowing deposition of these fine elastics. The medium- the area. It is placed arbitrarily at a sharp topographic and coarse-grained sandstone beds of the formation are break in slope at the lithologic change between resistant commonly gray and contain considerably less hema­ beds of the Clinton and less resistant beds of the tite. The gray color of these beds probably records re­ Bloomsburg (see description of the Clinton Formation). ducing conditions during and after deposition. A sec­ In the Pine Grove and Swatara Hill quadrangles, ond, but less likely, possibility is that the marine cur­ the contact between the Bloomsburg and the overlying rents that carried the finer elastics and iron either in Ridgeley Sandstone is unconformable. In its few ex­ solution or as hematitic material were localized by topo­ posures the contact is sharp; red beds of the Blooms­ graphic features on the sea bottom or were forced to burg apparently parallel gray conglomerate beds of the bypass localities where the coarser sediments were ac­ Ridgeley. North and west of the report area, several cumulating. A third, and much less likely, possibility hundred feet of uppermost Silurian and lowermost De­ is that the iron was deposited only from the marine vonian rocks intervene between these formations. The currents either before or after deposition of the coarse unconformity at the base of the Ridgeley must truncate sediments. Folk (1960, p. 42), in support of the latter these intervening rocks between the area to the north theory, postulated that correlative red Clinton fine elas­ and west and the exposures in the Pine Grove and tics in West Virginia were deposited a short distance Swatara Hill quadrangles, but data are scanty to ascer­ offshore from the mouths of streams that carried large tain where the unconformity truncates these inter'Ten- amounts of iron in solution. He postulated that the iron ing rocks. was precipitated as chlorite and glauconite along with The Bloomsburg Red Beds range in thickness from the fine elastics and that at a later time oxygenated about 700 feet in the northwestern part of the area to 14 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA about 1,800 feet in the southwestern part. Figure 3 The beds of the Bloomsburg range in thickness from shows the thickness of the formation in the area and the about y2 inch to about 2 feet 6 inches, the average being surrounding region. It was prepared from thicknesses about 1 foot. Most are tabular but some ar^ lenticular. measured by the authors, C. K. Swartz and F. M. Swartz Small-scale planar and simple cross-stratification is (1931), Miller (1961), Hoskins (1961), and I. C. White present in some medium- to coarse-grained sandstone. (1883). The formation thickens southeastward across The Bloomsburg is composed principally of siltstone the report area at a rate of about 35 feet per mile. This and very fine grained sandstone intercalatec1 with shale. average rate of thickening was calculated without ref­ Fine- to coarse-grained sandstone is rare, and granular erence to the structural foreshortening between locali­ to small pebble conglomerate is very rare. The sand­ ties where measurements were made. Tectonic analysis stone consists, in decreasing order of abundance, of very based upon all available structural and stratigraphic fine-grained to fine-grained protoquartzite,, very fine­ data indicates that the Silurian and Devonian rocks of grained to fine-grained orthoquartzite, and fine- to the area were shortened about 30 percent by folding medium-grained subgraywacke. and faulting; therefore, before the shortening, the Except for a difference in the amount of quartz, the Bloomsburg seems to have thickened southeastward at mineral constituents of the protoquartzite and ortho­ about 25 feet per mile. quartzite are similar. Both are composed largely of Where freshly exposed, the shale, siltstone, and finer common and vein quartz grains; scattered grains of grained sandstone of the Bloomsburg are predomi­ quartzite, chert, shale, mica, tourmaline, rutile, zircon, nantly grayish red, some being pale to moderate red, ilmenite, magnetite, and leucoxene; sparse grains of moderate reddish brown, or yellowish gray. The coarser andesine; and hematite and limonite. In either rock grained sandstone is generally greenish gray, but light type many grains are embedded in a matrix of hematite olive gray, dark greenish brown, and dusky brown are and limonite, which in some protoquartzite constitutes not uncommon. Weathered rocks are mainly pale red­ as much as 10- to 15-percent of the rock. The andesine dish brown to moderate reddish brown. Other weath­ grains are the oldest Observed occurrence of this min­ ered rocks are grayish red, dusky red, light brown, dark eral in rocks of the area. reddish brown, grayish brown, and moderate yellowish The cement of the protoquartzite and orMioquartzite brown. of the Bloomsburg is principally hematite and second-

404-499* ^ MONTOUR \ ( EXPLA NATION COUNTY!**

Area where Bloomsburg Red Beds have been removed by erosion and thickness control is not available -500- -750- Iscnachs Interval 250 feet 468 X Measured t> ickness, in feet

FIGURE 3. Isopach map of the Bloomsburg Red Beds, east-central Pennsylvania. STRATIGRAPHY 15 arily silica. Sorting ranges from very good to excellent. cally can be made is that the formation is younger than Two distinct grain-size modes are common in both types the Clinton Formation of Middle Silurian age and is of sandstone. The grains of the larger mode are sparse, older than the Bldgeley Sandstone of middle Early constituting not more than 5 percent of the rock. They Devonian age. A short distance west of the area, HosHns are usually well rounded, in contrast to those of the and Conlin (1958, p. 161) found in the Bloomsburg smaller mode which are subangular to subround. The Late Silurian ostracode assemblages, which they cor­ diameters of grains in the larger mode range from related with similar forms in the McKenzie Forma­ 0.15 to 0.9 mm and those of the smaller from 0.07 to tion and Wills Creek Shale of central Pennsylvania. 0.125 mm. C. K. Swartz and F. M. Swartz (1931, p. 659) also de­ The subgraywacke in the Bloomsburg consists of termined that the Bloomsburg in the region surrounding grains of vein and common quartz; small amounts of the area is of Late Silurian age and that it is laterally biotite, muscovite, chlorite, sericite, tourmaline, zircon, equivalent to the McKenzie and Wills Creek, and per­ and unidentified clay minerals; also rock fragments of haps to the lower part of the Tonoloway Limestone. quartzite, chert, and shale. Some subgraywacke contains They additionally correlated the Bloomsburg with the as much as 10 percent interstitial hematite. The cement­ Longwood and High Falls Formations of New Je**sey ing media are silica, hematite, and clay minerals. Sort­ and eastern New York and with the Vernon Shale of the ing ranges from poor to good. The grain size ranges Salina Group of central New York. Ailing and Briggs from 0.01 mm (silt) to about 1.0 mm (coarse sand) and (1961, fig. 12) correlated the Bloomsburg with the basal averages about 0.25 mm (fine to medium sand). Many part of the Cayuga Series of , Ohio, and New quartz grains have overgrowths, and others have deeply York and also considered it to be an equivalent of the sutured margins because of pressure solution. The orig­ Vernon Shale. inal rounding of grains is difficult to determine because WILLS CREEK SHALE of the sutured margins and overgrowths, but seems to have averaged about subround. The Wills Creek Shale was named by Uhler (1905, The siltstone in the Bloomsburg is similar in composi­ p. 20-25) for Wills Creek at Cumberland, Md. In 1911, tion to the protoquartzite and orthoquartzite. Two dis­ Ulrich (p. 522, 541, and pi. 28) correlated the forma­ tinct grain-size modes are present in much of the silt- tion into central Pennsylvania and stated that it under­ stone. The larger mode averages about 0.3 mm in diam­ lay the Tonoloway Limestone and overlay the Blooms­ eter, and the smaller is silt size. burg Red Beds. The shale in the f ormation is quartz rich, commonly The Wills Creek is not exposed in the area but is silty, and locally micaceous. Clay-sized particles consist believed to underlie much of it north of the Sweet largely of quartz, mica, and illite. Arrow fault zone. It is absent south of the fault r.one. The rocks of the Bloomsburg probably accumulated Where exposed in the surrounding region, the forma­ on a great delta whose source lay to the southeast. Some, tion consists of medium- to olive-gray calcareous shale, however, may have been deposited in lagoons and shal­ argillaceous limestone, and siltstone; red to olive sand­ low marine waters adjacent to the delta. No evidence stone; and olive-gray to brownish-red shale, siltstone, points exclusively to any of these environments other and sandy limestone. than a general lithologic similarity between the rocks The thickness of the Wills Creek Shale is unkrown of the Bloomsburg and the rocks of the Oatskill and in the 'subsurface of the area. The nearest outcrops are Mauch Chunk Formations, both of which contain at Dalmatia, about 8 miles west of the area, where sev­ deltaic and subaerial deposits (Barrell, 1907, 1913-14). eral hundred feet, of the upper part of the formation Ailing and Briggs (1961, fig. 12) concluded that the are poorly exposed. Between Dalmatia and the Sweet Bloomsburg accumulated on a large delta whose main Arrow fault zone, the Wills Creek thins in a south­ body lay in eastern New York and eastern Pennsyl­ eastward direction to extinction. Synthesis of much re­ vania. gional geologic and stratigraphic data indicates that The marine depositional environment of parts of the the formation thins in this direction because it has been Bloomsburg has been recognized for many years in cen­ truncated by pre-Ridgeley erosion, which also truncates tral Pennsylvania where red beds assigned to it inter- all other pre-Ridgeley formations clown to and includ­ tongue with marine gray shales and of the ing the upper part of the Bloomsburg Red Beds. TThus, McKenzie Formation and the Wills Creek Shale (Wil- the Wills Creek Shale in the subsurface of the report lard, 1939b, p. 14; Swartz, F. M., 1946, p. 20; Hoskins area probably is absent near the Sweet Arrow fault and Conlin, 1958, p. 156-161; Hoskins, 1961, fig. 6). zone, but it may reach a thickness of 400 ± feet in the Fossils have not been found in the Bloomsburg Eed northwestern part on the Hooflander Mountain Beds of the area, and the only age assignment that lo­ anticline. 16 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA According to Ailing and Briggs (1961, p. 544 and eroded from Tonoloway time into early Ridgeley time. fig. 21), the Wills Creek Shale accumulated during Owing to the lack of exposures north of the Sweet Cayuga time in an open sea that was bounded on the Arrow fault zone, the thickness of the Tonoloway in east by the Bloomsburg delta and on the west by Niag­ the subsurface of the area is conjectural. F : gure 4 de­ ara reef banks. The fauna of the formation is of Late picts a series of measured sections which illustrate the Silurian age. The formation is correlative with the lithology and thickness of the formation at localities middle part of the Bloomsburg Red Beds of eastern near the area. Pennsylvania (Swartz and Swartz, 1931, fig. 2) and A map showing postulated thickness variations of with the upper part of the of New the Tonoloway in the subsurface of the ar?a is shown York, Ohio, and Michigan (Swartz, C. K., and others, in figure 5. It was constructed by using the measure­ 1942, chart 3). ments shown on figure 4 and many other measurements in a region much larger than that of fipire 5. The TONOLOWAY LIMESTONE assumption was made in constructing the map that the The Tonoloway Limestone of Late Silurian age was formation, thins evenly southward across the area to named by Ulrich (1911, p. 590) from Tonoloway Ridge zero at the Sweet Arrow" fault. Thus, north of the fault west of Rock Ford, W. Va. As presently defined, the the Tonoloway is believed to thicken northward from formation rests conformably on the Wills Creek Shale 0 at the fault to about 250 feet in the subsurface of the and underlies conformably the Keyser Limestone of northern part of the area. The average rate of thicken­ Late Silurian and Early Devonian age. ing in that direction is about 20 feet per mile. The The contact between the Tonoloway and the under­ Silurian rocks of the area were foreshortened about 30 lying Wills Creek Shale is arbitrarily placed at the percent by folding and faulting. Before the folding horizon where the amount of the limestone above ex­ and faulting, therefore, the rate of northward thicken­ ceeds that of the clastic material below. The contact ing was about 14 feet per mile. between the Tonoloway and the overlying Keyser Lime­ The limestone of the Tonoloway accumulated in a stone is placed where laminated limestone of the Tonolo­ sea that was bounded on the east by the Bloomsburg way is overlain by nodular limestone of the Keyser. delta (Ailing and Briggs, 1961, fig. 12) and on the The Tonoloway is not exposed in the area, but may south by a low landmaiss, the Aubum promontory. The underlie much of the area north of the Sweet Arrow sea in which the limestone was deposited seems to have fault zone. It is absent at outcrops south of the fault, been widespread, as shown by the large area underlain The nearest exposure to the area is a few hundred feet by the formation and its correlatives Maryland to west of the Klingerstown quadrangle on the axis of the New York, but in places it became so shalk w that mud Hooflander Mountain aiiticlinei. There and elsewhere cracks formed. in the Susquehanna Valley, the formation consists of The Tonoloway Limestone contains a sparse marine very thin bedded to thick-bedded medium-gray lami­ fauna of middle Late to latest Late Silurian age nated argillaceous limestone. Strata in the upper part (Reeside, 1917, p. 193; Swartz, C. K., and others, 1942, of the Tonoloway generally are thick bedded and are chart 3). It is correlative with the Bossardville Lime­ characterized by vertical calcareous mud-filled cracks, stone of eastern Pennsylvania, New Jersey, and south­ which commonly unite to form prisms. At most locali­ eastern New York and with the Bass Island ties, strata in the lower part are thin bedded and shaly. of Michigan and Ohio (Ailing and Briggs, 1961, p. The formation is absent south of the Sweet Arrow 518). fault zone because of truncation by pre-Ridgeley Sand­ SILURIAN AND DEVONIAN ROCKS stone erosion or because of a depositional thinning and pre-Ridgeley erosion. F. M. Swartz (1939, fig. 10) KEYSER LIMESTONE showed that the area south of the fault was part of The Keyser Limestone of Silurian and Devonian age a highland mass which he named the Auburn promon­ was named by Ulrich (1911, p. 563, 590-591, and pi. 28) tory. In 1941, he (Swartz and Swartz, 1941, p. 1187) for Keyser, W. Va. Ulrich considered the Keyser to be postulated that the Tonoloway thinned south and south­ the basal member of the Helderberg Formation. Many east toward the promontory because of depositional years later F. M. Swartz (1939, p. 49) proposed raising thinning and pre-Ridgeley erosion. The authors believe the Keyser to formation rank separate from the Helder­ that the formation, was truncated by erosion north of berg and tentatively assigned it to the Silurian. In 1942, the Sweet Arrow fault zone before thinning out deposi- two committees that studied the correlations of Silurian tionally. However, they recog-nize that the depositional and Devonian rocks in North America (Sv^artz, C. K., thinning indicates that the highland mass south of the and others, 1942; Cooper and others, 1942) followed fault (Auburn promontory) was being uplifted and Swartz's recommendation and raised the Keyser Lime- STRATIGRAPHY 17 stone to a formation. The committee on Silurian corre­ unit between the Tonoloway Limestone and the I fan- lations assigned the Keyser to the Silurian but indicated data Member of the Helderberg Formation. The that it could be Devonian. The Devonian committee map (fig. 6) was compiled from the measured sections considered it to be wholly Silurian. The U.S. Geological illustrated in figure 4 and from additional thickness Survey recognizes the Keyser as a formation and desig­ measured in the region surrounding figure 6. The Key­ nates its age as Late Silurian and Early Devonian. ser-Coeymans-New Scotland sequence is believed to The. upper part of the Keyser Limestone crops out thicken northward in the subsurface of the area from only in the western part of the Klingerstown quadrangle a featheredge near the Sweet Arrow fault zone to about where it is poorly exposed (GQ-700). The lower part 250 feet in the northern part at a rate of about 22 feet of the formation is well exposed in a series of quarries per mile. The Silurian and Devonian rocks were short­ that lie in the Pillow quadrangle a few hundred yards ened about 30 percent by folding and faulting during west of this locality. There, it is a thin- to thick-bedded the Acadian and Appalachian . Thus, before medium- to dark-gray fossiliferous nodular limestone deformation, the rate of northward thickening was with a few interbeds of laminated to medium-bedded about 15 feet per mile. light- to medium-gray yellowish-gray weathering shale. Much of the region south of the Sweet Arrow fault The limestone is finely to coarsely crystalline and is zone is believed to have been a part of a Silurian and commonly transected by numerous thin calcite veins. Devonian landmass, the Auburn promontory. F. M. The upper part is less well exposed in the quarries and Swartz (1939, fig. 10 and p. 36, 39) postulated that the consists of a lower sequence of even-bedded light-gray to Keyser thinned depositionally southward towards the medium-bluish-gray shaly to thick-bedded limestone landmass. Regional evidence not only suggests south­ with a few interbeds of medium-gray nodular lime­ ward thinning, but also strongly suggests that the for­ stone, and an upper sequence of laminated light-gray to mation was truncated north of the fault zone before medium-bluish-gray finely crystalline limestone. deposition of the Ridgely Sandstone. West and northwest of the area, the Keyser seems The Keyser Limestone was deposited in a shallow to rest conformably upon the Tonoloway Limestone but widespread sea similar to that in which the under­ and to be overlain conformably by the Coeymans Lime­ lying Tonoloway Limestone accumulated. It is correla­ stone Member of the Helderberg Formation. However, tive with the Decker, Rondout, and Manlius Fo^ma- Reeside (1917, p. 199) has suggested that both contacts tions of southeastern New York, New Jersey, and east­ of the Keyser may be marked by faunal ern Pennsylvania and with the Cobleskill Limestone and lithologic breaks. The lower contact lies between and Decker, Rondout, and Manlius Formations of cen­ laminated limestone typical of the Tonoloway and nod­ tral New York (Swartz, C. K., and others, 1942, chart ular limestone characteristic of the Keyser. The upper 3). contact, which is more difficult to determine, is placed DEVONIAN SYSTEM above the laminated sparsely fossiliferous finely cry­ stalline limestones of the upper part of the Keyser and Devonian rocks form the thickest systemic sequence below the thick-bedded finely to coarsely crystalline cropping out in the area. They range in thickness from highly fossiliferous limestone typical of the Coeymans about 8,500 feet in the central part of the area to shout Limestone Member of the Helderberg. 12,500 feet in the Lykens quadrangle. The thickness of the Keyser Limestone in the sub­ Lower Devonian rocks consist of marine limestone, surface of the area and in most of the surrounding re­ sandstone, and shale. They are divided into the Helder­ gion is uncertain. Figure 4 shows measured sections of berg Formation and the overlying Oriskany Group The the formation on the Hooflander Mountain anticline Helderberg is divided, from the base up, into the Coey­ and at other localities adjacent to the area. It also mans Limestone Member, New Scotland Limestone shows that the formation is absent south of the Sweet Member and Mandata Member. The Oriskany Group is Arrow fault zone (fig. 4, sections 3-5). composed, in ascending order, of the Shriver Cher": and In the past, many geologists have not distinguished the Ridgeley Sandstone. the Keyser Limestone from the overlying Coeymans Middle Devonian rocks are composed of shale, silt- and New Scotland Limestone Members of the Helder­ berg Formation. As a result, precise regional data con­ stone, sandstone, and conglomeratic sandstone and r, thin cerning the thickness of the Keyser are sparse. In ad­ limestone sequence near the base. In ascending c^der, dition, the contact between the Keyser and these over­ they consist of the , the Selins^rove lying rocks commonly is difficult to determine without Limestone, and the Marcellus Shale and Mahantango faunal evidence. Therefore, the Keyser, Coeymans, and Formation of the . The Mahantango is New Scotland are considered as a single stratigraphic divided into a lower shale and sandstone member, the 18 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA 1 Dalmatia, Northumberlan County Hooflander Mountain, Northumberland

Schuylkill Haven, Schuylkill County Southeastern Swatara Gap, 1 mile east of part of Swatara Hill ebanon County Deturksville, quadrangle Schuylkill County Schuylkill Cou Needmore Shale

Bloomsburg Red Beds

Auburn promontory New Scotland and Coeymans Limestone Members 9 10 of Helderberg Formation

INDEX SHOWING LOCATION OF SECTIONS

SOURCES OF DATA Section 1. Compiled and modified from White (1883, p. 81), Reeside (1917, p. 216-220), Cleaves (1939, p 126). Section 6. Compiled and modified from Willard (1936, p. 595), Cleaves (1939, p. 128-129), Swartz and Swartz (1941, p. 1134-1135). Section 8. R. Fox well 1, Angas Corp One mile south of Snydertown, Northumberland County. Section 9. G. Krick well 1, Angas Corp. One mile north of Paxinos, Northumberland County. Section 10. Knarr well 1, Farmers Gas & Oil Co. at Numidia, Columbia County.

FIGURE 4. Columnar sections of Silurian and Devonian ro?ks from the Montebello Sandstone Member, and an upper shale HELDERBERG FORMATION member. The name Helderberg was first used in If 42 by Con­ Upper Devonian rocks are included in the Upper rad (p. 233) for the strata at the base of the Helderberg Devonian and Lower Mississippian Susquehanna Group Mountains in Albany County, N.Y. Conrad applied the which is divided into the Trimmers Rock Sandstone and the overlying Catskill Formation. In the southern name to the rocks that, in terms of modern stratigraphic part of the area the Catskill is divided, in ascending nomenclature, extend from the base of the Rochester order, into the Irish Valley, Damascus, Honesdale Sand­ Shale of the to the top of the Oriskany stone, and Spechty Kopf Members. In the western and Group. Over the years, the rocks assigned to the Helder­ northern parts of the area, the Honesdale Sandstone berg have been referred to by many names and have in­ Member thins out, and the indistinguishable Cherry cluded a great variety of strata which, in their widest Ridge and Damascus Members are mapped together as application, extended from the top of the Salina Forma­ the Buddys Run Member. tion of Late Silurian age to the base of thQ, Marcellus STRATIGRAPHY 19

10 Knarr well 1, Columb a County 8 9 EXPLANATION R. Fox well 1, G Krick well Northumberland Northumberla 1 1 2 nd / 1 1 County County ./ Hooflander Moun 1 1 tain,j A A_ A Metabentonite.. . . A A A Northumberla x/Meta- 1 County i i i 1 7 ^^- Rockville, -T-^- auphin Coun Needmore Shale .^0£^ Ridgeley Ridgeley(?) Sandstone Sandstone [~5 T^" -r , \ 7-^ ^__^_^ & o ^c & ^ \ \ \^^\ ^ >l d a Bloomsburg \ \ \\\ ^ Red Beds \ \\\ - - Mandata Member New Scotia ld '\ \^ ^^-^-^^^^ and Coeyrru \^\^ nestone Me Tnbers \\ \\ I | \ ^x -^~~~^^ of Helderbe ,g \ ^-M 1 ^^ i Formatio \\ ^ 1 Auburn \ | \\ promontory \

\______FEET 1 1

1 \A of Helderburg Forma- Keyser Limestone, entiated 1 1 \\ \ 1 200 | l\\\ 1 __ ^ \ \ 413 r^l i \ Covered interval

base of the Tonoloway Limestone to the top of the Selinsgrove Limestone.

Shale of Middle Devonian age (Wilmarth, 1938, p. mappable units and so must be called members here, 935-936; Eogers, 1858b, p. 107; White, I. C., 1883, p. rather than formations as they have been called in other 94-98; Swartz, C. K., 1913, p. 105-120; Eeeside, 1917, areas. p. 186-189; Swartz, F. M., 1939, p. 50-91). The Helderberg crops out at only one locality in the In the area of this report the Helderberg is of Early western part of the Klingerstown quadrangle (GQ- Devonian age and includes the strata lying between the 700). It is believed to underlie much of the area north of Keyser Limestone and the Shriver Chert of the Oris- the Sweet Arrow fault zone but is absent south of this kany Group. It consists, from the base up, of the Coey- zone. Members of the formation are not shown sepa­ mans and New Scotland Limestone Members and the rately on GQ-700 because they are too thin to depict recently recognized Mandata Member (deWitt and adequately at the scale of the map. Colton, 1964, p. 34-35). It has been mapped as a forma­ In the stratigraphic sections illustrated in figure. 4, tion because the Coeymans and New Scotland are not the Coeymans and New Scotland Limestone Members 20 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA

76"45' 76°

Measured thickness, m feet

SWATARA HILL

FIGUEE 5. Isopach map of the Tonoloway Limestone (shaded where absent). are combined because the Coeymans New Scotland con­ Scotland. The contact of the New Scotland with the tact at Hooflander Mountain (fig. 4, section 2) is uncer­ overlying Mandata Member is also covered and was tain. In fact, the two members can be separated only mapped where limestone and shale float are approxi­ at Dalmatia (fig. 4, section 1), 8 miles west of the area, mately equal in volume in the soil. where Reeside (1917, p. 217) recognized 2 feet of sandy The Mandata at Hooflander Mountain is about 25 limestone belonging to the Coeymans and 21.6 feet of feet thick (fig. 4, section 2). Its outcrop telt has been limestone belonging to the New Scotland. eroded into a slight swale, which is almost completely At Hooflander Mountain the Coeymans and New covered by soil containing numerous chips of ash-gray Scotland sequence consists, in descending order, of about or yellowish-gray calcareous chert and shale. The con­ 23 feet of dark-gray, medium bluish-gray to black, light- tact with the overlying Shriver Chert see^ns to be at gray weathering laminated to medium-bedded finely to about the place in the soil where the percentage of ash- coarsely crystalline slightly cherty fossiliferous lime­ gray or yellowish-gray chert and calcareous shale frag­ stone and 1 to 3 feet of dark-gray coarsely crystalline ments from the Mandata equals the percentage of larger, sandy limestone. very light gray and pinkish-gray fragments of vuggy The contact between the Heklerberg and the under­ chert from the Shriver. In wells north of the area (fig. 4, lying Keyser Limestone is covered in the area (GQ- sections 8-10), the Mandata is a dark-gray calcareous 700). It was mapped where the percentage of float from shale, 70 to 107 feet thick, separating the limestone and limestone typical of the Keyser equals the percentage of shale of the Shriver from the limestone of the New float from limestone typical of the Coeymans and New Scotland and Coeymans. STRATIGRAPHY 21

76°45

Measured thickness, in feet SWATARA HILL

FIGURE 6. Isopach map of the Keyser Limestone and Ooeymans and New Scotland Limestone Members of the Helderberg Formation (shaded where absent).

Figure T is an isopach map of the Mandata Member. an attendant clepositional thinning of the Helderterg The zero isopach line is a short distance north of the southward towards the promontory. Much regional Sweet Arrow fault, zone. The map was compiled from stratigraphic evidence strongly suggests that the rocks thicknesses shown on figure 4 and from other thicknesses of the formation were truncated a short distance north measured in the surrounding region. The Mandata may of the fault zone by pre-Ridgeley erosion. The thinning reach a maximum thickness of about 80 feet in the sub­ of the Helderberg and the increase in clastic detritus surface of the northern part of the area. It is believed indicate, however, that the promontory was being up­ to thicken northward at about 7 feet per mile. The lifted and eroded at the time the formation was accumu­ authors determined by structural analysis that the Silu­ lating. rian and Devonian rocks of the area were foreshortened The Coeymans and New Scotland Limestone Members about 30 percent during the Acadian and Appalachian of the Helderberg were deposited in an open sea that orogenies; thus, the pre-deformation rate of northward had a large fauna. The Mandata apparently accumu­ thickening was about 5 feet per mile. lated somewhat closer to shore where siliceous ooze The Helderberg Formation is absent south of the formed and much silt and clay was deposited. The detri­ Sweet Arrow fault zone, presumably because of trunca­ tus and silica probably were derived from high parts of tion by pre-Ridgeley erosion. The area south of the fault the Auburn promontory. The Mandata is less fossilif- zone is a small part of a Silurian and Devonian positive erous than the Coeymans and New Scotland. mass, the Auburn promontory. F. M. Swartz (1939, p. The Helderberg Formation contains a large Early 36, 39) noted a gradual increase in clastic detritus and Devonian fauna. The Coeymans and New Scotland 22 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA

76-45'

FIGURE 7. Isopaeh map of the Mandata Member of the Heidelberg Formation (shaded where absent).

Limestone Members are widely recognized from west- SHRIVER CHERT central Virginia to southeastern New York. The Man- The Lower Devonian Shriver Chert of the Oriskany data Member has been traced south westward into north­ Group was named by C. K. Swartz (1913, p. 91-92) for ern Virginia and Maryland and is correlated to the Shriver Ridge, Cumberland Mountain, Md. He (p. 121- north with the Port Ewen, Alsen, and Becraft Lime- 122) correlated it from the type locality northeastward stones of New York. into central Pennsylvania and recognized equivalent strata in New Jersey and New York. ORISKANY GROUP The formation crops out only on the flanks of the Hooflander Mountain, anticline near the w-^st border of The Oriskany Group of Early Devonian age was the Klingerstown quadrangle and is poorly exposed named by Vanuxem (1839, p. 273) for Oriskany Falls, (GQ-7QO). At this locality it is 30 to 60 feet thick and N.Y. Throughout a long and involved nomenclatural consists of thick-bedded dark-gray to black chert; thin- history, beds as old as the Port Ewen Limestone of the bedded medium- to dark-gray moderatelv crystalline and as young as the Esopns Shale fossiliferous cherty limestone; and dark-gray calcareous have been included by various authorities in the Oris­ cherty shale. Relatively pure chert is largely concen­ kany of New York (Wilmarth, 1938, p. 1561-1562). In trated in the upper part of the formation, whereas lime­ Pennsylvania the U.S. Geological Survey restricts the stone and shale are more common in the lower part. group to the Shriver Chert and Ridgeley Sandstone. Most of the chert in the upper part weathers very light STRATIGRAPHY 23 gray, but pinkish-gray and grayish-orange-pink frag­ An isopach map of the Shriver (fig. 8) was compiled ments are not uncommon. Most of the chert in the lower from thicknesses at the localities illustrated on figure 4 part weathers grayish yellow. and from thicknesses measured at other localities out­ The lower contact of the Shriver at Hooflander side the area of figure 8. The formation is absent sonth Mountain was described in the section on the Helder- of the Sweet Arrow fault zone, but may be as mucl as berg Formation. The upper contact with the overlying 60 feet thick in the subsurface of the northwestern part Ridgeley Sandstone is gmdational and is located where of the area. It seems to thicken northward at about 4!/o the rocks change from predominantly cherty limestone feet per mile. Before the Acadian and Appalachian orog­ to predominantly coarse sandstone and conglomeratic enies, which telescoped the rocks about 30 percent, the sandstone. formation probably thickened northwestward at about The sequence of beds of the Shriver is similar to that 31/.) feet per mile. at Hooflander Mountain throughout the region, except The Shriver is absent south of the Sweet Arrow fruit at Dalmatia (fig. 4, section 1), 8 miles west of the area, because it was truncated by pre-Ridgeley erosion. F'^ld where tongues of sandstone similar to the Ridgeley evidence from many localities in eastern Pennsylvania Sandstone are intercalated in the upper part of the for­ indicates that the Auburn promontory was tilted north­ mation. At all places the upper part of the Shriver is ward about the end of the deposition of the Shriver, highly fossiliferous, Avhereas the lower part is much less and the region was differentially eroded before the fossiliferous and locally barren. Cleaves (1939, p. 115) Ridgeley Sandstone was deposited. The region of thin observed this difference in fossil abundance throughout Shriver shown on figure 8 west of the report area seoms central Pennsylvania. to have been caused by a slowly rising linear positive

Isopachs Contour interval 10 feet X 20 Measured thickness, in feet SWATARA HILL

FIGURE 8. Isopach map of the Shriver Chert (shaded where absent). 24 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA element or arch (Harrisburg arch of Willard, 1941), RIDGELEY SANDSTONE which extended northward from the promontory and The upper unit of the Oriskany was named the Ridge­ which lay west of similar less pronounced arches during ley Sandstone Member by C. K. Swartz (1913, p. 90) Helderberg and Keyser times (figs. 6, 7). for a town in West Virginia. In 1939, Cleaves (p. 92- The upper part of the Shriver Chert seems to have 104) traced this unit from the Maryland-Pennsylvania been a near-shore deposit of siliceous ooze, silt, and clay border to Dalmatia in Northumberland County, 8 miles like the underlying Mandata Member of the Helderberg west of the area, and recommended classifying it as a Formation, except that the percentage of clay and silt formation in the Oriskany Group. The U.S. Geological was less and that of siliceous ooze, was significantly Survey has accepted Cleaves' designation. greater. The abundance of fossils, the general lack of The Ridgeley Sandstone crops out on the flanks of fine clastic detritus, and the local presence of clay-free the Hooflander Mountain anticline (GQ-700) in the tongues of sand may indicate that this part of the for­ northwestern part of the area and in two belts south of the Sweet Arrow fault zone (GQ-689, 691, 698) ; mation was deposited in waters somewhat clearer than it is poorly exposed at all places. On the r.nticline the those of the lower part and the Mandata. lower contact with the Shriver Chert is gradational, but The fauna of the Shriver Chert is of Early Devonian in the area south of the fault zone it is an ur conformity, age (Allan, 1935; F. M. Swartz, 1932; Cleaves, 1939). the sandstone resting on the Bloomsburg Bed Beds. In Cleaves (1939, p. 109) determined that 23 percent of the subsurface between the outcrops on the anticline and the Shriver fauna is present in the underlying Helder­ the fault zone, the Ridgeley, from north to south, pre­ berg Formation but that many common Shriver species sumably overlies successively the Shriver Cr^rt, Helder­ are not. present in the overlying Ridgeley and "vice berg Formation, Keyser Limestone, Tonoloway Lime­ versa" (p. 118). He also found that only 4 percent of stone, Wills Creek Shale, and a part of the Bloomsburg the combined Shriver-Ridgeley fauna is recognizable Red Beds. At Hooflander Mountain the upper contact in the overlying Needmore Shale and Selinsgrove Lime­ of the Ridgeley with the overlying Needmore Shale is stone and concluded that the Shriver-Ridgeley fauna a poorly defined disconformity (Cleaves, 1939, p. 108). was for the most part destroyed before the deposition South of the fault zone, the Needmore is absent, and of the Needmore and Selinsgrove. the Ridgeley is overlain unconformably by the Selins­ The Shriver underlies much of central Pennsylvania, grove Limestone. In the report area the Ridgeley ranges in thickness western Maryland, and eastern West Virginia. It is from 0 to slightly more than 50 feet (fig. 4). An isopach correlated with the lower part of the Oriskany Group, map (fig. 9) indicates that the formation probably is Formation, or Sandstone in Virginia, northeast Penn­ thickest in the subsurface of the report area. It also sylvania, and southeast New York. shows that the formation is absent locally north of the area. The thickness trends shown in figure 9 are oriented PRE-RIDGELEY UNCONFORMITY differently from the trends of the underlying Upper The Ridgeley Sandstone overlies the Shriver Chert Silurian and Lower Devonian formation^ shown in conformably on the Hooflander Mountain anticline figures 5 to 8. This difference in orientation of thickness (GQ-700), but south of the Sweet Arrow fault zone trends may reflect the earliest deformation paralleling (GQ-689, 691, 698) it rests on the Bloomsburg Red that of the later Acadian and Appalachian orogenies. Beds. Between the anticline and the fault zone a pre- Most weathered sandstone of the Ridgeley is grayish Ridgeley erosion surface cuts across intervening strata orange. Fresh sandstone ranges from light gray to light from the Shriver Chert to the Bloomsburg. Maps and olive gray, pinkish gray, medium gray, ard yellowish reports of the Second Pennsylvania Geological Survey gray. Most beds are thin bedded, tabular, and cross- (Sanders, 1881; White, I. C. 1883; Prime and others, bedded and have small-scale simple or planar cross- 1884; Smith, 1891) show that the Ridgeley rests on dif­ strata. ferent formations in different areas, but the existence of The Ridgeley is commonly a fine pebble protoquart- zite. The pebbles are largely vein quartz ar d quartzite, an unconformity was not postulated until 1939 (Cleaves, generally about half an inch in diameter; in a few places 1939, p. 106; Swartz, F. M., 1939, p. 87). More than they attain a maximum diameter of half an inch. The 400 feet of beds is truncated in a general southerly dir- grain size, except for the pebbles, ranges from very fine rection between the anticline and the fault zone. The to very coarse and averages medium. The grains range average rate of truncation of about 28 feet per mile in­ from angular to well rounded but average subangular. dicates a northward tilt of the report area of about a Cements are silica, limonite, hematite, and clay. At most quarter of a degree. localities the Ridgeley is a sparkling conglomeratic STRATIGRAPHY 25

76°45' 76" 15'

Isopachs Contour interval 10 feet X8 Measured thickness, in feet -"

FIGURE 9. Isopach map of the Ridgeley Sandstone (shaded where absent).

sandstone cemented by silica. South of the Sweet Arrow of the area. This latter possibility is supported by the fault zone, however, it contains some subgraywacke, occurrence in the Ridgeley of the clay mineral hallosite, and in the Hooflander Mountain area it has a few thin which is believed by some geologists to represent ex­ layers of intercalated chert. tremely weathered parts of shales (Rogers and Kerr, In addition to grains of vein quartz, the Ridgeley 1933, p. 287). The halloysite, however, may have been contains common quartz, biotite, chlorite, muscovite, deposited after being eroded and transported from land sericite, leucoxene, tourmaline, topaz, zircon, unidenti­ areas to the south. fied clay minerals, and fragments of chert, schist, phyl- The formation is recognized from east-central Penn­ lite, quartzite, and slate. Feldspar is sparse, but about sylvania to West Virginia. The fauna has been inten­ one-half percent andesine is present in some specimens. sively studied by many geologists, most of whom C. S. Ross (oral commun., 1960) identified small quan­ classify it as middle Early Devonian (Cleaves, 193?; tities of halloysite in thin sections from several localities. Allan, 1935; Swartz and Swartz, 1941). The Ridgeley The Ridgeley Sandstone accumulated in a sea that is correlative with the upper part of the Oriskany Sand­ advanced southward upon the pre-Ridgeley erosion sur­ stone of New York. It has been traced by the authors face. The Auburn promontory, most of which lay south into the Silurian (?) Inwood Sandstone of C. K. Swartz of the report area, probably was uplifted and eroded and F. M. Swartz (1931, p. 635-638), whose type locrl- in late- or post-Shriver time. However, uplifting may ity is at Swatara Gap, about 1 mile south of the central have been so early that the Lower Devonian rock se­ part of the area. The lack of pebbles in the Ridgelsy quence may not have been deposited in the southern part at this gap led C. K. Swartz and F. M. Swartz to con- 26 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA elude that the Bldgeley was absent and that its strati- upper contact of the member and the overlying Selins­ graphic position was occupied by an Upper Silurian grove is gradatioiial and is arbitrarily located where sandstone, which they named the In wood. the amount of limestone exceeds that of shale. The Needmore thickens from 0 feet near the Sweet POST-RIDGELEY UNCONFORMITY Arrow fault zone to 140 feet several mile? north of the An unconformity has been postulated at the top of report area (fig. 4). Tlie thickness in the area and the the Ridgeley Sandstone by Cleaves (1939, p. 108) and surrounding region is shown in figure 10. The Needmore Willard (1939a, p. 150)/They based their belief on seems to thicken northward at average rates of 10 feet (1) a thin limonite and hematite zone at the top of the per mile in the eastern part of the area r,nd 5 feet per Ridgeley, attributed to erosion or nondeposition; (2) mile in the western part. Deformation has shortened the regional variations in the thickness of the Ridgeley, Devonian rocks of the area about 30 percent. The rate presumably because of post-Ridgeley erosion; and (3) of northward thickening was about 7 fee4: and 3.5 feet, a f aunal break between the Ridgeley and the Needmore respectively, before deformation. Shale and Selinsgrove Limestone. The rocks of the Needmore apparently accumulated The existence of an unconformity is supported by on an erosional surface of low relief (fig. 9) that was the absence of the Needmore Shale, south of the Sweet cut in the Ridgeley Sandstone as the result of a minor Arrow fault zone. There, the Selinsgrove Limestone, rejuvenation of the Auburn promontory. The sea ad­ rests upon the Ridgeley. vanced from the north; shale accumulated first; then limestone and calcareous shale alternately were laid NEEDMORE SHALE down, and finally limestone predominati^d. The abun­ dant fauna of the formation suggests that the sea was Willard (1939a, p. 149) defined the Needmore Shale shallow and rather clear. as follows: Willard (1939a, p. 156-160) and Cleaves (1939, p. Beneath the Selinsgrove limestone and supplanting it south­ 109) considered the Needmore to be of Middle Devonian ward is a limy shale. * * * It is here dubbed the Needmore. age. The formation as recognized in the area probably * * * It is simply the downward continuation of the non-cherty correlates with the Schoharie Grit, the lower part of limestone, the Selinsgrove member, and is distinguished there­ from solely upon the greater proportion of argillaceous mate­ the Onondaga of New York (W. A. Oliver, Jr., oral rial, and "pari parsu", the decrease in limestone content. commun., 1967), and with the lower par* of the Need- In the northwestern part of the area and farther more Shale of Maryland (deWitt and Colton, 1964, p. north and west, the Needmore Shale rests unconform­ 40-42). Oliver considers the unit to be of Early and ably on the Ridgeley Sandstone and is overlain con­ Middle Devonian age. formably by the Selinsgrove Limestone. South of the SELINSGROVE LIMESTONE Sweet Arrow fault zone, the shale is absent, presumably because it was overlapped to the south by the limestone The Selinsgrove Limestone, herein adopted, was which there rests unconformably on the Ridgeley. named for Selinsgrove Junction, Pa. (YTillard, 1939a, The Needmore crops out only on the flanks of the p. 146). It rests conformably on the Needmore Shale Hooflander Mountain anticline in the western part of on the Hooflander Mountain anticline and north and the Klingerstown quadrangle (GQ-700). There it is west of the area. The contact is gradatioiial and is largely covered, and the continuity of the unit was placed arbitrarily at the horizon where limestone pre­ determined by tracing shale float mixed with sand­ dominates over shale. The Selinsgrove overlaps the stone and limestone from the Ridgeley and Selinsgrove. Needmore southward and rests unconformably on the The outcrop belt of the member generally underlies a Ridgeley Sandstone with a sharp contact south of the gently rolling valley bottom. Sweet Arrow fault zone. The lithology of the Needmore on the Hooflander The upper contact is too poorly exposed in the area Mountain anticline is virtually unknown. West of the to determine the relations, but farther north and west, area at Dalmatia, however, the Needmore is well ex­ the Selinsgrove grades upward into the Marcellus Shale. posed and is about 50 feet thick (White, I. C. 1833, p. The contact is placed where shale predominates over 81). There the upper 25 feet consists of alternating very limestone. thin and thin beds of medium- to dark-gray limestone The Selinsgrove Limestone is present in three belts and very thin beds of dark-gray calcareous shale. The of outcrop in the area: the flanks of the Hooflander lower 25 feet is largely dark-gray calcareous shale. The Mountain anticline (GQ-700); the southern part of the contact of the Needmore and the underlying Ridgeley Swatara Hill, Pine Grove, and Tower City quadran­ is a disconformity between sandstone and shale. The gles (GQ-689, 691, 698); and the central part of the STRATIGRAPHY

x50 Measured thickness, in feet

FIGURE 10. Isopach map of the Needmore Shale (shaded where absent).

Swatara Hill quadrangle near Sweet Arrow Lake ably resulted from a slight rejuvenation of the Harris- (GrQ-689). It commonly underlies a subdued rolling burg arch part of the Auburn promontory. or valley-bottom topography and is poorly exposed. The limestone of the Selinsgrove was deposited in a The formation, however, is well exposed about 8 miles southward-advancing sea that overlapped previously west of the area at Da.hnat.ia,. There, it consists of thin deposited Needmore rocks and lapped onto Ridgeley to thick beds of argillaceous fossiliferous finely crystal­ rocks south of the Sweet Arrow fault zone. The prolific line limestone intercalated with very thin to thin beds fauna of the limestone indicates that this sea was clear of fossiliferous silty calcareous shale. The fresh lime­ and shallow, and the lack of clastic detritus suggests stone is dark gray, medium bluish gray, grayish black, and brownish black, but it weathers light gray, dusty that the Auburn promontory was low. yellow, and grayish yellow. Fresh and weathered shale, The Selinsgrove is early Middle Devonian in age in contrast, is dark gray to black. Much of the weath­ (Willard, 1939a, p. 154-155; W. A. Oliver, Jr., oral ered limestone splits along closely spaced bedding commim., 1961). Willard (1939a, p. 154-155) considers laminae. The lithology of the unit in the poor exposures the fauna older than, but similar to, that of the Mar- of the area is consistent with that at Dalmatia. cellus Shale and Mahantango Formation. Cleaves The Selinsgrove is 0 to 105 feet thick in the area and (1939, p. 109) considers the fauna distinctly different surrounding region (fig. 4). Its thickness is shown by from that of the underlying Oriskany Group. The isopachs in figure 11. The unit thickens northward, Selinsgrove probably correlates with the upper part but is thin in a belt that trends north through the cen­ of the of New York and the upper tral part of the area. This depositional pattern prob- part of the Needmore Shale of western Maryland. 316-352 O 69 3 28 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA 76°45'

FIGURE 11. Isopach map of the Selinsgrove Limestone.

HAMILTON GROUP overlying stratigraphic unit which 'he nam^d the Ma~ The Hamilton Group of Middle Devonian age in­ hantango Formation. The authors here accep t Willard's definition of the Hamilton Group in Pennsylvania. cludes, in ascending order in the report area, the Mar- cellus Shale and the Mahantango Formation. The MARCELLUS SHALE latter is divided into a lower shale and sandstone mem­ ber, the Montetbello Sandstone Member, and an upper The Marcellus Shale of Middle Devonirn age was shale member. The group is underlain by the Selins­ named by Hall (1839, p. 295-296) for Marcellus, N.Y. grove Limestone and is overlain by the Trimmers Rock As originally defined, the formation included the rocks

Sandstone of Late Devonian agre.o between the overlying Ludlowville Shale anc1 the under­ Vanuxem (1840, p. 380) named the Hamilton for lying Seneca Member of the Onondaga Limestone. West Hamilton, N.Y. The group, as originally denned, Cooper (1930) and Goldring (1931, p. 190-192, 369) included only the rocks later assigned to the Ludlow- redefined the Marcellus of New York to include the ville Shale. In 1842, Vanuxem (p. 150-163) redefined rocks between the Skaneateles Shale and the underlying the Hamilton to embrace the strata between the over­ Onondaga Limestone and assigned it to the Hamilton lying Tully Limestone and the underlying Marcellus Group. In the area, the Marcellus rests on the Selins­ Shale. Clarke (1885) redefined the group in New York grove Limestone, correlative with the upper part of the to include the Marcellus, and Willard (1939a, p. 165- Onondaga, and is overlain by the lower shal0- and sand­ 200; 1939b, p. 9) proposed that in Pennsylvania the stone member of the Mahantango Formation. The latter Hamilton Group include the Marcellus Shale and an member contains beds that are probably correlative with STRATIGRAPHY 29 the Skaneateles Shale (Willard and Cleaves, 1933, p. promontory was relatively low during Marcellus time. 766-774). Fossils are rare, which suggests that the detritus fr->m The Marcellus crops out in three belts, where it is the promontory probably accumulated in rather mucMy poorly exposed. The northernmost belt underlies the waters. flanks of Hooflander Mountain anticline in the Kling- The sparse fauna of the Marcellus Shale is of Middle erstown quadrangle (GQ-700). The central belt crops Devonian age (Willard, 1939a, p. 161,172). The forma­ out on the Koedersville anticline in the central part of tion in the area is believed to be of the same age as the the Swatara Hill quadrangle (GQ-689), and the south­ type Marcellus of New York because the fauna is sim­ ernmost belt underlies the slopes of Swope Mountain ilar and the formation is overlain and underlain by and adjoining hills in the southern part of the Swatara rocks that contain similar fossil faunas. It is correlated Hill and Pine Grove quadrangles (GQ-689, 691). The with the of Ohio and the Dundee belts are generally eroded into a subdued rolling topog­ Limestone of southern Michigan (Cooper and others, raphy in valley bottoms or on adjacent hillsides. 1942, chart, 4). The stratigraphy of the Marcellus Shale is not well MAHANTANGO FORMATION known because of cover and structural complications; Willard (1935a, p. 202, 205-223) named the Mahan­ however, the upper part of the formation is well ex­ tango Formation for the North Branch of Mahantango posed a short distance downstream from the dam at Creek in Perry and Juniata Counties. He included the Sweet Arrow Lake (GQ-689). Wlierever exposed, the rocks between the top of the Marcellus Shale and the Marcellus is a grayish-black to black laminated to non- base of his Portage Formation. laminated nonfossiliferous to slightly fossiliferous The Mahantango is the upper formation of the silty to nonsilty sooty fissile shale. The shale commonly Hamilton Group in this area. It consists of a lower weathers to light-gray and medium-gray paper-thin shale and sandstone member, the Montebello Sand­ flakes. Septarian and calcareous concretions are abun­ stone Member, and an upper shale member. It incluies dant in some outcrops but are absent at most. the strata between the underlying Marcellus Shale r,nd The contact of the Marcellus Shale with the under­ the Trimmers Rock Sandstone and all strata that lying Selinsgrove Limestone is not exposed in the area, locally are assigned to the upper part of the Middle but in the surrounding region the change from lime­ Devonian Series. However, the Tully Limestone and the stone to shale is graclational over a few feet. It is arbi­ Burket Black Shale Member of the , which trarily placed at the horizon above which fissile nonlimy overlie the Mahantango at the type locality but are black sooty shale predominates over limestone and absent in the report area, are of Middle Devonian age. dark-gray limy shale.

The boundary between the Marcellus and the over­ LOWEE SHALE AND SANDSTONE MEMBER lying lower shale and sandstone member of the Mahan- tango is generally covered, but where exposed, is located The lower shale and sandstone member includes the where fissile black sooty shale predominates over very strata from the top of the Marcellus Shale to the base fine grained sandstone or dark-gray, browni-gray, and of the Montebello Sandstone Member. These strata have olive-gray shale and siltstone. Locally, the lower shale not previously been accorded member status in the and sandstone member of the Mahantango is absent in vicinity of the report area and have been assigned to the area south of the Sweet Arrow fault zone, and typi­ the Marcellus by some authors and to the Montebello cal Marcellus shale is overlain by the Montebello Sand­ by others (Lesley and others, 1892-95, p. 1217; Willard, stone Member. 1939a, p. 172-200; Miller, J. T., 1961, p. 27-30; Dyson, The Marcellus Shale is 50 to 700 feet thick in the area 1963, p. 17-19). and the surrounding region (fig. 12). The regional The lower member of the Mahantango Formation trends in thickness are shown by isopachs in figure 13. crops out on the Hooflander Mountain anticline (GQ- The formation is less than 100 feet thick over most of 700), on the Koedersville anticline (GQ-689), and on the southern part of the area and gradually thickens the south slope of Swope Mountain and adjacent hills northward and north-northeastward to about 700 feet (GQ-689, 691). In all three areas this member under­ in the northeastern part at an average rate of 35 to 50 lies slopes capped by the Montebello Sandstone Mem­ feet per mile. The Devonian rocks of the area were tele­ ber. It is largely covered by a heavy mantle of soil scoped about 30 percent during the Acadian and Appa­ and talus blocks, and as a result, the lithology is not ade­ lachian orogenies. The Marcellus Shale thickened quately known. northward in the northern part of the area before this The lower contact of the lower shale and sandstone deformation at an average rate of 25 to 35 feet per mile. member is at the top of the black sooty fissile shale The rocks of the Marcellus Shale were deposited in a characteristic of the Marcellus. The basal bed of the sea that overlapped upon the Auburn promontory far­ member at some places is a very fine grained sandstone ther south than any preceding Late Silurian and Devo­ and at others is a dark-gray, brown-gray, or olive-g^ay nian sea. The fine detritus in these rocks and the more shale or siltstone. The upper contact of the member is extensive overlap of the sea probably indicate that the at the horizon where fine- to coarse-grained sandstone R. Fox well 1. Southeastern o q Southeastern Near Dalmatia, Angas Corp., G. Krick well 1, part of Swatara Hill Rockville quarries, Near Dalmatia, 8 part of Swatara Hill Northumberland Selmsgrove Junction, Northumberland Angas Corp., quadrangle, Susquehanna River, Northumberland Hooflander Mountain, Swatara Gap, South of Sweet Arrow Lake, quadrangle. County Northumberland County County Columbia County Schuylkill County Dauphin County County Northumberland County Lebanon County Schuylkill County Schuylkill County Lower shale and sandstone member of Mahantango Formation Lower shale and sandstone member of Mahantango Formation .Olive-brown shale

TT95 TT 100 Bloomsburg Auburn promontory Red Beds

FEET 0 EXPLANATION

SOURCES OF DATA Section 1 Donald M. Hoskins and Richard R. Conlin (oral commu ., 1961). Section 2. Compiled and modified from White (1883, p. 79). Section 6. Compiled and modified from Willard and Cleaves

Calcareous shale

FIGURE 12. Columnar sections of the Marcellus Shale. STRATIGRAPHY

76°45

FIGURE 13. Isopach map of the Marcellus Shale. of the Montebello predominates over shale and siltstone. The member is well exposed in the spillway below The lower member is about TOO feet thick (fig. 14, sec­ the dam at Sweet Arrow Lake (GQ-689). There, it con­ tion 1) on the Hooflander Mountain anticline (GQ- sists, from the base upward of a 20 ± foot thin- to 700). The upper 150± feet is poorly exposed, but seems thick-bedded olive-gray to dark-gray very fine- to to consist of olive-brown, dark-olive-gray, dark- fine-grained sandstone overlain by a 95 ± foot unit of greenish-gray, and medium-dark-gray siltstone and dark-gray to brownish-gray laminated silty shale and shale. A few thin beds of very fine grained medium-gray sandstone (fig. 14, section 4). sandstone are present in the uppermost 50 feet of the About 50 feet of dark-gray to brownish-gray lami­ member. The lower 550± feet of the member is covered, nated shale of the lower shale and sandstone member but a short, distance west of the area, the rocks in this similar to the 95± foot unit south of Sweet Arrow Lake part of the member crop out and are composed of inter- is poorly exposed in the southeastern part of the Swa- bedded dark-greenish-gray to medium-dark-gray silt- tara Hill quadrangle, a short distance south of Movers stone and shale and medium- to dark-gray very fine to (GQ-689) (fig. 14, section 6). fine-grained sandstone. The lower shale and sandstone member in the report area ranges in thickness from 0 to about 700 ± feet Part of the lower shale and sandstone member is exposed about 1.4 miles south of Pine Grove, where it (fig. 14). It is absent in much of central Schuylkill consists, from the base upward of about 90 feet of inter­ County (fig. 15) along a northeast-trending arch that calated laminated to thin-bedded yellowish-gray to originated before deposition of the Montebello. The light-olive-gray very fine grained sandstone and silt- member thickens northwestward and southeastward stone and about 20 feet of dark-gray shale (fig. 14, away from the arch at an average rate of about 50 sections). feet per mile. Crustal shortening of Devonian rocks in 32 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA

I mile east of Southeastern Hooflander Mountain, Swatara Gap, South of Pine Grove, Sweet Arrow Lake, Deturksville, Swatara Hill quadrangle, Northumberland County Lebanon County Schuylkill County Schuylkill County Schuylkill County Schuylkill County

Trimmers Rock Sandstone_____

Upper shale member

Lower shale1 and sandstone; member/ TT 1706± EXPLANATION FEET 0

Conglomeratic sandstone Poorly exposed

TT 2170'-2190±

Fault INDEX SHOWING LOCATION OF SECTIONS

Shale

FIGURE 14. Columnar sections of the Mahantango Formation. the area averaged about 30 percent, and the average lard (1939a, p. 180-200) defined the Montebello 'as a rate of thickening before shortening probably was facies or sandstone member of the Mahr.ntango For­ about 35 feet per mile. mation. The authors here adopt the Montebello Sand­

MONTEBELLQ SANDSTONE MEMBER stone Member of the Mahantango Formation. The existence of the arenaceous strata assigned to the Claypole (1885, p. 67-68) recognized a resistant sand­ Montebello was not recognized by geologists who stone in the midst of the generally soft beds of the worked in central Pennsylvania before I. C. White Hamilton Group in Perry County and named it the (1883, p. 78-82) and Claypole (1885, p. 67-68). This Hamilton Montebello Sandstone for Montebello Nar­ oversight is difficult to understand because some of the rows on the Little . Subsequently, Wil- more prominent mountain ridges in that part of the STRATIGRAPHY 33 76° 15'

EXPLANATION -500- -1*00- Isopachs Contour interval 100 feet

X50 Measured thickness, in feet

BERKS CO SWATARA HILL

FIGURE 15. Isopach map of the lower shale and sandstone member of the Mahantango Formation (shaded where absent).

State are underlain by the member. (GQ-700). It consists, in ascending order, of 2CO± The Montebello crops out on Hooflander Mountain feet of fine- to medium-grained sandstone, 140 ± fee4" of and Fisher Ridge in the northwestern part of the area covered rock, presumably shale, and 150 ± feet of (GQ-700) and on Stone Ridge and Swope Mountain sandstone that locally contains vein quartz and quartz- and adjacent ridges in the southeastern part (GQ-689, ite pebbles as much as 1 inch in diameter in the upwr 691,698). 20 to 40 feet (fig. 14, section 1). The ridges underlain by this member generally are About 1 mile south of Pine Grove (fig. 14, section 3; rough and steep, and their slopes are commonly covered GQ-689, 691), the Montebello consists of about 500 by a heavy mantle of soil and talus. feet of fine- to coarse-grained sandstone. The upr>er The contact between the Montebello and the under­ 50 to 60 feet of the unit contain pebbles of vein quartz lying lower shale and sandstone member is placed and quartzite as much as 1 inch in diameter and abun­ where fine- to coarse-grained sandstone predominates. dant, but poorly preserved molds of . In Hooflander Mountain and Fisher Ridge a 50± foot About 250 feet of the lower part of the Montebello transition zone intervenes between distinct shale and crops out (fig. 14, section 4) near the dam at Sv^eet sandstone , but is absent in the spillway of Arrow Lake (GQ-689), where it consists largely of Sweet Arrow Lake and elsewhere in central Schuyl- fine- to coarse-grained sandstone and a few thin bed? of kill County. There, the basal fine- to coarse-grained siltstone. The upper part of the member is cut off by sandstone of the Montebello rests directly upon shale the Sweet Arrow fault. and siltstone of the lower member. The local absence About 1 mile east of Deturksville (fig. 14, section 5; of the lower shale and sandstone member of the Mahan­ GQ-689) the Montebello is about 350 feet thick, 'and tango Formation in central Schuylkill County and the near Moyers (fig. 14, section 6; GQ-689) it is about 400 general absence of the transition zone (fig. 15) in feet thick. At these localities the lower part of the mem­ this same general area suggest that this part of the ber consists of fine- to coarse-grained sandstone, the county was subjected to pre-Montebello erosion that medial part is covered, and the upper part consists of locally cut as deep as the upper part of the Marcellus conglomeratic sandstone containing pebbles as much Shale. as 1 inch in diameter and molds. The Montebello Sandstone Member is 470 to 490 The Montebello is well exposed a short distance scTith feet thick on Hooflander Mountain and Fisher Ridge of the area at Swatara Gap (fig. 14, section 2), where it 34 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA is 476 feet, thick and consists of fine- to medium-grained are dark greenish gray, olive black, and grayish brown. sandstone with a few interbeds of siltstone. The beds in the Montebello are chiefly tabular and The member is 290± to 710± feet thick in the area parallel laminated ; large-scale cross-stratificition is un­ (fig. 16) and is thickest in an area extending from south­ common. The thickness of individual units ranges from ern Schuylkill County northwestward into central west­ i/4 inch to 20 feet and averages about 1 foot. ern Schuylkill County (fig. 16). The thick area Most of the sandstone in the Montebello is medium bifurcates in central western Schuylkill County, one to coarse grained. Individual constituents range from subarea extending northwestward into Northumberland very fine grains to 2-inch pebbles. The larger clasts County and the other extending northeastward across consist almost entirely of vein quartz and qup.rtzite. The northern Schuylkill County. grains range from angular to well rounded and average Willard (1939a, fig. 46), in his description of the subangular. Many quartz grains interpenetrate. Others, Montebello, concluded that a landmass south of the mostly embedded in a clay and sericite matrix, do not area shed a large volume of coarse elastics during deposi­ interpenetrate and are rounded to well rounded. This tion of the member. He named this landmass "Cape difference in rounding and interpenetraticn suggests Cumberland/' It seems likely that the Cape Cumber­ that the matrix protected the embedded grains from land of Willard was a rejuvenated part of the Auburn pressure solution. promontory. The Montebello is composed mostly of subgray wacke The discordancy of regional thickness trends between and protoquartzite. The principal mineral constituents the Montebello and the lower shale and sandstone mem­ of both rock types are grains and fragments of vein ber (figs. 15, 16) suggests that the northeast-trending arch of late or post-lower shale and sandstone time sup­ and common quartz, sericite, quartzite, and unidentified plied little sediment during Montebello time. clay minerals. A few grains of halloysite, leucoxene, Fresh sandstone and siltstone in the Montebello are muscovite, ilmenite, magnetite, tourmaline, and uniden­ principally light olive gray and greenish gray, but tifiable plagioclase and fragments of schist and siltstone light- to medium-dark-gray, olive-gray, and yellowish- are present in most thin sections. Much of the plagioclase gray hues are not uncommon. Most weathered rocks are seems to be altered to sericite and clay and may be the medium- to medium-dark-gray; however, many are principal source of the unidentified clay minerals and brownish gray, yellowish gray, and olive gray; a few halloysite.

76°45' 76° 15' 40° | .= 45' KLINGERSTOWN

EXPLANATION

500 600 Isopachs Contour interval 100 feet

X 350

Measured thickness, in feet

.500 Compu^d thickness

BERKS CO SWATARA HILL

FIGURE 16. Isopach map of the Montebello Sandstone Member of the Mahantango Formation. STRATIGRAPHY 35

TIPPER SHALE MEMBER sandstone. In the vicinity of Fisher Kidge and Hooflander Mountain, however, it is at the base of a The upper shale member of the Mahantango Forma­ 50-foot transition zone that consists of shale and thin tion includes the rocks from the top of the Montebello sandstone beds. In the area south of the Sweet Arrow Sandstone Member to the base of the Trimmers Eock fault zone, an abrupt change from sandstone to shale Sandstone. These are the strata that Willard (1935a, p. marks the contact. 202, 205-223) had in mind when he named the Mahan­ The contact of the upper member and the overlying tango. From a regional viewpoint, he considered the Trimmers Kock Sandstone is conformable, and regional underlying Montebello Sandstone Member to be a local relations indicate that these units intertongue. It is well rock sequence of importance only in Perry, Juniata, and exposed at many places on the limbs of the Pine G~ove Dauphin Counties. syncline where it is at the change from shale, silty sTA ale, The member crops out in four belts in the area. The or siltstone to sandstone. northernmost of these belts fringes Fisher Eidge and Figure 14 shows five incomplete measured strati- Hooflander Mountain (GQ-700). The member crops graphic sections of the member. These sections and data out in two belts on the north and south limbs of the Pine from the maps (GQ-689, 691, 698, 699, TOO) indicate Grove syncline and in a fourth belt between the North that the member ranges in thickness from about 900 Sweet Arrow and Sweet Arrow faults (GQ-689, 691). feet in eastern Schuylkill County to 1,250± feet in The member underlies valleys between ridges that are Dauphin, Lebanon, and central Schuylkill Counties held up by the Montebello Sandstone Member and the (fig. 17) and that the member thins east, north, and west Trimmers Eock Sandstone. These valleys in the south­ ern part of the area are generally wide, flat bottomed, of Dauphin, Lebanon, and central Schuylkill Counties. and alluviated. In contrast, the valleys adjacent to The rocks of the upper shale member are medium to Hooflander Mountain and Fisher Kidge are steep sided dark gray, brownish gray, olive brown, and olive gray and partly filled with talus from the Montebello and and weather to buff hues. Most beds are 1 to 2 irches Trimmers Rock. thick, but some are as thin as one-eighth inch, and a The contact between the upper shale member and few are as thick as 2 feet. the underlying Montebello generally is gradational and The member is composed principally of non?ilty most commonly placed where shale predominates over shale, lesser amounts of silty shale, and small amounts

768 15'

EXPLANATION -1000- -900-

Isopachs Contour interval 100 feet

X 1000± Measured thickness, in feet

,1000 Jomputed thickness, in feet

FIGURE 17. Isopach map of the upper shale member of the Mahantango Formation. GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA 76°15'

TREMONT / ^MINERSVILLE

EXPLANATION

-1500- -,'600- Isopachs Contour interval IQOfeet

X1350± Measured thickness, in feet .1850 Computed thickness, in feet

FIGITBE 18. Isopach map of the Mahantango Formation.

of intercalated very fine grained sandstone. The chief this part of the area was uplifted late in the deposi­ mineral constituents of these rocks are grains of vein tion of the member and that erosion removed any pre­ and common quartz, unidentified clay minerals, and viously deposited sediments of the member and a part sericitic material. of the Marcellus Shale. This uplift marked the begin­ ning of a rejuvenation of the Auburn promontory, as THICKNESS OF THE MAHANTANGO FORMATION recorded by the coarse elastics of the Montebello The Mahantango Formation is 1,200 to 2,190 feet Sandstone Member. thick in the area (fig. 18) as shown by sections measured The transitional sequence of shale and sandstone at at the localities in figure 14 and from other measure­ Hooflander Mountain and Fisher Eidge indicates that ments in the surrounding region. Eelatively thick the Montebello accumulated upon the kmer member Mahantango flanked by thinner areas extends south­ without sedimentary interruption. In central Schuylkill eastward from the vicinity of Hooflander Mountain and County, however, the Montebello was laid down on a Fisher Eidge into Berks County. erosion surface that had been cut through the lower member into the Marcellus Shale. Deposition of Monte­ DEPOSITIONAL ENVIRONMENT, AGE, AND CORRELATION OF THE bello sediments at some localities took place first above, MAHANTANGO FORMATION then below, .sea level. For example, the lower beds of Eocks of the lower shale and sandstone member were the member at the Eockville quarries, about 15 miles deposited in the same transgressive sea as those of the west of the area on the Susquehanna Eiver, probably Marcellus Shale. Eelations between these stratigraphic were deposited above sea level, as shown by remains units indicate that sedimentation continued without in­ of land plants (Willard, 1939a, p. 198); but the upper beds there and elsewhere were deposited below sea level, terruption during deposition. The average grain size as indicated by brachiopod molds. in the lower shale and sandstone member, however, is The upper shale member seems to have be^n deposited slightly greater than that in the Marcellus. This charac­ upon the Montebello Sandstone Member without an teristic suggests that the source lay somewhat closer to interruption in sedimentation. It accumulated in the the report area, was more heavily eroded, or was sea as the influx of coarse elastics that had been eroded slightly higher during lower member deposition than from the Auburn promontory during Montebello time during Marcellus deposition. lessened and finally ceased. The absence of the lower member of the Mahantango Willard (1939a, p. 176-194) described a large late Formation in central Schuylkill County indicates that Middle Devonian fauna from the Mahantango Forma- STRATIGRAPHY 37

tion. This fauna indicates that the formation is cor­ lier, and Parkhead Members. The Trimmers Rock is the relative with the Skaneateles, Ludlowville, and Moscow dominant or only division of the Fort Littleton Fomna- Shales of central and western New York, that is pos­ tion of Willard that is present in the area and in the sibly is correlative with a part of the Skunnemunk region to the east. Therefore, Klemic, Warman, and Conglomerate of New Jersey and southeastern New Taylor (1963, p. 15) reclassified the Trimmers Rock York, and that it is correlative with the upper part of Sandstone as a formation in the Lehighton T^-quad- the Romney Shale of Maryland, Virginia, and West rangle, Carbon County. The authors concur with tl ?ir Virginia (Cooper, G. A., and others, 1942, chart 4). decision and consider the Trimmers Rock of the r.rea to be a formation that includes the strata between the SUSQUEHANNA GROUP Mahantango and Catskill Formations. The Trimmers Rock crops out in three belts in the A thick sequence of marine and continental rocks, area. Each of these belts is hilly and has a topographic the Susquehanna Group, principally of Late Devonian relief that averages about 200 feet, but which at plpries age, rests with apparent conformity upon the Mahan- may be slightly more than 300 feet. Localities underlain tango Formation in the area. by the formation commonly are mantled with a blo",ky Inclusion of the Upper Devonian rocks of Pennsyl­ sandstone rubble. vania in the Susquehanna Group was proposed by Ash- The largest belt of outcrop of the Trimmers RocV is ley in 1923 (p. 1106-1108). His proposal did not gain about 15 miles long and underlies the limbs and trough widespread usage for many years, but in 1959 several of the Pine Grove syncline in the Pine Grove, Swatara geologists working in the Commonwealth accepted the Hill, and Tower City quadrangles (GQ-689, 691, 698). group as a valid stratigraphic unit (Miller, J. T., and Outcrops are poor, except near the base of the formation Conlin, R. R., 1959; Arndt and others, 1959, p. 3). where there are many good exposures in borrow pit?. The Susquehanna Group, as recognized by the U.S. North of the Sweet Arrow fault zone a second belt Geological Survey, includes the strata from the top of of outcrop extends from the eastern boundary of the the Tully Limestone of Middle Devonian age to the base Swatara Hill quadrangle to a point about halfway be­ of the Pocono Formation of Early Mississippian. Where tween Beuchler and Outwood in the Pine Grove quad­ the Tully is absent, as in the report area, the base of the rangle, where it is truncated at the fault zone (GQ-689, group is defined as the top of the Mahaiitango Forma­ 691). This belt is about 0.4 to 0.5 of a mile wide. C it- tion. In the report area the group consists, m ascending crops are sparse and poor, except locally in steep-sided order, of the Trimmers Rock Sandstone and the Catskill valleys. Formation. The third belt of Trimmers Rock underlies both The Trimmers Rock Sandstone and the Catskill limbs and the crest of the Broad Mountain anticlinor- Formation represent a sedimentary cycle that consists, ium in the Klingerstown and Valley View quadrangles in ascending order, of a marine rock sequence, a transi­ (GQ-699,700). Exposures generally are poor, but along tional marine and continental rock sequence, and a con­ some valley walls several hundred feet of the formation tinental rock sequence. The gradual change from marine crop out locally. to continental sedimentation took place through several The Trimmers Rock Sandstone conformably overlies thousand feet of rock. The marine sequence is included the upper shale member of the Mahantango Formation largely in the Trimmers Rock. The transitional sequence in the area. However, about 4 miles west of the area, is embraced largely by the Irish Valley Member of the near Mandata, the Burket Black Shale Member of the Catskill, but it also includes some of the lower part of Harrell Shale intervenes, and about 8 miles west of the the Damascus Member (GQ-689,691) and an equivalent area, near Dalmatia, the upper part of the Harrell and part of the Buddys Run Member (GQ-699, TOO). The the Brallier Shale also intervene (D. M. Hoskins and continental sequence includes the middle and upper R. R. Conlin, oral commun., 1961). Detailed strati- parts of the latter members and the overlying members graphic work between these exposures and the report of the Catskill. area indicates that the Harrell and Brallier probably TRIMMERS ROCK SANDSTONE tongue out eastward into the lower part of the Trim­ mers Rock. Eastward intertonguing of the Harrel and The Trimmers Rock Sandstone, basal unit of the Brallier into the Trimmers Rock was first suggested by Susquehanna Group in the area, was named by Willard Willard (1935b, p. 39), who noted that the basal beds of (1935c) for Trimmers Rock, a prominent hill near New­ the Trimmers Rock east of the area, in Monroe County, port in Perry County. As originally defined, it included contain Hypothyridina venustula, the guide fossil of the those beds underlying the Parkhead Sandstone member Middle Devonian Tully Limestone. On the basis of this of the Jennings Formation and overlying Willard's fossil, he postulated that successively older Late Devon­ Losh Run Shale. Subsequently, Willard (1935d) rede­ ian Brallier Shale, Late Devonian Harrell Shale, and fined the unit by reducing it to a member of his Fort Middle Devonian Tully Limestone tongued eastward Littleton Formation, which, in ascending order, con­ into the Trimmers Rock. Thus, in the area, the contact sisted of tlhe Harrell, Losh Run, Trimmers Rock-Bral- between the Trimmers Rock and the upper shale mem- 38 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA ber probably is older than the Burket Black Shale Mem­ overlying Irish Valley Member of the CatsHll Forma­ ber of the Harrell and may be as old as the Tully Lime­ tion across the zone. stone. The contact is at the sharp change from shale, North of the Sweet Arrow fault zone th*, Trimmers silty shale, and siltstone of the upper shale member to Rock thickens northeastward at a rate of 27 to 33 feet very fine grained to fine-grained sandstone and siltstone per mile. Before the 30 percent structural foreshorten­ of the Trimmers Rock. ing of the Devonian rocks of the area, it probably The contact of the Trimmers Rock with the overlying thickened northeastward at an average rate of 19 to 23 Irish Valley Member of the Catskill Formation norm­ feet per mile. South of the fault zone, th«. Trimmers ally is placed at the base of the lowest red bed. Within Rock thickens northwestward at about 80 feet per mile. the area, these units intertongue at a scale so large that Structural shortening in this part of the area seems individual tongues can be shown on 1: 24,000 maps (GQ- to have been negligible, and the original rate of deposi­ 689, 691,699,700). In the core of the Pine Grove syncline tioiial thickening has not changed. (GQ-689) a discontinuous tongue of Irish Valley red Freshly exposed rocks in the formation are chiefly beds locally splits the Trimmers Rock in half. At this light olive gray, light brownish gray, olive brown, and one place, therefore, a sequence of olive and gray strata medium gray, but grays, browns, and green" are not un­ of the Trimmers Rock is shown to lie above the lowest common. Weathered rocks are largely light olive gray, red bed. Regionally, rocks at the base of the Irish Valley medium to dark gray, and brownish gray; a few are tongue to the east and southeast with successively older greenish-gray. rocks at the top of the Trimmers Rock. The scale of Most beds in the formation are tabular, but some are intertonguing is so great that much, if not all, of the cross-stratified and wedge shaped. Beds range in thick­ Irish Valley in the southeastern part of the area (GQ- ness from % inch to 10 feet and average ^bout 1 foot. 689, 691) may be the time equivalent of the Trimmers Sole markings, current laminations, crossbeds, and Rock in the northwestern part (GQ-699,700). other current-oriented sedimentary features indicate A few feet to several hundred feet of the Trimmers that the source of the elastics of the Trinmnrs Rock lay Rock Sandstone crop out at numerous places in the area. southeast and east of the area. Only one of these outcrops, north of Pine Grove on the The rocks of the Trimmers Rock consist of slightly west side of Swatara Creek, is sufficiently well exposed to moderately fossiliferous well-cementei sandstone so that a section can be measured and the lithology and micaceous siltstone and some micaceous shale. The studied (fig. 19, section 1). There, the basal part of the repetition of sandstone and siltstone beds of approxi­ formation is truncated by the Sweet Arrow fault zone, mately equal thickness is the outstanding characteristic and only 2,011 feet is measurable. Regional mapping of the formation. The sandstones are protoquartzite suggests that the original thickness of the formation at and subgray wacke with a small amount of orthoquartz- this locality was about 2,100 feet. ite. They are predominantly very fine grained; how­ Another outcrop of the Trimmers Rock, 2,259 feet ever, fine- to coarse-grained sandstone is no4- uncommon, thick, which appears to be unfaulted, lies a few miles and pebble conglomerate is present about two-thirds east of the area. The exposure is about 2.4 to 2.85 miles of a mile southwest of Twin Grove Park (GQ-698) in south of Pottsville on the east side of Schuylkill River a roadcut of the Reading Co. The sandstones are com­ in roadcuts of the Pennsylvania Railroad and a county posed of grains of common and vein quartz and sub­ road (fig. 19, section 2). The formation is not so com­ ordinate amounts of quartzite, other rock fragments, pletely exposed in this section as it is north of Pine halloysite, unidentified clay minerals, biotite, ilmenite, Grove, but the lithology is similar. muscovite, sericite, and small percentages of andesine, The thickness of the Trimmers Rock Sandstone was orthoclase, tourmaline, and zircon. Although the aver­ calculated at many places in the area. These computed age grain is subangular, the shape ranges from angular thicknesses, the thicknesses measured at the sections to well rounded. Cementing media are silica and clay shown in figure 19, and many other thicknesses deter­ with minor amounts of limonite and calcite. mined in the surrounding region were used to construct The siltstone of the Trimmers Rock contains less an isopach map of the formation (fig. 20). The Sweet quartz and more sericite and unidentified clay minerals Arrow fault zone separates the Trimmers Rock into than does the sandstone. The shale in the formation is two areas of contrasting thickness. North of the zone similar to the siltstone, except that the percentage of the formation thickens northeastward from about 1,800 sericite and clay minerals is greater. feet in the southwestern part of the area to more than The Trimmers Rock Sandstone seems to have accum­ 2,400 feet in the northeast. South of the zone it thickens ulated without interruption upon the upper shale mem­ northwestward from about 1,300 feet to more than 1,500 ber of the Maliaiitango Formation. The basal beds of feet. The contrasting thicknesses on opposite sides of the the sandstone in the area probably are laterally equiv­ fault zone probably did not develop during deposition. alent through intertonguing with the Tully Limestone, Therefore, it is likely that faulting brought into juxta­ Harrell Shale, and Brallier Shale. position parts of a depositioiial basin which previously The clastic sediments of the formation were derived were far removed one from another. This probability is from a landmass that lay east and southeast of the area, supported by a similar difference in the thickness of the possibly in New Jersey or eastern Pennsylvania. They STRATIGRAPHY 39

th of Potts

rr ill-hr : ... ^r~_^j '^= / 7 ; . . . _ . . . __ _ _ _;_

HT=rriir

: -vrfr T: ; :-.-. . . .

_ 1 '_!_ _ Covered interval . . .

Fault

TT 2011 Trimmers Rock Total thickness, in feet Sandstone

FEET 0

;

_^ '.^~' ' '

' ' ' . _: _:

...'"' ~~7 : -.'" .' 76°45' 37'30" 30' 22'30" 76°15' 40M5'

=TTTT^=-

TT 2011

^ ^ 40°30' X\ 0 5 MILES I i i I I I INDEX SHOWING LOCATION OF SECTIONS TT 2259

FIGURE 19. Columnar sections of the Trimmers Rock Sandstone. 40 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA 76°45' 76°15' 40° 45' KLINGERSTOWN VALLEY VIEW TREMONT MINERSVILLE

C° ~**0o- ^^ EXPLANATION &%&'& 2200 -20OO- vsf^ -2IOO- Isopachs Contour interval 100feet

2015 + x Measured thickness, in feet .1350 Computed thickness, in feet

~~ BERKS CO 40° SWATARA HILL 30'

FIGTTRE 20. Isopach map of the Trimmers Rock Sandstone. seem to have been deposited in a westward-regressing The uppermost gray beds of the Trimmers Rock sea that was being filled with debris from the landmass. Sandstone at any locality in the area rre laterally The repetitious interbedding of siltstone and sandstone equivalent through intertonguing east of that locality was probably caused by slight changes in the compe­ with the basal red beds of the Irish Valley Member of tency of the streams carrying sediment to the sea and the Catskill Formation. The reason for tH change in by slight changes in the competency of marine and tur­ color at the Trimmers Rock and Irish Valley contact bidity currents distributing the sediment. is not definitely known, but the following is postulated Frakes (1961) postulated that the Trimmers Kock Sedimentary features and intertonguing relations in­ was deposited exclusively by turbidity currents. He dicate that the sediment in these stratig^aphic units cites as evidence of turbidity-current deposition: graded was derived from a source east and southeast of the bedding, convoluted bedding, load casts, current lam­ area (Mclver, 1960; Frakes, 1961, fig. 1). Much of the inations, oriented plant fragments, sole markings and detritus from the source arrived at the strand line as alternating lithologies. Similar sedimentary features a red sediment. Whenever deposition was rapid, the in other parts of the United .States commonly are inter­ sediment was quickly buried and was not exposed for preted to indicate deposition by turbidity currents, but long periods to a marine reducing environment; it thus in many places they also can be interpreted to indicate retained its red color. When deposition wss slow, how­ variations in the fluvial supply of sediment and the ever, reduction of ferric iron to ferrous iron took place, marine currents depositing the sediments. The authors and the red color of the sediment was changed to gray believe that turbidity currents were active during depo­ and olive. The basal red beds of the Irish Valley prob­ sition of the formation, but they do not believe that the ably represent the oldest Upper Devonian rocks to ac­ widespread alternation of sandstone and siltstone beds cumulate so rapidly that they were buried before being over thousands of square miles was accomplished solely subjected to reduction and a consequent change in by turbidity currents. color. An extensive fauna has been reported from the Although the contact between the Trimmers Rock Trimmers Kock (Willard 1939a, p. 212-215). The and Irish Valley is placed at the lowest red bed in abundance of this fauna indicates that the sediments of the Upper Devonian sequence, marine sediments sim­ the formation accumulated in relatively shallow waters ilar to those of the Trimmers Rock were deposited as where food, oxygen, and light were plentiful. tongues in the lower parts of the Damascus and Bud- STRATIGRAPHY 41 dys Run Members of the Catskill Formation. Most red rocks are divided into members that are classified dif­ beds between these tongues, and some red beds in the ferently in the southern and northern parts of the Irish Valley Member, contain macerated plant fossils, area. In the southern part (GQ-689, 691, 698, 701) the fragments of coalified vegetation, raindrop impres­ formation is divided, in ascending order, into the Irish sions, mud cracks, and tracks that are consid­ Valley, Damascus, Honesdale, Cherry Ridge, and ered to indicate terrestrial deposition (Barrell, 1913- Spechty Kopf Members. The Honesdale Sandstone 14, p. 455, 466). The interbedded marine and conti­ Member, which tongues or wedges out northward in nental rocks in the Damascus, Buddys Run, and Irish the subsurface of the area, separates the generally Valley Members indicate that the lower part of the finer grained red beds of the Damascus from similar Catskill Formation accumulated in a generally regres­ red beds of the Cherry Ridge. Where it is absent in sive sea in which minor transgressive phases were not the northern part of the area (GQ-692, 699, 700), the uncommon. The minor transgressions probably were indistinguishable Damascus and Cherry Ridge Mem­ due to slight readjustments in the altitude of the sea bers are mapped together as the Buddys Run Member. bottom and to variations in the amount of sediment Mather (1840, p. 212-213,227-233) named the CatsHll being deposited in the sea. for the mountains in Delaware, Greene, Schoharie, Snl- At any one locality it is uncertain where continental livan, and Ulster Counties, New York. He included in accumulation began, but the intertonguing indicates it the rocks between the Onondaga Limestone and the that such accumulation began at different times in dif­ Pottsville Formation. Vanuxem (1842, p. 186-194) re­ ferent localities. It is possible that at some places the defined the Catskill to include only the rocks younger oldest continental sediments coincide with, or slightly than the Chemung Formation. During the 20th cen­ underlie, the basal red bed of the Irish Valley, but it tury, many geologists who worked in New York cHs- is more reasonable to assume that terrestrial sedimen­ cussed the Catskill, the strata it should and should not tation began later in Irish Valley time. Despite this include, and its age relations at various places. uncertainty, most geologists who have worked the Up­ Meanwhile, I. C. White (1883, p. 49-75) solved the per Devonian rocks of eastern Pennsylvania consider problem of the base of the Catskill in Pennsylvania to the basal red bed of the Irish Valley to mark the upper the satisfaction of most geologists who have studied limit of wholly marine deposition which began in the formation there by placing the lower contact at Silurian time. the lowest red bed. He assigned the marine strata be­ The Trimmers Rock Sandstone contains an early low the lowest red bed to the Chemung (Trimmers Late Devonian fauna (Willard, 1939a, p. 211-215; Rock Sandstone of this report) and the transitional Cooper, G. A., and others, 1942, chart 4). The Harrell red- and olive-hued alternating marine and continental and Brallier Shales of central Pennsylvania, the beds above it to his transitional Catskill-Chemung Woodmont Shale of western Maryland, and the Son- Group (Irish Valley Member of this report). yea and Genesee Formations (de Witt and Colton, Lesley (in Lesley and others, 1892-95, p. 1601-1607), 1959) of central New York contain a similar fauna. in his summation of the , in­ The regional intertonguing of the Trimmers Rock cluded White's Catskill-Chemung Group in the Crts- with underlying rocks and the local occurrence of the kill, which he reduced in rank from a group to a fossil Bypothyridina venustida east of the area indi­ formation. He followed White in placing the base of cate that the basal beds of the formation are equivalent the Catskill at the base of the lowest red bed. to the Middle Devonian Tully Limestone (Willard, The problem of the upper contact of the Catskill v^as 1935b, p. 39). The intertonguing between the rocks of solved by Lesley (1876) and Franklin Platt and W. G. the formation and overlying rocks is suggestive that Platt (1877, J). xxvi) when they named the Pocono Sand­ the upper beds of the formation are equivalent with stone (Pocono Formation of this report) and stated part, and perhaps with all, of the Irish Valley Member that the gray rocks of this unit overlay red rocks of the of the Catskill. Catskill. The precise position of this contact at many localities has been the subject of much discussion; how­ DEVONIAN AND MISSISSIPIAN ROCKS ever, Lesley's and the Platts' definition of the CatsHll and Pocono contact generally has been accepted. I. C. CATSKILL FOKMATION White (1883, p. 49-52) states that his Pocono-CatsHll The Catskill Formation of Late Devonian and Transition Group (probably the Spechty Kopf Member Early Mississippian age is the upper division of the of this report) was a transitional gray and red rock se­ Susquehanna Group. It includes the rocks between the quence between the gray Pocono and the red Catskill. top of the Trimmers Rock Sandstone and the base of Lesley, in 1892 (Lesley and others, 1892-95, p. 1601- the Lower Mississippian Pocono Formation. These 1607), included this unit in his Catskill Formation, thus 42 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA placing the top of the Catskill at the top of the upper­ to determine the structural features and stratigraphic most red bed, the contact recognized in this report. changes that are shown on quadrangles GQ-689, 691, Williams (1887, p. 27) and Hartnagel (1912, p. 86) 692,699,700. recognized that from east to west the basal beds of the The member generally underlies a subdued rolling Catskill overlay successively younger beds in the strati- upland that has shallow steep-sided valleys. The amount graphic sequence. However, it remained for Chadwick of relief locally is as much as 300 feet. (1933a, b; 1935a) and Willard (1933, 1935b, 1936, The lower and upper beds of the Irish Valley are 1939a) to comprehend and describe the intertonguing of conformable with underlying and overlying strata. The the Catskill with strata ranging in age from Middle member intertongues with the underlying Trimmers Devonian in New Jersey and eastern New York to latest Rock Sandstone and the overlying Buddys Run or Devonian in western Pennsylvania and southern New Damascus Members at a scale large enough to be shown York. on 1:24,000 maps. The stratigraphic relations between IRISH VALLEY MEMBER the Irish Valley and the Trimmers Rock sre described The Irish Valley Member was named by Arndt, in the chapter about the latter formation. The only part Wood, and Trexler (1962, p. C35) for a valley near of that description reemphasized here is that the con­ Shamokin, Northumberland County, Pa. The member tact between these units is at the base of the lowest red includes the strata between the Trimmers Rock Sand­ bed in the Upper Devonian rock sequence. The contact stone and either the Damascus or Buddys Run Member of the Irish Valley with overlying rocks is at the horizon of the Catskill Formation. above which the red beds dominate and bek w which red Geologists who have worked in eastern Pennsylvania and olive-gray beds are intercalated the percentage of classified the strata assigned to the Irish Valley Member red beds decreasing stratigraphically downward. as follows: I. C. White (1883, p. 63-67) assigned them Both the upper and lower contacts of the Irish Valley to his Catskill-Chemung Group. A few years later Les­ Member gradually rise westward in the Devonian se­ ley (in Lesley and others, 1892-95, p. 1594-1607) placed quence by intertonguing. It is possible tl:at much, if them at the base of the Catskill. Barrell in 1913 (1913- not all, of the member in the southeastern part of the 14, p. 455-458) assigned the upper beds of the unit to area is the time equivalent of the Trimmers Rock Sand­ his Catskill-Chemung transition beds and the lower stone in the northwestern part. Similarly, the lower beds to his Chemung Group. Willard (1939a, p. 257- beds of the Damascus Member in the southeastern part 307) apparently did not recognize the strata included may be time equivalents of the Irish Valley of the north­ in the Irish Valley Member. According to his figure 72 western part. and the text of his report (p. 291-295), continental red The Irish Valley has been measured and described beds of his Damascus Red Shale (Damascus Member at a locality a short distance north of Pine Grove on of the Catskill in this report) rest upon gray beds of the west side of the Reading Railroad tracks and Swa­ the marine Trimmers Rock Sandstone in the vicinity of tara Creek (fig. 21, section 1). It has also been measured the area. It, therefore, appears that he overlooked the east of the area at localities north of Cresrona (fig. 21, interbedded red and olive-gray marine and continental section 2) and south of Pottsville (fig. 21, section 3). rocks of the Irish Valley Member. An isopach map of the member, constructed from these The Irish Valley Member crops out on the flanks and measurements and from many other thicknesses that crest of the Broad Mountain anticlinorium in the were calculated across the outcrop belts (f g. 22), indi­ Klingerstowii and Valley View quadrangles (GQ-699, cates that the Irish Valley thickens northwestward from 700). A second, less extensive, belt of outcrop lies north a minimum of 185 feet near Pine Grove to a maximum of the Sweet Arrow fault zone in the Pine Grove and of 2,250 feet in western Schuylkill and southern North­ Swatara Hill quadrangles (GQ-689, 691). A third belt umberland Counties and then thins in the same direction is on the limbs and trough of the Pine Grove syncli'ne to about 1,800 feet north of Hooflander Mountain. The in the eastern part of the Swatara Hill quadrangle member is 900± feet thick south of the !?weet Arrow (GQ-689). fault zone and only 185 to 300 feet thick a short distance Exposures in the various belts of outcrop of the Irish north of the zone. This great difference in thickness Valley are usually limited to natural cuts along steep across the zone suggests that faulting has brought close valley walls and to manmade cuts along roads and rail­ together rock sequences that originally lay far apart. roads. Despite the scarcity of outcrops, the belts are A similar difference exists across the zone in the Trim­ easily mapped at most places by tracing alternating mers Rock Sandstone and also suggests considerable bands of red and olive-gray varicolored float. Delinea­ foreshortening. The Irish Valley thickens northward at tion of these bands during fieldwork made it possible an average rate of about 180 feet per mile north of the STRATIGRAPHY 43

2 3 North of Pine Grove, North of Cressona, South of Pottsville, Schuylkill County Schuylkill County Sandstone Schuylkill County EXPLANATION

Covered interval

3399'

Percent 0 25 50 75 1100 Approximate percentage of red beds; covered intervals based on float

m Marine fossils

p Plant fossils

22'30" 76°15' 45' ^ ^ O" /" ^

MILES

INDEX SHOWING LOCATION OF SECTIONS

FIGURE 21. Columnar sections of the Irish Valley and Damascus Members of the Catskill Formation. 316-3,52 O 69 44 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA

76°45' 76°15' 40° 45' KLINGERSTOWN VALLEY VIEW TREMONT M1NERSVILLE .1800 1900.

EXPLANATION

-500- Isopachs Contour interval 500 feet X 185 Measured thickness, in feet ,200±

Trace of 200± Computed thickness, in feet Sweet Arrow fault ^'

.,185 800-900.

Isopachs south of Sweet Arrow fault not shown because of insufficient data

- " BERKS CO 40" LYKENS TOWER CITfr PINE GROVE^ SWATARA HILL 30' 10 MILES I

FIGURE 22. Isopach map of the Irish Valley Member of the Catskill Formation. fault zone in Schuylkill and Dauphin Counties. Before siltstone contain the same mineral assembHges as the the folding and faulting, which shortened the Devonian coarser grained rocks but the amount of mica minerals rocks of the area about 30 percent, the member thickened and unidentified clay minerals increases ss the grain northwestward at a rate of about 125 feet per mile. size decreases. Fresh and weathered sandstones in the Irish Valley The depositional environment of the Irish Valley was Member are mainly light olive gray and pale brown, discussed in the description of the Trimmers Rock Sand­ but light greenish gray, greenish gray, light brownish stone and will not be discussed at great length here. gray, brownish gray, pale red, and dusky yellows are The rocks of the Irish Valley are chiefly red and common. The siltstone is predominantly grayish red, olive gray. They are believed to have accumulated in pale brown, and light olive gray, but some is light to part, in a westward regressing sea; in part, at the medium gray, light greenish gray, and yellowish gray. margins of the sea; and perhaps in part, in deltas and The shale is pale to olive gray, greenish gray, yellowish on flood plains. Most of the sediment that accumulated gray, yellowish brown, and pale red. at or below sea level probably was red when it arrived Beds of the Irish Valley are 2 inches to 50 feet thick at the strand and retained its color because deposition and average 3 feet. Most are tabular; but a few are and burial were rapid; however, when deposition and irregular and wedge shaped, and a very few are cross burial were slow, reduction changed the red to olive stratified with small-scale planar crossbeds. gray. The coarser grained rocks of the Irish Valley are Marine fossils in the olive-gray beds and in some red chiefly protoquartzite and subgraywacke. They are beds of the member suggest that the sea bottom sup­ composed in large part of grains of common and vein ported prolific life. The interbedding of marine and quartz and fragments of quartzite with lesser amounts continental rocks further suggests that thir marine life of biotite, muscovite, sericite, tourmaline, and zircon flourished in shallow waters near the shore, ^hese waters grains; rock fragments of schist and slate; unidenti­ were generally regressing to the west because of a grad­ fied clay minerals; and a very small amount of ande- ual filling of the depositional basin with sediment from sine and orthoclase grains. Grain size ranges from very a rising landmass east of the area. Minor transgressions fine to fine and averages very fine. Cementing materials took place from time to time and probably were caused are silica, limonite, hematite, and clay. The sorting is by temporary decreases in the supply of detritus brought poor to excellent but is usually good. The shale and into a generally sinking basin. As time went on, how- STRATIGRAPHY 45 ever, the supply of detritus increased intermittently, so The Damascus Member crops out. in two belts in the that by the end of Irish Valley sedimentation, the sea area. The larger of these lies south of Second Moun­ was largely forced west of the area. tain (GQ-689, 690, 691, 698); the smaller is in the Most geologists have believed that wholly marine De­ upper reaches of Powell Creek valley (GQ-701). The vonian deposition ended in the vicinity of the area with lower part of the Damascus in both belts underlies a the end of Trimmers Eock deposition. Similarly, even gentle rolling subdued topography. Stream valleys are though marine tongues are present in the Buddys Run not dissected deeply, and this part of the unit is com­ and Damascus Members, the top of the Irish Valley monly farmed intensively. The upper part of the mem­ Member is believed generally to mark the final regres­ ber in the belt south of Second Mountain underlies steep sion of the Devonian sea. heavily wooded slopes, which are dissected by transverse The fauna of the Irish Valley Member has not been valleys only at wind and water gaps. The upper part of studied, but because the member tongues with the over­ the unit in Powell Creek valley underlies gentle to steep lying Buddys Run and Damascus Members and with moderately dissected heavily wooded slopes. the underlying Trimmers Rock Sandstone, it can be The lower contact of the Damascus with the Irish assumed that the age is also early Late and middle Late Valley Member is difficult to pick because it is in a zine Devonian (Cooper, G. A., and others, 1942, chart 4). of intertonguing. Individual tongues of Damascus or Regional correlations of the Irish Valley into other Irish Valley strata at many places are large enough so parts of Pennsylvania are uncertain because of the in- that they can be shown on 1:24,000-scale maps (GO- tertonguing relations of the member and because the 689, 690, 691, 698). In general, the contact is arbitrarily stratigraphic relations of the lower part of the Catskill placed at the horizon above which the main red bed Formation elsewhere in the Commonwealth are im­ sequence of the Damascus predominates over the red and perfectly understood. The Irish Valley, therefore, is olive-gray beds of the Irish Valley. The stratigraphic correlated only tentatively with part and perhaps all position of this contact rises gradually from east to v^est of the Chemung Formation of central Pennsylvania, by intertonguing. with the Dellville Sandstone 'and Kings Mill Sandstone The upper boundary of the Damascus on the southern and Shale of Claypole (1885) of Perry County, and slope of Second Mountain (GQ-689, 690, 691, 698) is with the Shohola Formation of Willard (1936) of covered at most localities, but is placed where red and northeastern Pennsylvania and southeastern New York. gray fine-grained rocks of the member are overlain by The local discontinuous tongue of the Irish Valley near red and gray rock of the basal conglomeratic sequence the middle of the Trimmers Rock Sandstone in the Pine of the Honesdale Sandstone Member. In the southern Grove syncline (GQ-689) may be laterally correlative part of the Lykens quadrangle (GQ-701) this contact is with the Walcksville Sandstone Member of the Catskill not exposed and is arbitrarily placed at the base of a in Carbon County (Klemic and others, 1963, p. 26-27), sequence of medium-grained to very coarse grained which, in turn, may be correlative with the Analomink sandstone of the Honesdale and at the top of grayish- Red Shale of Willard (1935d) in Monroe County. red fine-grained to very fine grained sandstone and si ?\le

DAMASCUS MEMBER of the Damascus. The Damascus Member is best exposed within the rrea The lowest persistent red division of the Catskill For­ north of Pine Grove (fig. 21, section 1). Several miles mation on the Pocono Plateau of northeastern Pennsyl­ east, of the area and north of Cressona on the vest vania was named the Damascus Red Shale by Willard branch of the Schuylkill River it is relatively well ex­ (1936, p. 571, 584-585) for exposures near Damascus. posed (fig. 21, section 2), and a short distance farther After an extensive field reconnaissance on the Pocono east and south of Potitsville on the main branch of the Plateau (Harry Klemic, oral commun., 1959), Klemic, Schuylkill River it is less well exposed (fig. 21, section Warman, and Taylor (1963, p. 28-29) accepted Wil- 3). lard's correlation of the Damascus into the Lehighton In addition to the measured sections, the thickness quadrangle at the east end of the Southern Anthracite has been calculated at many places in the member. Tl <^se field. The authors also tentatively accept the Damascus calculated and measured thicknesses and the thickness as a member of the Catskill Formation in the southern part of the area. The term "red shale*' is abandoned as at places outside the area were used to compile figure 23, a lithologic modifier because the member at many lo­ an isopach map of the member. The Damascus is not calities consists in large part of gray, olive, green, and shown northwest of a line where the Honesdale Sand­ brown sandstone, siltstone, and shale. As used in this re­ stone Member is inferred to wedge out, or south of the port, the Damascus Member includes all strata lying Sweet Arrow fault zone where the member has been re­ between the Irish Valley and Honesdale Members. . moved by erosion. Between the fault zone and the wedge 46 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA 76°45' 76" 15' 40° 45' KLINGERSTOWN VALLEY VIEW ^x" TREMONT X* Area in which Damascus Member is pot distinguishable

Line along which Honesdale Sandstone Member is inferred to wedge out EXPLANATION -4500- Isopachs Contour interval 500 feet

33?9 X Measured thickness, in feet ,4500 Computed thickness, in feet

BERKS CO 40° SWATARA HILL 30' 10 MILES

FIGURE 23. Isopach map of the Damascus Member of the Catskill Formation. out of the Honesdale, the Damascus thins northward The beds of the Damascus range in thick less from y± from 4,650d= feet near the zone to slightly more than inch to 15 feet and average about 3 feet. Most sand­ 2,500 feet at the wedge out at an average rate of 190 stone beds are about 3 feet thick, but many are much to 220 feet per mile. The rocks of the member were tele­ thicker. The average siltstone and shale bed is about 1 scoped about 30 percent during folding and faulting, foot thick, but many are as thin as y% inch or as thick and before deformation they probably thinned north­ as 15 feet. Slightly more than 50 percent of the member ward at an average rate of about 135 to 155 feet per mile. is tabular bedded, and the remainder is wedge bedded. The sandstone of the Damascus Member is largely Many beds are cross stratified with simple and planar grayish pink to grayish red, light olive to olive gray, cross-strata, which generally are less than 1 foot long pale brown, and dusky yellow. Some is light to dark but which locally may be as long as 5 feet. Cross-strati­ brownish gray, pale to dark yellowish brown, greenish fication is more common in the upper and middle parts gray to dark greenish gray, and greenish to moderate of the member than in the lower. Graded bee1 ding is com­ yellow. Conglomerate is pale to dark yellowish brown, mon and reverse grading is rare. grayish red, and dusky yellow. The siltstone, in order of Many shale and siltstone beds are internally con­ decreasing abundance, is grayish red, pale brown, light torted. In most places the contortions developed after to olive gray, medium gray and light to brownish gray. consolidation and were caused by structural adjustments The shale is largely light to olive gray and grayish red, of more competent strata moving differentially against a few beds being pale brown, light to brownish gray, the less competent shale and siltstone. In a few local­ and light to dark greenish gray, and dusky yellow. ities, however, the contortions developed p.fter deposi­ Grayish-red and pale-brown rocks compose about 50 to tion and before consolidation. 75 percent of the member, and rocks of other colors Plant fragments, raindrop impressions, and mud constitute the remainder. The percentage of red beds in cracks are preserved in many sandstone p-nd siltstone the member decreases eastward from about 75 percent in beds. Kipple marks, whose crests generally trend north­ the southeastern part of the Tower City quadrangle eastward, are common in the upper parts of some silt- (GQ--698) to about 50 percent at the east border of the stone and fine-grained sandstone beds. Swatara Hill quadrangle (GQ-689), and is only about Kock types of the Damascus Member are, in decreas­ 40 percent east of the area near Cressona (fig. 21, sec­ ing order of abundance, shale, sandstone, siltstone, and tion 2) and Pottsville (fig. 21, section 3). conglomerate. The sandstone is predominantly fine STRATIGRAPHY 47 grained, but much is very fine to medium grained. mentary features, such as mud cracks, raindrop impres­ Coarse-grained and very coarse grained sandstone is sions, plant rootlets, and the lack of marine fossil? in present throughout the unit, whereas conglomerate is most beds. He recognized, however, that the sea trans­ confined to the upper part. The average diameter of the gressed and regressed many times upon the delta in pebbles in the conglomerate is about three-eighths of early Catskill time, but from the uniformity of red an inch, and the maximum is as large as 2 inches. shale (red beds?) in the formation, he concluded that Although most of the sandstone is subgraywacke, a the delta was well drained when not beneath marine considerable amount is protoquartzite and graywacke. waters. He also believed that the red color of most Cats- The mineral assemblages of the three rock types are kill rocks was due to sea-level oxidation during and similar; the principal difference between protoquartzite after deposition and that the rocks were not red before and graywacke is an increase in the amount of feldspar, that time. In addition, Barrell postulated that the gray clay minerals, micaceous minerals, and rock frag­ beds of the Catskill accumulated in the sea. ments such as quartzite, schist, phyllite, and slate in When the large number of gray beds in the Damascus the graywacke and a proportionate decrease in vein Member are considered, the theories advanced by Par- and common quartz. The principal mineral constituents rell demand that the sea fluctuate back and forth across of all types of sandstone are grains of vein and common the delta many hundreds of times. Barrell's concept of quartz and fragments of quartzite. Accessory minerals sea-level fluctuation probably is incorrect because most are grains of muscovite, tourmaline, zircon, ilmenite, of the gray beds contain plant fossils and only a few magnetite, leucoxene, sericite, unidentified clay min­ contain marine fossils. An alternate postulate, here, of­ erals, and andesine and orthoclase altering to clay. In fered may be more nearly correct. Much of the sediment addition, there are considerable but greatly variable of the Damascus was deposited on a well-drained coastal quantities of rock fragments of chert, schist, phyllite, plain or above sea level 011 coalescing deltas or alluvial and slate. Feldspar is present in small quantities fans and most probably was red at the time of deposi­ throughout the member but is more common in the mid­ tion. When the sediment was deposited and buried dle part. The matrix consists chiefly of sericitic material rapidly, it retained its red color; but if deposition was and unidentified clay minerals with varying amounts of followed by slow burial and if the area of deposition hematite and limonite. Many red sandstone beds contain was poorly drained, the sediment underwent reduction as much as 15 percent hematite and limonite. The sort­ and the color was changed to gray. The following illus­ ing is commonly fair to good in the protoquartzite but trates the alternate postulate. In the south-central is generally poor in the subgraywacke and graywacke. part of the area, where the member is composed of about Most quartz grains are subangular to subrounded, but 75 percent red beds, sediment probably accumulate-! in well-rounded quartz grains are relatively common. The large part on a well-drained coastal plain, on coalescing cements in the nonred sandstone are largely silica and deltas or on alluvial fans where reducing conditions, clay, but in the red sandstone the cement is largely possibly in swamps or lakes, prevailed only about 25 hematite. percent of the time. In the eastern part of the r.rea, The mineral assemblages of the siltstone and shale where the member consists of about 50 percent red beds of the member correspond to those of the three types and farther east where it consists of about 40 percent of sandstone. The essential difference is an increase in red beds, sediment probably accumulated about 50 to the relative percentage of clay and micaceous minerals 60 percent of the time in a poorly drained environment, as the grain size decreases. Many red siltstone and shale possibly in swamps or lakes. beds contain as much as 15 percent hematite and limo­ The marine fossils in some red and many gray beds nite as cementing and interstitial material. in the Damascus show that Barrell was not correct in The pebbles of the conglomerate are largely white stating that the red versus gray color also indicates in and gray vein quartz with considerable amounts of all places the dividing line between subaerial or marine quartzite and minor amounts of schist, phyllite, slate, deposition. Because the red and gray colors were not and shale. precisely related to subaerial or marine deposition, it Most of the lower part of the Damascus Member accu­ is necessary to rely upon sedimentary features and fos­ mulated above sea level, but a few transgressions of sils as well as color when attempting to determine the the sea are recorded by thin tongues of olive-gray and environments of Damascus deposition. red beds containing marine fossils. The upper part was The sedimentary features and fossils of the lower deposited under wholly continental conditions. part of the Damascus indicate deposition upon a coastal Barrell (1913-14, p. 464-466) stated that the Catskill plain in coalescing deltas, across which the sea occa­ was deposited on a subaerial plain where deltaic condi­ sionally transgressed. Sedimentary features and p T ant tions prevailed. His conclusion was based upon sedi­ fossils in the upper part of the member indicate accu- 48 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA mulation on a coastal plain dotted with swamps, lakes, tude is remarkably even. The two resistent ledges com­ and meandering rivers. monly form rock walls that rise as much as 50 feet above The exact age of the Damascus Member is not known the adjacent less resistent rocks. because its fossils have not been studied, but its strati- In the southern part of the Lykens quadrangle the graphic relations with other members of the Catskill member is considerably thinner than on Second Moun­ suggest that it is of middle Late Devonian age (Cooper, tain. It underlies a rough and steej) terrain, but because G. A., and others, 1942, chart 4). it is thinner than on Second Mountain and because the Correlations of the Damascus are difficult. Because dip is gentle, the relief is considerably less of intertonguing, the lower beds of the member are The lower contact of the Honesdale on Second Moun­ laterally equivalent in westerly directions with the tain is covered at most places. It is at the horizon below upper beds of the Irish Valley. For the same reason, which the red and gray sandstone, siltstone, and shale they may be correlative with parts of the Chemung of the Damascus predominates and above which the Formation and the Trimmers Rock Sandstone farther basal red and gray conglomeratic sandstone and con­ west in central Pennsylvania, The rest of the member glomerate of the Honesdale dominates. is correlative with the lower part of the Buddys Run The upper contact on Second Mountain is covered at Member. Other correlations are uncertain, but Willard most places, but where exposed, it is at the top of the (1939a, p. 251-252, 292) states that the Damascus is uppermost resistent conglomeratic sandstone and is equivalent to the Canadaway Group of Chadwick overlain by less resistent beds of red and gray sand­ (1935b) in Bradford and Tioga Counties, Pa. stone, shale, and siltstone of the Cherry Ridge Member. The Honesdale is not fully exposed anywhere in the HONESDALE SANDSTONE MEMBER area. The upper part crops out at Mill CreeV Gap (fig. The Honesdale Sandstone Group was named by I. C. 24, section 1) in Second Mountain, and the upper and White (1881, p. 66-69,132,140) for exposures at Hones- lower parts are exposed in Swatara Creek Gap in Sec­ dale in Wayne County. Willard (1939a, p. 288-291), ond Mountain (fig. 24, section 2). Two other sections many years later, reduced the Honesdale Sandstone to of the member are partly exposed to the east of the area. a formation in his Catskill Continental Facies. Both The closest of these is at West Branch Gap in Second Willard and White correlated the unit with beds in the Mountain (fig. 24, section 3); the other is about 1 mile vicinity of the report area. Harry Klemic Warman, and farther east at Schuylkill River Gap (fig. 24, section 4). Taylor (oral commun., 1959), during an extensive field An isopach map of the member (fig. 25) was constructed reconnaissance on the Pocono Plateau, tentatively from the thicknesses measured at these localities and accepted the correlation of the Honesdale into the from thicknesses calculated at many places in the area Lehighton quadrangle at the eastern end of the South­ and the surrounding region. The Honesdale thins or ern Anthracite field (Klemic and others, 1963, p. 30). wedges out in the subsurface of the northern part of The Honesdale is here accepted tentatively as the the area. The line of zero thickness shown in figure 25 Honesdale Sandstone Member of the Catskill Forma­ was drawn as far northward as possible in the subsur­ tion in the southern part of the area. It includes the face to keep the rate of northward thinning to a mini­ strata lying between the Damascus and Cherry Ridge mum. As shown, it lies just south of the Catskill outcrop Members. belt on Mahantango Mountain. The Honerdale thins The Honesdale crops out in two belts in the area. The northward at average rates of about 60 to 100 feet per larger of these belts underlies the southern crest of Sec­ mile in the western and central parts of the area, re­ ond Mountain in the Tower City, Pine Grove, Swatara spectively. The Acadian and Appalachiar orogenies Hill, and Minersville quadrangles (GQ-689, 690, 691, are believed to have shortened the Devonian rocks of 698). The smaller belt occupies a part of the upper head­ the area about 30 percent. Before deformation, the mem­ waters of Powell Creek in the southern part of the ber apparently thinned northward at average rates of Lykens quadrangle (GQ-701). about 40 to 70 feet per mile in the same parts of the In the larger belt the Honsedale forms the southern area. crest of Second Mountain. The southern crest commonly consists of two subcrests with an intervening swale. The Most freshly exposed rocks of the Honesdale are pale subcrests are underlain by resistant and laterally per­ red; others are grayish red and pale brown; and a few sistent ledges of conglomerate and conglomeratic sand­ are grayish pink, light to dark gray, brovmish gray, stone. The intervening swale is underlain by less resist- greenish gray, olive gray, grayish black, gra yish green, ent conglomerate, conglomeratic sandstone, sandstone, pale to dark yellowish brown, and pale to yellowish siltstone, and shale. The topography of the crestal area orange. Weathered rocks are predominant!^ pale red, locally is rough and steep, although regionally its alti­ but a few are grayish red, grayish pink, light to dark STRATIGRAPHY 49

Mill Creek Gap, Schuylkill County West Branch Gap, Schuylkill Gap, Second Mountain, Second Mountain, Schuylkill County Schuylkill County

Swatara Creek Gap, Second Mountain, Lebanon County

FEET 0 - - P

500

Damascus EXPLANATION

1000 I

76°45' 37'30" 30' 22'30" 76°15' 40° 15'

Covered interval 37' 30" 100 Approximate percentage of red beds; covered in­ tervals based on float Unconformity 40° 30' 5 MILES , , , , 1 Plant fossils INDEX SHOWING LOCATION OF SECTIONS Siltstone

FIGUBE 24. Columnar sections of the Honesdale, Cherry Ridge, and Spechty Kopf Members of the Catskill Formation. gray, greenish gray, grayish green, olive gray, brownish thickness pattern shown in figure 25 which seemingly gray, pale to dark yellowish brown, and grayish black. indicates that the source lay somewhat more to the south. Many beds of the Honesdale are crossbedded with Bedding forms are tabular and wedge shaped in about simple and planar cross-strata 6 inches to 20 feet long. equal proportions. Bedding thicknesses range from These crossbeds and sparse ripple marks indicate that about 2 inches to 10 feet, and the average bed is about the depositing currents flowed from the sourtheast and 2 feet 6 inches thick. east. This current pattern disagrees slightly with the The rocks of the Honesdale are predominantly con- 50 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLV1ANIA

76°15'

EXPLANATION -500- -600- I^opachs Contour interval 100 feet 600 x Measured thickness, in feet fOO* Computed thickness, in feet

FIGUBE 25. Isopach map of the Honesdale Sandstone Member of the Catskill Formation (shaded where al glomerate, conglomeratic sandstone, and coarse sand­ ments of schist, phyllite, and slate. Most of the rocks stone. Fine-grained sandstone, siltstone, and shale con­ contain considerable quantities of sericite g nd unidenti­ stitute only a small part of the member. fied clay minerals and small amounts of zircon and Conglomerate is concentrated largely in the upper tourmaline. and lower parts of the member. Many conglomerate Generally, sorting in the Honesdale is poor to fair. beds are graded and contain pebbles whose maximum Grains range from angular to well rounded and average diameters range from y2 to 2 inches. These clasts consist subangular. Some quartz and chert grains are excep­ largely of milky and gray vein quartz with lesser quan­ tionally well rounded and may represent c'e.itritus from tities of gray and varicolored quartzite, gray and black preexisting sedimentary rocks. In the coprser elastics chert, schist, phyllite, and slate. The matrix of the of the member, the margins of a large percentage of conglomerate is largely coarse to very coarse grained; the quartz grains are deeply sutured, probably because in some places, however, it is fine to medium grained. of pressure solution. In the finer elastics suturing is The basal few inches of some conglomerate beds contain conspicuously absent, probably because individual numerous clay galls and shale fragments. The sandstone in the Honesdale ranges from very grains commonly are surrounded completely by a coarse grained to very fine grained with the predomi­ matrix of clay, hematite, and sericitic material. The nant grain size being fine to medium. Much of the silt- cements are silica, hematite, sericitic material, and un­ stone is sandy, and the shale is commonly silty. identified clays. Many of the sandstone and conglom­ The rocks of the Honesdale are similar mineralogi- erate beds are slightly to moderately ferruginous. Al­ cally, varying only as to the amounts of specific min­ most all the shale and siltstone beds are highly erals, grain size, and iron content. They range in ferruginous, containing 5 to 15 percent hematite. composition from rocks allied with the graywacke clan The sediments of the Honesdale are believed to have to rocks allied with the protoquartzite clan. Most of the accumulated a short distance downstream from a fall coarser grained rocks are subgraywacke, and the finer line where steep gradient streams flowing from a high­ grained ones are chiefly protoquartzite. The principal land area became low-gradient streams flowing upon mineral grains in the three types of rock are common a flood plain. The rapid northward thinning of the quartz, vein quartz, and quartzite. Accessory minerals Honesdale indicates that during deposition the fall are chert, leucoxene, hematite, and muscovite and frag­ line did not shift a great deal geographically. STRATIGRAPHY 51

The conglomerate in the Honesdale represents the tainty by only tentative acceptance of the Cherry Ridge coarse detritus eroded from a highland source known in the Lehighton quadrangle (Klemic and others, 1963, as Acadia, to the east and southeast of the area. The p. 33). It is here tentatively accepted as a member of the scattered conglomerates in the upper part of the Catskill Formation in the area. The Cherry Ridge Damascus indicate that erogenic movements marking Member includes the strata between the Honesdale the first major pulsation of the Acadian orogeny prob­ Sandstone Member and Spechty Kopf Member. Where ably uplifted Acadia during the later part of Damascus the latter is absent, the top of the Cherry Ridge is the sedimentation. Acadia had existed as a low source area unconformity at the base of the Pocono Formation. for a considerable time before orogenic uplifting and The Cherry Ridge Member crops out in two' belts had contributed sediments to rocks as old as the Trim­ where it is poorly exposed. The larger of these belts mers Rock Sandstone. During Honesdale sedimentation lies between the northern and southern crests of Second it was so strongly uplifted that streams draining from Mountain in the southeastern part of the area (GQ-689, it could transport pebbles and cobbles. The abundance 690, 691, 698). The smaller belt is in the upper head­ of these clasts in the upper and lower parts of the waters of Powell Creek valley in the southern part of Honesdale suggests that the uplift consisted of two the Lykens quadrangle (GQ-701). phases or periods with an intervening period of rela­ Along Second Mountain the outcrop belt of the mem­ tive quiescence. The abrupt transition from the sand­ ber is a narrow shallow topographic swale that is stone, siltstone, shale, and fine conglomerate in the largely surfaced by talus from the Honesdale and underlying Damascus Member to the coarse conglom­ Spechty Kopf Members and the Pocono Formation. erates in the Honesdale indicates that development of The swale deepens near each wind and water gap and a mountainous terrain in Acadia was relatively rapid. locally becomes a deep narrow valley that parallels the The rapid change from coarse Honesdale detritus to trend of the mountain. It also deepens greatly where fine Cherry Ridge detritus also indicates that the up­ the Beuchler and Blackwood faults offset the mountain. lifted part of Acadia apparently was eroded rather In the southern part of the Lykens quadrangle, the quickly. The relatively small size of the Honesdale Cherry Ridge underlies a topographic swale on the wedge of sediments in eastern Pennsylvania suggests, flanks and crest of the Joliet anticline between a low in addition, that the size of the uplifted mountain ridge held up by the Honesdale and a high ridge formed region probably was rather small. by the Spechty Kopf Member and the Pocono Forma­ The only fossils preserved in the rocks of the mem­ tion. The topography near the ridge of Honesdale ber are fragments of plants that have not been studied. Sandstone Member is characterized by moderate to The age of these rocks is believed to be middle Late or gentle slopes, but is steep, rough, and talus covered on late Late Devonian because of the stratigraphic posi­ hillsides lying beneath the Spechty Kopf. tion of the member in the Catskill Formation and be­ The contact between the Cherry Ridge Member and cause Willard (1939a, p. 281) correlated the Honesdale the underlying Honesdale is covered at most places with part of the Canadaway Group of Chadwick along Second Mountain. Where exposed, it is at the (1935b, p. 351). Within the area the member is cor­ top of the uppermost resistant conglomerate or sand­ relative with the middle part of the Buddys Run Mem­ stone ledge of the Honesdale and at the base of much ber; to the west it is correlative with the Clarks Ferry less resistant beds of red and gray sandstone, siltstone, Member of Dyson (1963). and shale of the Cherry Ridge. In the southern part of the Lykens quadrangle the contact is covered, but it is CHERRY RIDGE MEMBER believed to be where resistant red conglomerate and The name Cherry Ridge Group was applied by I. C. sandstone beds are overlain by less resistant red beds White (1881, p. 64-66) to a sequence of five strati- The Cherry Ridge Member in the Lykens quadrangle graphic units exposed near Cherry Ridge in Wayne and on Second Mountain west of the Beuchler fault, is County. As defined by White, the group included the overlain with apparent conformity by the Spechty Kopf strata lying between his Honesdale Sandstone Group Member. The contact is not well exposed at any point, and his Elk Mountain Lower Sandstone. Willard but it is gradational and is arbitrarily placed where (1936, p. 577-578) changed the name from Cherry red beds of the Cherry Ridge are succeeded by gray Ridge Group to Cherry Ridge Red Beds. Both White and olive beds of the Spechty Kopf. and Willard correlated the Cherry Ridge from the type The Cherry Ridge is overlain unconformably by the locality into the vicinity of the Southern Anthracite Pocono Formation in the southeastern part of the re­ field. Harry Klemic and others (oral commun., 1959) port area. The unconformity is an erosion surface that in a reconnaissance study of the Pocono Plateau sub­ developed in Early Mississippian time during a late stantiated the correlation, but they indicated uncer­ phase of the Acadian disturbance (Trexler and others, 52 GEOLOGY, SOUTHEKN ANTHRACITE FIELD, PENNSYLVANIA 1961). This ancient erosion surface truncates the uncertainty as to where the pre-Pocono erosion sur­ Spechty Kopf Member a few hundred feet west of the face truncated the Spechty Kopf and be^an eroding Beuchler fault (GQ-691). From the point of truncation into the Cherry Ridge. If the general tl ickness pat­ eastward on Second Mountain, the Cherry Ridge is un- tern is approximately correct, the CHrry Ridge conformably overlain by the Pocono Formation. Beds thickens northwestward at an average rate of about 75 near the unconformity are generally covered by talus feet per mile in the western part of the area and at and soil mantle, and as a result the amount of angularity an average rate of about 125 feet per mile in the east­ is not measureable. In the 2 miles between Beuchler ern part. The Devonian rocks of the area were shortened fault and Swatara Creek Gap, however, the uncon­ about 30 percent during the Acadian and Appalachian formity cuts out about 400 feet of the Cherry Ridge orogenies; thus, the Cherry Ridge thickened north­ Member which indicates an angularity of about 2°. westward before deformation at about 50 feet per mile The Cherry Ridge Member has been measured at two in the western part of the area and about 90 feet per localities in the area and at one locality a short distance mile in the eastern part. to the east. These localities are at Mill Creek Gap (fig. Most rocks in the Cherry Ridge Member are grayish 24, section 1), Swatara Creek Gap (fig. 24, section 2), red, pale yellowish brown, and pale red. The rest are and West Branch Gap, about 2 miles east of the area light red, light to brownish gray, light to medium dark (fig. 24, section 3). Other thicknesses have been com­ gray, light to olive gray, very pale to pale orange, gray­ puted across the belts of outcrop at many places in and ish orange, yellowish brown, yellowish gTay, grayish adjacent to the area. A map showing the thickness of yellow gray, pale to moderate olive brown., dusky yel­ the member (fig. 26) has been constructed from the low, dusky yellowish green, and dusky yellowish brown. measured sections and computed thicknesses. The The strata in the member range in thickness from Cherry Ridge is not recognized in the northern part one-eighth inch to 15 feet. The average sardstone bed is of the area because the Honesdale Sandstone Member about 3 feet thick, and the average siltstcne and shale which separates the similar rocks of the Cherry Ridge bed is about 1 foot 6 inches thick. Most bed^ are tabular, and Damascus Members wedges out. The thickness of but some are wedge shaped. Simple and planar cross- the Cherry Ridge in the subsurface, except near points beds 2 inches to 15 feet long are present in many sand­ of measurement, may be in considerable error because of stone beds. Most shale and siltstone beds ?,re structure- 76°45' yens' 40° 45' KLINGERSTOWN VALLEY VIEW TREMONT MINERSVILLE Area in which Cherry Ridge Member is not distinguishable

Line a)or|g which Honesdale Sandstone EXPLANATION Member is inferred to wedge out 7000- *0%^ -900- Isopachs Contour interval 100 feet X1200 Measured thickness, in feet .1100 Computed thickness, in feet

BERKS CO 40° SWATARA HILL 30'

FIGTJEE 26. Isopach map of the Cherry Ridge Member of the Catskill Formation. STRATIGRAPHY 53 less but some are laminated and fissile and a few are coarser grained and contain less interstitial clay thr,n do contorted. Some sandstone and conglomerate units are the red beds. The slightly coarser grain size and the graded; others are reverse graded in their upper parts. smaller quantity of clay matrix in the nonred beds The Cherry Ridge is composed of about equal probably allowed a greater circulation of fluids than amounts of shale, siltstone, and sandstone. A few beds was possible in the finer textured and clayier red beds. of conglomerate are scattered throughout the member. Thus, the color of the nonred beds may have developed The conglomerate in the Cherry Ridge is much less during diagenesis and consolidation because of the cir­ resistant to erosion than that of the underlying and culation of oxygen-poor water which reduced the ferric overlying members. Some pebbles reach a maximum iron to ferrous iron. If such circulation occurred, re­ diameter of 1 inch, but most are about a quarter of an ducing conditions prevailed in the coarser grained rocks inch in diameter. They are composed mostly of milky and nonreducing conditions in the finer grained onQ-s. and gray vein quartz with some milky, gray, and vari­ The only fossils of the Cherry Ridge are fragmentary colored quartzite; gray, brown, and black chert; and fossil plants that have not been studied at present. varicolored schist, phyllite, and slate. The matrices are Within the area the member seems to be late Late De­ principally medium to coarse grained, but they range vonian in age, as determined from stratigraphic position from fine to very coarse grained. and from a correlation by Willard (1939a, p. 287), who The sandstone is very fine to very coarse grained stated that this unit correlates with the Conewango of and averages fine to medium grained. Most siltstone is western Potter and McKean Counties. sandy, and the shale is chiefly silty. The Cherry Ridge Member of the southern part of The mineral assemblages of the rocks of the member the area is correlative with the upper part of the Bud- are similar and closely resemble those of the Honesdale, dys Run Member of the northern part. except for a general decrease in grain size. These rocks, BUDDYS BUN MEMBER regardless of grain size, are compositionally allied with the graywacke, subgraywacke, and protoquartzite clans. The Buddys Run Member of the Catskill Formation Most of the sandstone and conglomerate is subgray­ was named by Arndt, Wood, and Trexler (1962, p. C35) wacke, and the finer elastics are largely protoquartzite. for a small creek in the southern part of Shamokin Common quartz, vein quartz, and quartzite are the quadrangle, Northumberland County. It includes the principal mineral grains. Other common grains are strata lying between the Irish Valley and Spechty F"opf chert, ilmenite, magnetite, leucoxene, muscovite, and Members. fragments of schist, phyllite, and slate. All rock types The Buddys Run crops out on the flanks anc1 the contain considerable percentages of sericite and uni­ crest of the Broad Mountain anticlinorium in the Kling- dentified clay minerals and small percentages of tour­ erstown, Valley View, and Tremont quadrangles (GQ- maline and zircon. Sorting in the coarser elastics is 692, 699, 700). The lower part of the member commonly poor to fair; rounding ranges from angular to well- underlies a subdued rolling upland that has 100 to 250 rounded and averages subangular. Many of the larger feet of relief. The upland is characterized by a trellis quartz grains have been deeply sutured by pressure drainage pattern consisting of valleys that are eroded solution. Most smaller quartz grains are not deeply parallel and perpendicular to the strike of the outcrop belt. The upper part underlies gentle to steep, little dis­ sutured because they are surrounded by a protective matrix of clay, hematite, and sericitic material. Cement­ sected slopes that rise above the rolling upland to near the crests of Line and Mahantango Mountains. ing media in all rock types are silica, hematite, and clay. The contact of the Buddys Run with the underlying Many of the red beds contain 5 to 15 percent hematite. Irish Valley Member is in the upper part of an inter- Sedimentary structures and plant fossils suggest that tonguing sequence of red beds and gray and olive beds. the rocks of the Cherry Ridge were deposited on a It is at the base of the main red-bed sequence of the flood plain lying west and northwest of the highland Catskill Formation and above gray and olive beds of area known as Acadia. The generally fine-grained char­ the Irish Valley that replace the red beds downward. acter of these rocks indicates that Acadia was low lying The scale of intertonguing is so great that it can be during most, if not all, of their deposition, but the scat­ shown on 1: 24,000 maps. tered conglomerate beds may indicate either slight re­ The upper contact of the Buddys Run with the Spe­ juvenations of Acadia or climatic changes. chty Kopf Member is nowhere well exposed but i^ be­ The mineral assemblages of the nonred and red beds lieved to be comfomiable. Where observed, it is grad- of the Cherry Ridge are similar, except for variations ational and is placed where gray and olive beds of the in ferric versus ferrous iron content and differing per­ Spechty Kopf predominate over underlying red beds centages of clay matrix. Most of the nonred beds are of the Buddys Run. GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA

The member is not completely exposed at any place in The beds are ^4 inch to 15 feet thick and average the area. Thickness variations, therefore, must be de­ about 3 feet. Most strata are tabular bedded; wedge- termined entirely from, computations based upon struc­ shapped beds, however, are relatively common. Simple tural attitudes and the width of the outcrop. Figure 27, and planar crossbeds 2 inches to 5 feet long are com­ an isopath map of the member, was constructed from mon in the upper part of the member but are rare in the many thicknesses computed in and adjacent to the area. lower. Many shale and siltstone units are internally The Buddys Run is not recognized south of a north­ contorted, some because of structural adjustments and eastward-trending line that is the approximate north­ others because of slumping during deposition. west limit of the Honesdale Sandstone Member. South Plant fragments, raindrop impressions and mud of this line, strata correlative with the Buddys Run are cracks are preserved in many of the finer gnined rocks, divided into the Damascus, Honesdale Sandstone, and as are ripple marks, most of whose crests strike north­ Cherry Ridge Members. eastward. The Buddys Run ranges in thickness from 4,200± to Sandstone is present throughout the Buddys Run. It ±,800 ± feet. The member is thickest in the western part ranges from very fine grained to very coarse grained, of the Lykens and Klingerstown quadrangles and thins but is chiefly fine to medium grained. Thin conglomerate northeastward at an average rate of about 40 feet per and conglomeratic sandstone beds are present locally mile. Deformation shortened the Devonian rocks of the in the middle and upper parts of the member. The sand­ northern part of the area about 15 percent. Before de­ stone and conglomerate is largely subgraywacke, but formation the member thinned northeastward at an protoquartzite and graywacke are relatively common. average rate of about 34 feet per mile. The mineral constituents of these three rock types differ Fresh and weathered rocks of the member are pre­ only in the comparative percentage of quartz to other dominantly grayish red, pale red, and pale brown, constituents. They consist of vein and common quartz, many being grayish pink, light olive to olive gray, muscovite, chlorite, biotite, tourmaline, zircon, ilrnenite, dusky yellow, and pale yellowish brown. A few are leucoxene, plagioclase, orthoclase, sericite, unidentified light to dark brownish gray, dark yellowish brown, clay minerals, and rock fragments of quartzite, chert, greenish gray to dark greenish gray, light to medium shale, slate, schist., and phyllite. Pebbles in the con­ gray, greenish yellow, moderate yellow, pale orange, and glomerate are composed largely of white ar d gray vein dusky yellowish brown. quartz, quartzite, schist, phyllite, and slate.

76°45' 76° 15' 40° 45' KLINGERSTOWN \A MINERSVILLE

EXPLANATION

4500- -4600- Line along which Honesdale Sandstone Member is inferred to wedge out I^opachs Contour interval 100 feet .4300 Computed thickness, in feet

Buddys Run Member not differentiated in this area

-~~ ~ BERKS CO 40° LYKENS TOWER CITY PINE SWATARA HILL 30' 10 MILES

FIUUEB 27. Isopach map of the Buddys Run Member of the Catskill Formation. STRATIGRAPHY 55 The matrices and cement of the nonred sandstone and underlying Buddys Run or Cherry Ridge Member is conglomerate consist largely of silica, unidentified clay not well exposed in the area but is believed to be con­ minerals, and sericite, whereas in the red sandstone they formable. Where exposed, it is gradational and is ar­ are composed of these minerals and hematite and bitrarily placed where gray and olive beds of the limonite. Sorting- ranges from fair to good in proto- Spechty Kopf predominate over red beds of the.two quartzite but is chiefly poor to fair in subgraywacke and lower members. gray wacke. Although most quartz grains are subangular The contact between the Spechty Kopf and the over­ to subround, angular grains are common. lying Pocono Formation is an angular unconformity The siltstone and shale of the Buddys Run is com- (Trexler and others, 1961). The greatest observed positionally similar to the sandstone and conglomerate, angularity between these units is about 75° in Rattling differing only by increased percentages of clay and mica Creek canyon south of Lykens (GQ-701). In localities minerals. where angular relations are not well developed, or wl Q,re Most of the lower 1,000 to 2,000 feet of the Buddys red beds of the Spechty Kopf are absent or covered, Run accumulated in subaerial environments but several geologists have commonly assigned all or part of the thin marine tongues record transgressions of the sea. The, member to the Pocono. rest of the member was deposited on flood plains. The Spechty Kopf is poorly exposed at most localities The depositional environments of the Damascus, in the area; therefore, data concerning its thickness and Honesdale, and Cherry Ridge Members, which are cor­ lithology have 'been obtained from isolated outcrops and relative with the Buddys Run Member, have already by computing thicknesses at many places across the belts been discussed extensively in this report. Sediments of of outcrop. It is moderately well exposed in the area at the Buddys Run are believed to have accumulated under Mill Creek Gap (fig. 24, section 1) in Second Mountain conditions similar to those described and postulated for and east of the area at West Branch Gap (fig. 24, sec­ these members. tion 3). The fossils of the Buddys Run have not been studied, Figure 28 is an isopach map of the Spechty Kopf in but the stratigraphic position of the member indicates the area as compiled from the measurements at I Till that it is probably middle Late and late Late Devonian Creek and West Branch Gaps and from many com­ in age. The basal beds of the member tongue into the puted thicknesses. The member is absent in the south­ upper beds of the Irish Valley in the area and the mem­ eastern part of the area, may have been absent before ber as a whole is correlative with the Damascus, Hones- modern erosion on the crest of Broad Mountain in the dale, and Cherry Ridge Members of the southern part northwestern part, and reaches a thickness of about 2,400 of the area. feet in the southwestern part. SPECHTY KOPF MEMBER Rocks in the lower part of the Spechty Kopf are p^m- The Upper Devonian and Lower Mississippian cipally yellowish gray, brownish gray, and olive g~ay. Spechty Kopf Member of the Catskill Formation was In contrast, rocks in the upper part are chiefly grayish red and medium light gray to light olive gray. A few named by Trexler, Wood, and Amdt (1962, p. C36-37) are light red, moderate red, pale yellowish brown, and for a hill in the Lykens 7%-minute quadrangle of pale brown throughout the member. Dauphin County (GQ-701). It includes the strata lying Most of the gray and olive rocks of the Spechty Kopf between the Cherry Ridge or Buddys Run Member and are wedge bedded and cross stratified, and the red lNQ,ds the Pocono Formation. are chiefly tabular bedded. Beds are % inch to 15 feet The Spechty Kopf crops out on the slopes and crests thick; the gray and olive beds average about 3 feet of Line and Mahantango Mountains in the Klingers- thick and the red beds, slightly less than 2 feet. Simple town, Valley View, and Tremont quadrangles (GQ- and planar crossbeds as much as 5 feet long are common. 692, 699, 700) on Broad and Peters Mountains in the southern part of the Lykens quadrangle (GQ-701) and The Spechty Kopf is composed of sandstone, silt- west of the Beuchler fault on Second Mountain in the stone, shale, conglomerate, and coal in decreasing order Pine Grove and Tower City quadrangles (GQ-691, of abundance. Sandstone and conglomerate predomi­ 698). The upper part of the member also is exposed in nate in the lower part, of the member and siltstone and the canyon of Rattling Creek in the central part of the sandstone in the upper part. Lykens quadrangle (GQ-701). The conglomerate is composed largely of gray, milky, The member underlies a gentle to steep terrain on and light-olive-gray vein quartz pebbles and cobbles Broad and Peters Mountains. Elsewhere, it underlies that commonly are eratically distributed in an dive rough, steep, and talus-littered slopes. matrix. The gray and olive sandstone and the matrix The lower contact of the Spechty Kopf with the of the conglomerate are mainly medium to course 56 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA 76° 15'

EXPLANATION -75O- -IOOO- -I5OO- Iscpachs Contour interval 250 and 500 feet X155 Measured tt ickness, in feet ,350 Computed thickness, in feet

BERKS CO SWATARA HILL

FIGURE 28. Isopach map of the Spechty Kopf Member of the Gatskill Formation (shaded where absent). grained, some being very fine to very coarse grained. downstream from piedmonts of Acadia. In contrast, the Although most of the red sandstone is fine to medium finer grained sandstone, siltstone, and shale hi the mid­ grained, much is very fine grained. dle part of the member suggest that the source either Regardless of their grain size and regardless of was lower or farther away during their deposition. whether they are gray and olive or red, the rocks of At the end of Spechty Kopf deposition the effects of the Spechty Kopf, in decreasing order of abundance, the third episode of the Acadian orogeny were felt far­ are subgraywacke, protoquartzite, and graywacke. The ther to the northwest and deformed the rocks of the principal mineral constituents of all rock types are area. Subsequently, the rocks of the membe^ were com­ grains of vein and common quartz with subordinate pletely removed by erosion in some places, £-,nd then the amounts of biotite, muscovite, sericite, chlorite, unidenti­ area was covered by the basal sediments of the Beckville fied clay minerals, plagioclase, orthoclase, leucoxene, Member of the Pocono Formation. ilmenite, zircon, and tourmaline, and rock fragments of The rocks of the Spechty Kopf are believed to have quartzite, schist, phyllite, chert, slate, and shale. The accumulated on a flood plain in environments similar grains are subangular to subround in the protoquartzite to those described for the upper parts of the Damascus and angular to subangular in the subgraywacke and and Buddys Run Members and for the Honesdale Sand­ graywacke. Sorting is poor to fair in the protoquartz­ stone Member and Cherry Ridge Member. ite and poor in the subgraywacke and graywacke. The Spechty Kopf Member is of Late Devonian and Cementing materials in the gray and olive rocks are Early Mississippian age. This assignment is based in silica, unidentified clay minerals, and sericite; but in the part on plant fossils and in part on stratigraphic posi­ red beds they are chiefly limonite, hematite, and clay. tion. The assemblage of plant fossils from a coal bed The sediments of the Spechty Kopf were eroded from on Line Mountain and from another on Berry Mountain an ancient highland that lay southeast and east of the contain Adiantltes spp. (S. H. Mamay, onl commun., area. These sediments are the sedimentary record of 1960), which is indicative of an Early Mississippian the second uplifting of Acadia during the Acadian age (Read, 1955, p. 8). The stratigraphic portion of the orogeny. Spechty Kopf between the Lower Mississippian Pocono The coarse sandstone and conglomerate in the basal Formation and the Upper Devonian Cherry Ridge or and upper parts of the Spechty Kopf suggest that these Buddys Run Member of the Catskill Formation sub­ parts of the member were deposited a short distance stantiates the age determined from the fossil plants. STRATIGRAPHY 57 Correlation of the Spechty Kopf with other strati- 28 and 29. During the orogeny, the rocks of the area graphic units in Pennsylvania is difficult because Upper were folded into several northeastward-trending anti­ Devonian and Lower Mississippian rocks are rather clines and synclines that were subsequently beveled by unfossiliferous, because the pre-Pocono unconformity the pre-Pocono erosion surface. The geographic posi­ has not, as yet, been completely delineated, and 'because tions of these ancient folds are approximately deline­ rocks of this age have not been studied adequately in ated in figure 28 by the northeastward-trending thin most areas. The member may be partly or wholly cor­ to thick belts of the Spechty Kopf Member. A compari­ relative with the Elk Mountain Sandstone and Mount son of figures 28 and 29 also indicates that these folds Pleasant Red Shale of Willard (1939a, p. 282-283) of are partly recorded by thickness variations of the entire eastern and northern Pennsylvania, with the marine Catskill Formation. Oswayo Formation of north-central Pennsylvania, and with the Pocono-Catskill Transition Group of I. C. PRE-POCONO UNCONFORMITY White (1883, p. 49-52) of northeastern Pennsylvania. For many years, geologists have speculated whether The lower part of the Pocono Formation in central and the Acadian orogeny extended into eastern Pennsyl­ eastern Pennsylvania, as recognized in many published vania. Since the latter part oi; the 19th century there reports, may contain rocks that would be assigned to has been little detailed geologic mapping that could be the Spechty Kopf by the authors. used to solve this problem. C. D. White (1934) and THICKNESS OF THE CATSKILL FORMATION Willard (1936, p. 599-600) believed that a disconform- ity separated the Pocono and Catskill Formations. It The Catskill Formation ranges in thickness from may be deduced from the outcrop patterns on Willard's 5,100 feet in the southeastern part of the area to 9,400± geologic map (fig. 72) and from the text of his report feet in the southwestern part (fig. 29); the latter thick­ that the region northeast of the report area was tilted ness is the greatest recorded for Catskill rocks in down to the northwest and then eroded before the depo­ Pennsylvania. sition of the Pocono Formation. In 1961, Trexler, Wocd, The effects of the Acadian orogeny and pre-Pocono and Arndt described the unconformity in the area and erosion on the thickness of the Catskill are determinable the surrounding region. by comparing figure 30, a map showing the thickness of The unconformity between the Spechty Kopf Mem­ the pre-Spechty Kopf rocks of the Catskill, with figures ber of the Catskill and the Pocono Formation is best

76°45' 76°

EXPLANATION -7500- -8000- Isopachs Contour interval 500feet X 5110 Measured thickness, in feet .5650 Computed thickness, in feet

BERKS CO SWATARA HILL

FIGURE 29. Isopach map of the Catskill Formation. 58 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA 76°15'

KLINGERSTOWNK

6500 6600

EXPLANATION 5500

Isopachs Contour interval 100feet

X 5110 Measured thickness, in feet .6500 Computed thickness, in feet

BERKS CO SWATARA HILL

FIGURE 30. Isopach map of members of the Catsklll Formation older than the Spechty Kopf Member. preserved on Broad and Peters Mountains in the south­ Pocono by an erosion surface. The Spechty Kopf may ern part of the Lykens quadrangle (GQ-701). There, have been completely removed by erosion between these the upper 2,000 to 2,300 feet of the member is truncated mountains near the axis of the present Broad Mountain by an erosion surface. Beds of the Spechty Kopf dip 10° anticlinorium (fig. 28). to 30° more steeply northward on the north limb of the Pre-Pocono erosion also removed the Spechty Kopf Joliet anticline than do overlying beds of the Pocono, Member from Second Mountain between a point a few and they dip as much as 25° less steeply southeastward hundred feet west of the Beuchler fault in the Pine on the south limb. These angular relations indicate that Grove quadrangle and the east border of the Swatara the Spechty Kopf locally was folded or tilted about 30° Hill quadrangle (GQ-689, 691). In the ar^a, where the northward and northwestward and, subsequently, Spechty Kopf is removed, the Pocono rests unconform- eroded before accumulation of the Pocono. ably upon beds of the Cherry Ridge Member of the The angularity between bedding planes of the Catskill Formation at a divergent angle of about 2°. Spechty Kopf and the Pocono is as great as 75° in Rattling Creek canyon about 1 mile south of Lykens MISSISSIPPIAN SYSTEM (GQ-701). Structural attitudes of Spechty Kopf rocks Mississippian rocks range in thicknesr from about on Berry, Broad, and Peters Mountains indicate that 5,000 feet on the Broad Mountain anticlinorium to the rocks were folded into a broad open syncline during about 8,500 feet in the Minersville synclinormm. the Acadian orogeny. Subsequently, during the Appa­ Much of the Spechty Kopf Member of the Catskill lachian orogeny, the broad open syncline was further Formation is of Early Mississippian age. This member folded and became the Joliet anticline, the Battling is described in the chapter on Devonian and Mississip­ Creek syncline, and the Berry Mountain anticline pian rocks. It is overlain unconf ormably by the Pocono (Trexler and others, 1961, fig. 38.2). Formation, which is divided, in ascendirg order, into Detailed mapping on Line and Mahantango Moun­ the Beckville and Mount Carbon Members. The Mauch tains in the Klingerstown, Valley View, and Tremont Chunk Formation of Late Mississippian and Early quadrangles (GQ-692, 699, 700) has shown that the Pennsylvanian age rests conformably on the Mount Sprechty Kopf Member varies greatly in thickness in Carbon Member and is divided into three informal very short distances and that it is separated from the members. STRATIGRAPHY 59 POCONO FORMATION West Branch Gap in Second Mountain. This gap is In 1876, Lesley (p. 221-227), in his description of the several miles east of the report area. Boyd's Hill well at , introduced the name The member is poorly to moderately well exposed at Pocono Sandstone for the sequence of gray sandstone Mill Creek and Swatara Creek Gaps in Second MOMII- and conglomerate that lies between the red beds of the tain (GQ^691), is moderately well exposed at Battling Mauch Chunk and Catskill Formations. The succeeding Creek Gap in Berry Mountain (GQ-701), and is largely year, Franklin Platt and W. G. Platt (1877, p. XXVI), covered at Pine Creek Gap in Mahantango Mountain in describing the new formations proposed by Lesley, (GQ-700). It underlies Second, Peters, Broad, Berry, stated that the gray sandstone and conglomerate be­ Mahantango, and Line Mountains (GQ-689, 690, 691, tween the Mauch Chunk and Catskill on the Pocono 692, 698, 699, 700, 701). The Beckville commonly crops Plateau "should be called the Pocono Formation, for it out on the crests of ridges. The slopes beneath these forms the mass of the great mountain plateau between crests are generally rough and steep and are character­ the Delaware and Lehigh Kivers." ized by a series of subdued cliffs, cuestas, and hog­ A few years later I. C. White (1882) proved that backs. In those localities where the crests are underlain most of the Pocono Plateau was surfaced by the Cats- by either the Spechty Kopf or Mount Carbon MemHr, kill Formation. He (1883, p. 49) recommended that his the outcrop belt of the Beckville is largely covered by Mount Pleasant Conglomerate and 300 to 500 feet of talus from those members. overlying red rock be reassigned to his Pocono-Catskill The Beckville unconformably overlies the Spechty Transition Group. Lesley (in Lesley and others, 1892- Kopf and Cherry Eidge Members of the Catskill For­ 95, p. XV) in his redefinition of the Pocono, ignored mation. The unconformity is beneath a widespread White's recommendation by stating: "Therefore, to find basal conglomerate. East of the Beuchler fault on Sec­ any Pocono on the Pocono Plateau, one must go a num­ ond Mountain, the Beckville overlies the Cherry Ridge, ber of miles to the north of the front edge of the plateau, but elsewhere it rests on the Spechty Kopf. At most where ridges of the lowest Pocono rock, the Mount localities the basal conglomerate rests on red beds, but Pleasant Conglomerate, remain imeroded." Willard at a few places it overlies gray and olive conglomerate (1936, p. 597-598) accepted White's recommendation by and sandstone. The position of the unconformity in removing White's Mount Pleasant Conglomerate and these latter places can only be established with certainty the overlying red beds from the Pocono and assigning by careful lateral tracing, and in a few localities, by them to the Catskill Formation. He, however, accepted angular discordance between underlying and overlying Lesley's definition of a type area. beds. The Pocono is classified as a formation by the U.S. The upper contact of the Beckville is placed at the Geological Survey. It includes the rocks between the bottom of the basal conglomerate of the Mount Carbon underlying Catskill Formation and the overlying Member. At most places in the area the upper part of Mauch Chunk Formation as defined by White and Wil­ the Beckville is sandstone, shale, siltstone, and ccal; lard. The base of the formation in the area is the pre- therefore, the contact between the finer grained elastics Pocono unconformity, and the top is the lowest red bed of the Beckville and the basal conglomerate of the of the Mauch Chunk. The formation, in ascending Mount Carbon generally is easy to locate. Near the order, consists of the Beckville and Mount Carbon northwest corner of the area, however, the basal con­ Members in the report area. glomerate grades westward into very coarse sandstone, The Pocono is the principal ridge former of the area, and the position of the contact becomes hard to deter­ underlying from north to south: Line, Mahantango, mine. For this reason, it is not advocated that the Pocono Berry, Broad, Peters, and Second Mountains. It gen­ be divided into members to the north and west of the erally crops out on narrow and precipitous ridge crests, area. except on Broad Mountain, in the area where Line and Sections of the Beckville were measured at Mill Cr^ek Mahantango Mountains join, and in the area where Gap (fig. 31, section 1) ; Swatara Creek Gap (fig. 31, Peters and Broad Mountains join. Dip slopes of the sect.ion 2); West Branch Gap (fig. 31, section 3), which formation on these mountains are eroded either into lies several miles east of the area; and Schuykill Gap subdued and poorly exposed cuestas and hogbacks or (fig. 31, section 4), which is a short distance farther are covered by large talus fields. east. Figure 32 is an isopach map of the Beckville Mem­ BECKVILLE MEMBER ber. It was compiled from thicknesses at these sections The Beckville Member was established by Trexler, and from thicknesses calculated across the outcrop bolts Wood, and Arndt in 1962 (p. C38). It was named for in and adjacent to the area. The member is thickest on a village a short distance south of the type section at Broad and Peters Mountains and is thinnest in the s^ib- 316-352 O <69 5 60 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA

EXPLANATION 1 Swatara Creek Gap, Mill Creek Gap, Second Mountain, Second Mountain, Lebanon County Schuylkill County West Branch Gap, Schuylkill Gap, Second Mountain, Second Mountain, °0 Schuylkill County Schuylkill County

Mount Member

FEET 0

Covered interval O o. O 0 TT 1104 Total thickness, in feet

Unconformity

37' TT1127 30" TT 1180 TT 1242

40° 30' 0 5 MILES I . , . . I INDEX SHOWING LOCATION OF SECTIONS

FIGURE 31. Columnar sections of the Pocono Formation. surface of the central and northern parts. The thickness centrated in lower part, and sandstone predominates trends of the member approximate those of the under­ in the upper part. lying Spechty Kopf Member (fig. 29), which suggests The conglomerate is in beds 1 foot to 25 feet thick, but that the Acadian orogeny lasted into Beckville time. most beds average about 4 feet. The average bedding unit Freshly exposed rocks of the member are mainly very is cross stratified and wedge shaped; the res4^ are tabular light to medium gray, some being pale to olive gray, and lenticular. Simple and planar cross-strata range dark gray, greenish gray, brownish gray, yellowish gray, from small to as long as 20 feet. pale red, pale to dark yellowish orange, and grayish The basal conglomerate is persistent throughout the pink. Weathered rocks are commonly similar in color, area, is more extensive than any other conglomerate, and but a few 'are moderate reddish orange, dark greenish may be correlative with the Griswold Gap Conglomerate gray, light brownish gray, olive black, and light brown. of I. C.White (1881, p. 56-57) of northeastern Pennsyl­ The Beckville is composed of conglomerate, sandstone, vania. Pebbles and cobbles in this and oth?-r conglom­ siltstone, shale, and coal. Conglomerate is largely con­ erates range in diameter from 14 inch to 4 inches. Those STRATIGRAPHY 61 76°45' 76°15' 40° 45' _^_KLINGERSTOWN VALLEY VIEW TREMONT MINERSVILLE 400 .350 .350 300 .350 -300-

EXPLANATION 500 *°sfi^° 600 Isopachs Contour interval 100 fee' X454 Measured thickness, in feet .430 Computed thickness, in feet

"" BERKS CO 40° SWATARA HILL 30'

FIGURE 32. Isopach map of the Beckville Member of the Poeono Formation. of vein quartz and quartzite are commonly equidimen- wacke clans. Regardless of differences in grain size, the sional to ovoid, are less commonly elongate, and are mineral assemblages of these rocks are similar and vpry chiefly rounded to well rounded. The few clasts of other only in the proportion of quartz to rock fragments, mica rock types generally are elongate and flattened. The minerals, and unidentified clay minerals. long axis of most of the elongate and ovoid clasts are The pebbles and cobbles in the conglomerate consist oriented parallel to bedding. of milky, white, light-gray, and medium-gray vein The sandstone beds of the Beckville range in thick­ quartz; light- to dark-gray, brownish-gray, pale-nd- ness from 1 foot to about 10 feet and average about 3 purple, and medium-bluish-gray quartzite; and dark feet. Most are tabular and cross stratified; the rest are varihued sandstone, siltstone, schist, gneiss, slate, p.nd wedge shaped and parallel stratified. Abundant simple chert. Most of these clasts are well lithified and rounded and planar cross-strata are mostly less than 5 feet long, to varying degree. Poorly lithified angular shale chips but some are as long as 25 feet. and clay galls are present in the basal parts of mr.ny The siltstone is mainly in beds about 3 feet thick, but conglomerate and sandstone beds. 14-inch to 10-foot beds are common. The thicker beds The siltstone, sandstone, and the matrices of the con­ are concentrated largely in the lower part of the member glomerate consist of detrital grains of vein and common where thin beds of fine-grained sandstone and shale are quartz; fragments of quartzite, sandstone, schist, slate, intercalated at many places. Much of the siltstone con­ phyllite, and chert; varying amounts of chlorite, bio- tains scattered fine to medium grains of well-rounded quartz. tite, muscovite, and sericite; and small amounts of l

MOUNT CARBON MEMBER difference in erosional resistance between the competent rocks of the Mount Carbon and the less resistant rocks Trexler, Wood, and Arndt (1962, p. C39) named the of the Mauch Chunk. Mount Carbon Member of the Pocono Formation for a Sections of the Mount Carbon were measured at Mill village that lies about 2.5 miles east of the area. Creek Gap (fig. 31, section 1) and Swatarr, Creek Gap The member generally crops out in dip slopes on Sec­ (fig. 31, section 2) in the Pine Grove quadrangle (GQ- ond, Peters, Broad, Berry, Mahantango, and Line 691). Two other sections were measured east of the Mountains, but locally, it underlies the crests (GQ- area at West Branch Gap (fig. 31, section 3) and Schuyl- 689, 690,691,692,698,699, TOO, 701). On Second, Mahan­ kill Gap (fig. 31, section 4).

76°15'

400*KLINGER£TOWN\ .,..A/ALLEY VIEW ^^ ^- ^-^650 ^ »-7cn

EXPLANATION

500 -600- I^opachs Contour interval 100 feet X738 Measured thickness, in feet .750 Computed thickness, in feet

BERKS CO SWATARA HILL

FIGURE 33. Isopach map of the Mount Carbon Member of the Pocono Formation. STRATIGRAPHY 63 The thickness of the member is illustrated in figure been deeply sutured by pressure solution, many seem to 33. It is thickest in the southwestern part of the area, have been rounded to well rounded before suturing. All where it exceeds 1,000 feet, and is thinnest in the north­ rock fragments except chert, and quartzite are character­ western part, where it is slightly less than 400 feet thick. istically elongate and range from angular to well The thickness trends of the Mount Carbon approximate rounded. Most chert grains are rounded. Many schist, those of the underlying Beckville Member (fig. 32), the shale, and phyllite fragments seem to have been crushed Spechty Kopf Member of the Catskill Formation (fig. and to have flowed into interstitial pore space. The mat­ 28), and the Catskill Formation (fig. 29), which, sug­ rices of much of the subgraywacke and protoquartzite gests that folding as a result of the Acadian orogeny are composed of these crushed fragments, bent biotite was still affecting the area slightly. and muscovite plates, small fragments of quartz, sf-i- Fresh, rocks of the member are chiefly light to dark cite, and unidentified clay minerals. Cementing min­ gray, light to olive gray, and light to dark greenish erals in these rocks are silica, clay, sericite, crushed gray; a few are light bluish gray, light to brownish rock fragments, and silt-sized quartz grains. The prin­ gray, pale to moderate yellowish brown, very pale to cipal cement in the orthoquartz:te is silica. grayish orange, grayish pink, grayish orange pink, Sorting in the subgraywacke is poor to fair, in the grayish olive, dusky yellow, greenish black, and black. protoquartzite it is poor to moderate, and in the ortho- Weathered rocks are principally light to dark gray and quartzite it is moderate to good. Most of the sandstone light to olive gray. Other weathered rocks are the same is medium grained, but very fine grained, fine-grained, color as the fresh rock, and are also dark yellowish coarse-grained, and very coarse grained sandstone is brown, moderate olive brown, brownish black, olive common. black, yellowish gray, and moderate yellow green. THICKNESS OF THE POCONO FORMATION Individual beds are 2 inches to 40 feet thick and aver­ age about 3 feet. Wedge-shaped and lenticular beds are Figure 34 is an isopach map of the Pocono Forma­ common, but most are tabular. Many sandstone and tion constructed from thickness data in and adjacent to conglomerate beds exhibit simple and planar cross-strat­ the report area. The formation is thinnest in the north­ ification of 2 inches to 25 feet. western part, where it is probably less than 700 feet, and The member consists, in decreasing order of abun­ is thickest in the southwestern part, where it exceeds dance, of sandstone, conglomeratic sandstone, conglom­ 1,700 feet. The area of greatest thickness coincides partly erate, siltstone, shale, and coal. with the area of greatest thickness of the Spechty Kopf The conglomerate is composed of pebbles and cobbles Member and the Catskill Formation. This approximate of milky, white, and gray vein quartz and varicolored superposition suggests that the Acadian disturbance quartzite, schist, slate, shale, and sandstone. These clasts continued during deposition of the Pocono. are set in a matrix of very fine to very coarse sand. Most DEPOSITION OF THE POCONO FORMATION vein quartz and quartzite clasts are equidimensional to ovoid and rounded to well rounded; and those composed Pocono rocks seem to have accumulated principally of other rock types are chiefly elongate. as flood-plain deposits, to a lesser extent as swamp de­ Much of the siltstone and shale is arenaceous and posits, and perhaps locally, as lacustrine deposits. Tli^y contains thin intercalated beds of very fine grained and were deposited in an asymmetric northeastward-trend­ fine-grained sandstone. Abundant plant fossils and thin ing basin whose axis lay close to its southeastern margin lenses of coal are common in some shale beds. and the source area. The sediment that formed these Regardless of grain size, the rocks of the Mount rocks was eroded from a mountainous region southeast Carbon Member are compositionally allied to the ort-ho- of the report area that was uplifted during the final quartzite, protoquartzite, and subgraywacke clans. The phase of the Late Devonian and Early Mississippi an mineral assemblages of these rock types are similar and Acadian orogeny. differ only as to the percentage of specific minerals. The Sedimentation began when coarse elastics eroded from principal constituents are grains of vein and common the mountainous region were distributed by stream? as quartz and fragments of quartzite. Accessory constitu­ broad sheets upon the pre-Pocono erosion surface. As ents are fragments of schist, slate, phyllite, and chert; fluvial deposition continued, the mountain area was up­ plates of chlorite, biotite, muscovite, and sericite; grains lifted slightly from time to time. Near the middle of of leucoxene, ilmenite, magnetite, sphene, tourmaline, Pocono deposition the source was strongly rejuvenated, and zircon; traces of altered and unaltered andesine; and the basal conglomerate of the Mount Carbon Mem­ and films of hematite and limonite. Even though the ber was deposited. During the remainder of Pocono margins of most grains of quartz and quartzite have time, the source area was eroded so that by the begin- 64 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA

EXPLANATION -1500- -1600- Isopaehs Contour interval 100feet

X1180 Measured thickness, in feet .1350 Computed thickness, in feet

BERKS CO SWATARA HILL

FIGURE 34. Isopach map of the Pocono Formation. ning of Mauch Chunk sedimentation it no longer con­ values for crustal shortening that were calculated by tributed coarse detritus. Cloos (1940, p. 847). According to Pelletier (1958, p. Thin lenticular coal beds, formed from the plant re­ 1056), 6-inch cobbles were probably the iraximum size mains preserved in local swamps, are present at places. transported at those points where Pocono streams Because these coal beds are thin and lenticular, it seems crossed the fall line into the basin of deposition. likely that they were deposited in small shallow swamps. Structural analyses made by the authors indicate that The coal beds and the gray color of the rocks of the the amount of crustal shortening of Lower Mississip- Pocono indicate that reducing conditions prevailed dur­ pian rocks in the report, area was about 25 percent, or ing accumulation, which contrasts strongly with the 13 percent greater than the average calculated by Cloos. general oxidizing conditions of Catskill and Mauch Recent structural studies in the Reading P-ong and the Chunk times. Great Valley (A. A. Drake, Jr., oral conimun., 1962) Near Taylorsville, in the Minersville quadrangle indicate that crustal shortening there was more than 50 (GQ-690), and in the northwestern part of the Kling- percent, a minimum of 10 percent greater than the value erstown quadrangle (GQ-700), the pebbles in the rocks calculated by Cloos. of the Pocono reach a maximum diameter of 2 inches Cobbles as much as 8 inches in diameter are rather and 1% inches, respectively. The maximum diameter common in the upper member of the Maucl Chunk For­ increases gradually southeastward to 3 inches on Sec­ mation on Sharp Mountain, and cobbles of similar s; ze ond Mountain (GQ-689, 690, 691, 698). are present in the Pottsville Formation in the southern Pelletier (1958, fig. 16) used the southeastward in­ part of the Southern Anthracite field. These 8-inch cob­ crease in the maximum size of clasts in the Pocono at bles certainly did not accumulate above a frll line. Their any particular locality as the principal evidence for con­ occurrence in the Late Mississippian and Pennsylvania!! cluding thait the fall line of the Pocono basin of deposi­ basin of deposition argues strongly against using 6-inch tion lay about 25 miles northwest of Atlantic City, N.J. cobbles to demarcate the Pocono fall line. TVherever ob­ The method used to determine the location of the fall served by the authors, the present-day fall line of the line was to plot a location graph transverse to the ob­ Atlantic Coastal Plain is marked by boulders that served increase in maximum pebble and cobble diam­ greatly exceed the 6-inch limitation imposed by Pel­ eter. He removed the effects of deformation bv / usinjro letier. Much more complete data than are now available STRATIGRAPHY 65 would be required to determine the average maximum extensive deposits of talus and soil, and commonly are size of these boulders. Casual observations by the au­ heavily forested. In contrast, the middle part generally thors, however, suggest that the average is between 10 underlies areas where the relief does not exceed 200 and 12 inches. If stream velocities and gradients of the feet. Rocks in this part commonly are covered by a thin Pocono source area were similar to those of the present to thick mantle of soil and talus. , the Pocono fall line would have been marked The stratigraphy of the Mauch Chunk has b^-en by boulders of similar size. studied more closely than that of any other rock unit, Assuming that boulders as much as 10 to 12 inches except the Pottsville and Llewellyn Formations. in diameter marked the Pocono fall line, and using the Despite this study, many facets of the stratigraphy are values for crustal shortening determined in the area poorly understood or unknown because of structural and those advocated by Drake to the south, the fall line complexities and the lack of stratigraphic markers in a lay about 40 to 50 miles southeast of the area. Six-inch thick monotonous red-bed sequence. In order to trace cobbles, under this supposition, were deposited about 30 structural features and to discern stratigraphic changes, miles southeast of the area. many 100- to 500-foot thick lithologic units were mapped in the Mauch Chunk. These units consist of AGE AND CORRELATION OF THE POCONO FORMATION resistant sequences of red sandstone interbedded with The Pocono Formation is of Early Mississippian age lesser amounts of red siltstone and shale, or nonresistant as determined from plant fossils (Read, 1955, p. 9-15). sequences of red siltstone and shale interbedded with It is correlative with the Price Sandstone, Big Stone lesser amounts of red sandstone. Most of the units are Gap Member of the , and Maccrady laterally persistent within a single belt of outcrop. This Shale of Virginia; with parts of the Chattanooga Shale, persistency aided greatly in the tracing of faults and Fort Payne Chert, New Providence Shale, and Maury folds, but because of soil cover at many localities, it was Formation of Alabama, , and Georgia; and not of material aid in the understanding of strati- with the Knapp Formation, , Bedford graphic changes. Shale, and Cuyahoga Group of Western Pennsylvania LOWER MEMBER and Ohio (Read, 1955; Weller and others, 1948, The lower member of the Mauch Chunk Formation chart 5). is sporadically exposed on the lower slopes of Mah

1TI ' '!' 0 ' 0 0 .0 1 1 ' 1 1 1 1 1 1 II : II '1 ' ' II- II III .-'j;: ' ° 'i ii Q ° Id 0 ' 1 ' 0. 0 ' i i j li : ' -il | ;,' ;: l ' ff ° C° : ''ii 1 1 : ' 1 II '' ' 0- ' ' !' q jj 'II- |j': 1 l'l . -'.'I'-'.' °: lo 1 1 : | . : 1 .' :.'! |: IV 1 : -.-' o. i o: ^o L ' oj^0 50 g ||;

Lower member of Middle member of Upper member of Mauch Chunk Formation Mauch Chunk Formation Mauch Chunk Formation

r-t-P 5'

72 % tt> cr? I CO TT J.'l-

CO 70 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA calcite but are otherwise similar to these calcite-bearing PENNSYLVANIAN SYSTEM rocks. Pennsylvanian rocks in the area consist of an un­ During late Mauch Chunk time, a large region east determined part of the Mauch Chunk Form ation, prob­ and southeast of the area was uplifted by the first pulsa­ ably not more than 200 feet; the Pottsville Formation, tion of the Appalachian orogeny. Abundant pebbles and 800 to 1,500 feet thick; and the Llewellyn Formation, as cobbles of vein quartz, quartzite, mica, schist, phyllite, much as 3,500 feet thick. The Pennsylvanian sequence slate, and gneiss in the upper member show that the up­ ranges in total thickness from about 4,300 to 5,000 feet. lifted region was underlain principally by low-rank The Pottsville Formation of Early and Middle metamorphic rocks. Other pebbles and cobbles of sand­ Pennsylvania!! age consists, in ascending crder, of the stone, shale, and siltstone, however, indicate that a part Tumbling Run, Schuylkill, and Sharp Mountain Mem­ was underlain by sedimentary rocks; common or igne­ bers. Each member is composed of conglomerate, con­ ous quartz fragments suggest that a small part was glomeratic sandstone, sandstone, siltstone, shale, and underlain by igneous rocks; and the presence of traces anthracite. of sillimanite indicates that high-rank metamorphic The Llewellyn Formation of uppermost Middle and rocks were locally exposed. Late Pennsylvanian age consists of sandstone, siltstone, AGE OF THE MAUCH CHUNK FORMATION and shale; numerous thin to thick beds of anthracite; and a considerable amount of conglomerate and con­ The Mauch Chunk Formation in the area is of Late glomeratic sandstone. Mississippian and Early Pennsylvanian age. The Late Mississippian age of the bulk of the unit has been known POTTSVILLE FORMATION and accepted for many years, but the Early Pennsyl­ The Pottsville was named by Lesley in 1876 (p. 221- vanian age of the upper beds was recognized only 227) in the description of the Boyd's Hill well near recently (Wood and others, 1962, p. C40-C41). Pittsburgh in western Pennsylvania. It was defined in The contact between the Mauch Chunk and the over­ this description as a conglomerate overlying the Mauch lying Pottsville Formation at the type section of the Chunk Red Shale of Lesley and underlying the Lower latter unit is also the type locality where the time bound­ Productive Coal Measures ( of ary between the Mississippian and Pennsylvanian pe­ modern usage). riods was defined (Wood, and others, 1956, p. 2670- C. D. White in 1900 (p. 755-756) ignored the existence 2671; Moore and others, 1944, p. 665). The type section of the original type section in the Boyd's Hill well and is a short distance east of the report area at Schuylkill stated that the type section of the Pottsville, as com­ Gap in Sharp Mountain on the south edge of the South­ monly recognized by previous workers, lay south of the ern Anthracite field. The upper member of the Mauch city of Pottsville in Schuylkill Gap. He measured a Chunk intertongues with the Tumbling Run Member section on the east side of the gap along the tracks of the of the Pottsville, and the contact rises stratigraphically Pennsylvania Railroad and partitioned tin formation northward. Thus, at the type section of the Pottsville at into four paleobotanic divisions (p. 773-775). Since Schuylkill Gap, the Pennsylvanian and Mississippian 1900, White's section has been considered the type for time boundary lies at the contact between the members, the formation. Recently, a better exposed reference sec­ but in the northern part of the area, the time boundary tion was established about 150 feet east of the type sec­ lies at an indeterminate position in the upper member of tion on the eastern side of Pennsylvania Route 61 the Mauch Chunk because of the northward rise. (Wood and others, 1956, p. 2671-2673). The Mauch Chunk correlates not only with the lower The Pottsville has been classified as a conglomerate, part of the Pottsville Formation but also with many a sandstone, a formation, a group, and a series. In the other Upper Mississippian and Lower Pennsylvanian Anthracite region, the U.S. Geological Surrey classifies units. It is correlative with parts or all of the Green- it as a formation, which is divisible at many places into brier Limestone of western Pennsylvania, Maryland, the Tumbling Run, Schuylkill, and Sharp Mountain Virginia, and West Virginia; with the Bluefield Shale, Members. , Formation, and Prince- TUMBLING RUN MEMBER ton Sandstone of West Virginia; with the Glen Dean Limestone, , and Bluestone For­ The lowest division of the Pottsville Formation in the mation of Virginia; and perhaps with the basal parts of Anthracite region was named the Tumbling Run Mem­ the Lee and Pottsville Formations of western Pennsyl­ ber in 1956 for a small stream southeast of Schuylkill vania, West Virginia, Virginia, , and Ten­ Gap (Wood and others, 1956, p. 2671). It includes the nessee (Weller and others, 1948, chart 5). Lower Lykens Division and the lower part of the Lower STRATIGRAPHY 71 Intermediate Division of C. D. White (1900, p. 773- conglomerate of the Schuylkill Member are more abun­ 775). dant, are evenly distributed in a sandstone matrix, are The Tumbling Eun Member crops out on the slopes as much as 3 inches in diameter, are not fractured, and and crests of Bear, Big Lick, Broad, Coal, Little, are generally well rounded. They are composed prin­ Mahanoy, Sharp, Sherman, Short, and Stony Moun­ cipally of vein quartz 'and quartzite. tains (GrQ-689, 690, 691, 692, 698, 699, 701). Slopes un­ It is difficult to determine the thickness of the Tum­ derlain by the members are commonly steep and rough bling Run Member at most places because of structural and are generally covered by a thick mantle of talus; in complications, a densie forest cover, and a mantle of contrast, where the member underlies the crests of the talus. Plates 1-3 show three lines of stratigraphic sec­ mountains, the surface is smooth and featureless and tions that cross the area from west to east. These lines is characterized by small relief. All belts of outcrop are illustrate the variations in lithology and thickness of overgrown with a dense scrub forest. parts or all of the Pottsville Formation and the lower The lower contact of the Tumlbling Run Member is and middle parts of the Llewellyn Formation as meas­ at the top of the uppermost red bed of the Mauch Chunk ured in boreholes, in mines, and on the surface. Twerty- Formation. The upper contact is placed at the bottom three of these stratigraphic sections were measured, of the basal pebble conglomerate of the Schuylkill Mem­ partly in beds of the Tumbling Run. ber. The rocks in the upper part of the Tumbling Eun The Tumbling Run Member ranges in thickness from arie generally finer grained than the overlying basal about 275 feet in the western and northwestern pr.rts conglomerate and are light to dark gray, olive gray, of the area to about 600 feet in the southeastern part greenish gray, grayish orange, moderate yellowish (fig. 36). It thickens irregularly to the south and south­ brown, and dusky yellow, whereas the overlying basal east, at 25 to 30 feet per mile. Structural calculations conglomerate is generally light to dark gray. Pebbles indicate that the Pennsylvania^! rocks of the area were in the upper part of the Tumbling Eun are sparse, are telescoped about 45 percent during the Appalachian scattered at random in a sandstone matrix, are as much orogeny. Before deformation the Tumbling Run thick­ as iy2 inches in diameter, commonly are fractured and ened southward and southeastward at about 14 to 17 generally are rounded. They consist of a variety of rock feet per mile. types, such as vein quartz, quartzite, chert, schist, gneiss, Fresh and weathered rocks of the member exhibit sandstone, siltstone, and shale. The clasts in the basal a considerable range in color. Conglomerate, conglom-

76° 15'

EXPLANATION

-500- -550- Isopachs Contour interval 50feet

X565 Measured thickness, in feet ,500± Computed thickness, in feet

BERKS CO SWATARA HILL

FIGURE 36. Isopach map of the Tumbling Run Member of the Pottsville Formation. 72 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA eratic sandstone, and sandstone are light to dark gray, 1% feet thick. Tabular bedding predominates over all light to olive gray, yellowish gray, dusky yellow, green­ other types, but lenticular and wedge bedding are com­ ish to dark greenish gray, grayish orange, yellowish mon. Small- to medium-scale simple and planar cross- brown, and moderate olive brown. Shale and siltstone bedding is prevalent in all bedding1 types. are medium to dark gray, light to olive gray, dusky yel­ Shale and siltstone compose about 15 percent of the low, greenish gray, and black. Tumbling Run. Many siltstone and shale beds are y2 Conglomerate and conglomeratic sandstone compose inch to 2 feet thick, the remainder being 2 to 20 feet about 55 percent of the Tumbling Run. and are concen­ thick. Most are tabular, but lenticular and wedge-shaped trated largely in the lower and middle parts. The cob­ beds are common. Although some of the shale and silt- bles and pebbles in these parts of the member have an stone is cross laminated, most is parallel laminated. average diameter of about 1 inch, but locally are as Six beds of anthracite are present in tin member in much as 8 inches in diameter. In the upper part of the the area. In ascending order, these are the Lykens Valley member, the average diameter is about y2 inch, and the Nos. 7, 6, 5,4,3%, and %% coal beds. Three of these, the maximum is about l1^ inch. Cobbles and pebbles Lykens Valley Nos. 6, 5, and 4 coal beds are persistent throughout the member are composed largely of vein and have been traced throughout the area., except for quartz and quartzite and lesser amounts of chert, schist, the easternmost part (Wood and Trexler, 1968b, c). gneiss, sandstone, shale, siltstone, slate, phyllite, and The others are less persistent and are confined to the granite. Most are subrounded to well rounded and aver­ western part of the area on the limbs of the Miners- age subrounded to rounded. ville synclinorium. On the north limb cf the north The conglomerate of the Tumbling Run generally is trough of the synclinorium, however, they are too thin poorly sorted. The cobbles and pebbles commonly are to be shown on the coal maps (Wood p,nd Trexler, scattered in the matrix and exhibit no apparent linea- 1968b). The lowermost of the less persistent beds, the tion, other than the more ovoid ones being orientated Lykens Valley No. 7, lies 50 to 110 feet below the Lykens parallel to bedding surfaces. The matrix is largely mod­ Valley No. 6 coal bed and 50 to 210 feet al 'we the base erate olive brown, greenish gray, and olive gray, which of the member. At several localities, the Lykens Val­ contrasts with the light-to dark-gray matrix of the ley No. 3% coal bed lies directly beneath or within 10 conglomerate of the Schuylkill and Sharp Mountain to 15 feet of the bottom of the basal conglomerate of Members. the Schuylkill Member (pi. 1, sees. 7, 11, 14) and at At natural exposures many cobbles and pebbles sepa­ one locality the Lykens Valley No. 3% coal bed lies rate from the matrix of weathered conglomerate in the directly beneath the conglomerate (pi. 1, sec. 3). Tumbling Run Member in a broken or fractured state. Most of the conglomerate, sandstone, siltstone, and At manmade exposures in roadcuts and strip-pit faces shale of the Tumbling Run is compositionally sub- unfractured cobbles and pebbles separate from the same graywacke but some beds are orthoquartzite. The con­ conglomerate. Cobbles and pebbles of the Schuylkill stituents of these rocks are similar, regardless of grain and Sharp Mountain Members are rarely fractured at size, and differ only in the percentages of the various weathered exposures. The general fractured condition minerals present. of the clasts at weathered outcrops of the Tumbling The mineral assemblage of the subgraywacke con­ Run, therefore, provides one of the more reliable means sists of grains of common and vein quartz, ilmenite, of distinguishing conglomerate of this member from magnetite, tourmaline, zircon, sphene, and leucoxene; tihat of the two overlying members. This difference in rock fragments of chert, schist, phyllite, slate, shale, fracturing of clasts suggests that the conglomerate of sandstone, and quartzite; extremely small amounts of the Tumbling Run was more firmly cemented than were andesine, oligoclase, kyanite, staurolite, garnet, epi- the conglomerates of the other members. When defor­ dote, sillimanite, limonite and hematite; plates and mation took place, incipient fractures developed in the irregular masses of biotite and muscovite; irregular clasts of the more firmly cemented Tumbling Run rocks masses and blebs of chlorite, sericite, and unidentified with the result that weathering cause them to disinte­ grate. In the less firmly cemented rocks of the other clay minerals. members, adjustments in the cement protected the Cementing media are silica, sericite, unidentified clasts from incipient fracturing. clay minerals, and a clastic binder of clay- and silt- Fine- to coarse-grained sandstone composes about 30 sized quartz fragments, and films of hematite, and percent of the Tumbling Run, but is largely concen­ limonite. Most very coarse grains are rounded to well trated in the upper part. Most sandstone 'beds are 2 to rounded. Very fine to coarse grains range from angu­ 15 feet thick, an appreciable number being 1 inch to lar to rounded and average subangular to subrounded. STRATIGRAPHY 73

SCHUYLKILL MEMBER Plates 1-3 illustrate three lines of stratigraphic sec­ The Schuylkill Member, medial division of the tions in and adjacent to the area. These lines show the Pottsville Formation, was named in 1956 (Wood and variations in lithology and thickness of the Pottsville others, p. 2671) for the Schuylkill Eiver. The member and Llewellyn Formations. Of the 46 illustrated sec­ includes the upper part of the Lower Intermediate Di­ tions, 24 include part or all of the Schuylkill Member. vision and all the Upper Lykens Division of C. D. The Schuylkill is about 300 feet thick in the north­ White (1900, p. 794-799). eastern part of the area on Broad Mountain and is The Schuylkill crops out in a long sinuous belt un­ about 700 feet thick in the southwestern part near derlying the crests or upper slopes of Bear, Big Lick, Lykens and Williamstown (fig. 37). The abundant Broad, Coal, Little, Mahanoy, Sharp, Sherman, Short, thickness data (pis. 1-3; fig. 37) indicate that the and Stony Mountains and Mine Hill (GQ-689, 690, member thickens southward at 30 to 60 feet per mile. 691, 692, 698, 699, 701). The surface of most of this Much structural information also indicates that the belt is smooth; but in a few places it is rough and Pennsylvanian rocks of the area were shortened an av­ steep, and locally, it is mantled by talus and covered erage of about 45 percent during the Appalachian by a heavy forest. orogeny. Thus, before the orogeny, the Schuylkill The basal conglomerate of the Schuylkill conform­ Member thickened southward at about 16-i/£ to 33 feet ably overlies finer grained rocks of the Tumbling Run per mile. Member. Weathered and fresh rocks of the member are light The upper contact of the Schuylkill is at the bottom to dark gray, the average being medium gray. At fresh of the basal conglomerate of the Sharp Mountain manmade outcrops, many rocks are lightly stainec1 by Member which rests conformably upon finer grained limonite. This staining is absent at most natural rocks in the upper part of the Schuylkill. The pebbles exposures. and cobbles in the basal conglomerate of the Sharp Most of the beds in the Schuylkill are tabular, but a Mountain Member are much coarser than those in the few are wedge shaped and irregular. Parallel-lamin­ underlying Schuylkill. This characteristic coarseness ated beds predominate over cross-laminated beds. The and the resistance of this conglomerate to erosion aid cross-stratification is in general simple and planar and greatly in distinguishing the boundary between these ranges from small to large. Most conglomerate and members. sandstone beds are 2 to 25 feet thick, and most shale 76°45' 76° 15' 40° , 45' KLINGERSTOWN

EXPLANATION

Isopachs Contour interval 50 feet X592 Measured thickness, ir feet 689 Computed thickness, H feet

BERKS CO SWATARA HILL

FIGUEE 37. Isopach map of the Schuylkill Member of the Pottsville Formation. 74 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA and silt-stone beds are y2 inch to 1% feet thick. Graded Anthracite field that is within the report, area. The No. and reverse graded beds are relatively common in the 1 bed is generally thin. However, it and the underlying coarser grained rocks. Carbonized plant fragments are Lykens Valley No. 4 bed of the Tumbling Run Member abundant in many shale units and are relatively com­ are perhaps the most widespread of the coal beds of the mon on bedding planes in the coarser grained rocks. Pottsville Formation. The consistent stratigraphic posi­ Conglomerate and conglomeratic sandstone compose tion of the No. 1 bed at 5 to 50 feet belovr the basal about 50 percent of the member. The pebbles in these conglomerate of the Sharp Mountain Member supports rocks are composed largely of vein quartz and quartz- the concept that the Schuylkill and Sharp Mountain ite. Chert is the next most common constituent. Schist, are conformable. phyllite, gneiss, sandstone, shale, siltstone, and granite The Lykens Valley No. 2 and No. \V2 cor,l beds thin pebbles are present, but in general, are sparse. Most of rapidly east of the latitude of Sherman and Little these clasts are well rounded and equidimeiisional to Mountains and are not recognized in the eastern part, ovoid. They are generally scattered evenly throughout of the area. a light- to dark-gray matrix consisting of very fine to The rocks of the member are compositionally proto- very coarse grains of quartz, quartzite fragments, quartzite and subgraywacke regardless of differences other rock fragments, and accessory mineral grains. in grain size. The principal mineral constituents of The largest clasts are usually concentrated in the basal both types of rock are grains of vein and common quartz conglomerate of the member, where they locally are and fragments of quartzite. Accessory minerals are as much as 3 inches in diameter. Pebbles in the overly­ varying amounts of ilmenite, magnetite, zircon, sphene, ing conglomerate beds rarely exceed 1 inch in diameter, tourmaline, rutile, and leucoxene; traces of andesine and average *4 to y2 inch. and oliogoclase; varying amounts of fragments of chert, Much of the conglomerate and conglomeratic sand­ schist, phyllite, slate, siltstone, and shale; irregular stone in the Schuylkill weathers into a pebble gravel masses and blebs of sericite, chlorite, biotite, muscovite, that is distinctive because of the small diameter, the hematite, limonite, and unidentified clay minerals; and well-rounded shape, and the unfractured condition of varying amounts of clay- to silt-sized quartz fragments. the pebbles. Cementing media are silica, sericite, clay minerals, a Sorting in the conglomerate and conglomeratic sand­ binder matrix of clay- to silt-sized quartz fragments, stone of the member is poor to moderate. Lineation at and films of hematite and limonite. Most of the coarse most localities is nil, except that the long axis of the to very coarse grains are well rounded, whereas the very more elongate and ovoid pebbles commonly parallels the fine to medium grains are generally subro\inded. The bedding. Cementation in these rocks is weak to quartz- margins of many quartz grains and quartzite fragments itic but generally is moderate. have been deeply sutured by pressure solution. The sandstone in the Schuylkill ranges from very SHARP MOUNTAIN MEMBER fine to very coarse grained and averages medium to coarse grained. It constitutes about 30 percent of the The Sharp Mountain Member, youngest division of member and is distributed evenly throughout. Most the Pottsville Formation, was named in 1956 (Wood sandstone beds are 2 to 15 feet thick, but some are as thin and others, p. 2671) for Sharp Mountain at Schuylkill as 1/2 inch. Graded bedding is more common in sand­ Gap. C. D. White (1900, p. 801) assigned the beds in­ stone than in the finer or coarser grained rocks. Sorting cluded in this member to his Upper Intermediate Divi­ ranges from moderate to excellent and averages good. sion of the Pottsville. He and Read (in Moore and Cementation generally is moderate but ranges from others, 1944, p. 680) recognized the persistence of the weak to quartzitic. basal conglomerate of this member throughout the Four relatively persistent beds of anthracite are pres­ Southern Anthracite field. ent in the member. In ascending order, these are the The member crops out at or near the crests of Bear, Lykens Valley Nos. 3, 2, 1%, and 1 coal beds (Wood Big Lick, Broad, Coal, Little, Sharp, Short, and Stony and Trexler, 1968b, c). Several thin and nonpersist- Mountains and Mine Hill (GQ-689, 690, 6P1, 692, 698, ent coal beds locally lie below the Lykens Valley No. 3, 699, 701). It is the principal "ridge former" in the and others are present between the Lykens Valley Nos. part of the coal field that is in the area. At most places 2 and iy2 coal beds. Only one of these, the Lykens it underlies cuestas or hogbacks covered by dense for­ Valley No. 3y2 coal bed, underlies an area large enough ests. Elsewhere, as on Broad Mountain, the member un­ to warrant naming. derlies a smooth rather featureless terrain. The Lykens Valley Nos. 3, 2, 1%, and 1 coal beds The contact between the Sharp Mountain and Schuyl­ are recognized at many places in the area. The No. 3 kill Members is at the bottom of the basal conglomerate and No. 1 beds underlie most of the part of the Southern of the Sharp Mountain Member, which res+s conform- STRATIGRAPHY 75 ably upon conglomeratic sandstone, sandstone, siltstone, Trexler, 1968b, sheet 3). The abundant thickness data in-, and shale in the upper part of the Schuylkill. The basal dicate that the member thins northwestward at about 40 conglomerate commonly weathers into a ledge, a series feet per mile in the northeastern part of the area, at of ledges, or a stone wall that rises above the finer 50 feet per mile in the central part, and at about 20 feet grained beds of the Schuylkill. In some localities it per mile in the southwestern part (fig. 38). Before the weathers into a gravel that mantles the surrounding crustal shortening resulting from the Appalachian orog­ terrain. eny, which is estimated to have been about 45 percent, The upper contact of the Sharp Mountain with the the member thinned northwestward at 22 feet, 27.5 Llewellyn Formation is at the base of the underclay feet, and 11 feet per mile, respectively. or shale that underlies the Buck Mountain (No. 5) coal The beds of the Sharp Mountain Member acc'unu- bed. Where the shale is absent, the contact is at the lated in a series of north- and northwest-trending thick base of the coal bed. and thin lobes. The conglomerate in the thick lobes con­ The Sharp Mountain Member is the most distinctive tains cobbles as much as 8 inches in diameter, whereas stratigraphic unit in the Pottsviile and Llewellyn For­ the cobbles in the thin lobes reach a maximum diameter mations. Its widespread distribution and characteristic of about 5 inches (fig. 39). The greater size of the cob­ conglomerate lithology are helpful in determining the bles in the thick lobes suggests that these lobes were the base of the Llewellyn and in delineating structural sites of large alluvial fans formed by streams capable features that cross the outcrop belt. of transporting much larger and heavier detritus than Plates 1-3 illustrate three lines of stratigraphic sec­ the streams that deposited the material in the thin lobes. tions within and adjacent to the area. These lines of The thin lobes, in fact, may represent interfan alluvia- sections show 46 localities where the thickness and tion from small streams. lithology of the Pennsylvania!! rock sequence has been Fresh and weathered rocks in the Sharp Mountain measured and studied. Of the 46 sections, 31 include Member are principally medium gray, but they range part or all of the Sharp Mountain Member. The mem­ from light to dark gray. ber is thickest, 315 ± feet, in the vicinity of Tower City Tabular and lenticular beds are about equally tf.bun- No. 1 Tunnel (pi. 1, section 10; Wood and Trexler, dant in the member. Wedge-shaped and irregular beds 1968b, sheet 4) and is thinnest, 120dr feet, north of are uncommon. Most strata are cross laminated, but Colket Water Level Tunnel (pi. 1, section 17; Wood and many are parallel laminated. The attitudes of the small-

76-15'

EXPLANATION -250- -200- Isopachs Contour interval 50feet X225 Measured thickness, in feet ,250± Computed thickness, in feet

BERKS CO SWATARA HILL

FIGURE 38. Isopach map of the Sharp Mountain Member of the Pottsviile Formation. 316-352 O 69 6 76 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA to large-scale simple and planar cross-strata and the ite, and small percentages of chert, schist, gneiss, sand­ orientation of ripple marks generally indicate deposi­ stone, slate, siltstone, and granite. Most are rounded to tion from northwest-flowing currents. Most beds are 4 well rounded and are scattered evenly in a very fine to to 10 feet thick; the rest range in thickness from 4 very coarse grained light- to dark-gray matrrx. inches to 4 feet. Conglomerate and sandstone beds are The conglomerate of the Sharp Mountrin Member generally thicker than adjacent siltstone and shale beds. weathers at many places into a gravel that mantles the Graded bedding is common, and reverse grading, al­ outcrop belt and adjacent rock units. This gravel is though well developed locally, generally is rare. Plant distinctive because of the coarseness, rounded and well- debris is abundant in all rock types, but is well pre­ rounded shape, and unf ractured condition of the cobbles served only in siltstone and shale. and pebbles. Conglomerate is largely concentrated in the basal part Sorting in the conglomerate of the Sharp Mountain of the member, and finer grained rocks predominate in ranges from poor to excellent and averages moderate to the upper part. Over most of the area, the Sharp Moun­ good. There is little apparent lineation of tH clasts, ex­ tain is composed of about 45 percent conglomerate, 25 cept that the long axis of the more elongate and ovoid percent conglomeratic sandstone, 15 percent sandstone, ones commonly parallels the bedding. Most of the con­ 5 percent siltstone, 9.5 percent shale, and 0.5 percent glomerate is well cemented, but locally, the bonding anthracite. From south to north across the area, the ranges from weak to quartzitic. percentage of conglomerate decreases slightly and the Fine-grained to very coarse grained sandstone is percentage of sandstone increases proportionately. largely concentrated in the upper part of the member. At places on Sharp and Broad Mountains, cobbles Sandstone beds are 2 inches to 20 feet thick, but most and pebbles in the basal conglomerate of the Sharp are between 2 and 5 feet thick. Tabular bedded units Mountain Member reach a maximum diameter of 8 predominate, lenticular units are relatively common, inches. The average diameter of the clasts in this unit and wedge-shaped and irregular units are rare. Many is about three-quarters of an inch for the area as a beds are crossbedded, and the rest are parallel laminated. whole. Above the basal conglomerate the clasts reach a Most of the shale and siltstone is in the upper part of maximum diameter of about 2 inches, but generally are the Sharp Mountain Member and is in beis 1 inch to less than half an inch in diameter. They are composed 2 feet thick. Locally, however, some beds are as thick of 60 to 85 percent vein quartz, 15 to 35 percent quartz- as 10 feet. Nearly all the shale and siltstone is carbona-

;6°45' 76-15' 40° 45' KLINGERSTOWN

EXPLANATION

Contours of maximum di­ ameter of pebbles and cobbles. Dashed where approximately lo­ cated. Contour interval 1 inc h

Observed mf ximum diameter of pebbles and cobbles, in inches

BERKS CO SWATARA HILL

FIGURE 39. Contour map of maximum diameter of pebbles and cobbles in the Sharp Mountain Member of the Pottsville Formation. STRATIGRAPHY 77 ceous and contains much macerated to well-preserved grains are commonly sutured deeply by pressure solu­ plant debris. tion, but where they are surrounded by a matrix of Three anthracite beds are present in the upper part of mica and clay minerals, their original shapes are pre­ the member. In ascending order, these are the Scotty served and suturing is negligible. Steel Nos. 2 and 3 coal beds and the Little Buck Moun­ THICKNESS OF THE POTTSVILLE FORMATION tain (No. 4) coal bed. The Scotty Steel beds underlie much of the area (Wood and Trexler, 1968b, c). The The Pottsville Formation thins northwestward from No. 3 bed is slightly thicker and more widespread than about 1,500 feet on Sharp Mountain to about 800 feet the No. 2 bed. The Little Buck Mountain coal bed is on Broad Mountain (fig. 40). Thickening of the forma­ known only in the northern and central parts of the tion southeastward at the southernmost outcrops on Minersville quadrangle (Wood and Trexler, 1968b, Sharp Mountain indicates that the axis of the Potts- sheets 1, 2). Aalle depositional basin lay south of this mountain, but The conglomerate, sandstone, and shale of the Sharp the distance to the axis is unknown because of erosion. Mountain Member are compositionally protoquartzite DEPOSITION OF THE POTTSVILLE FORMATION and subgraywacke. The principal constituents of both rock types are grains of vein and common quartz and Sediments of the Pottsville Formation accumulated fragments of quartzite. Other constituents are frag­ on a broad flood plain that overlay a slowly subsiding ments of chert, schist, gneiss, slate, siltstone, and sand­ asymmetric depositional basin. They were laid down stone ; plates, blebs, and irregular masses of muscovite, as fluvial and swamp deposits. The gray and olive colors biotite, chlorite, sericite, and unidentified clay minerals; oi the rocks, the preservation of carbonaceous mr.terial grains of ilmenite, leucoxene, magnetite, sphene, tour­ in rocks of all types, and the presence of anthracite all maline, and zircon; sparse grains of andesine, stauro- suggest that deposition was in a reducing environment. lite, epidote, and rutile; films of hematite and limonite; Many swamps existed during deposition, and the vege­ and varying amounts of silt- and clay-sized quartz frag­ table matter that accumulated in them was later trans­ ments. Grains of quartz, chert, and quartzite range from formed into coal in the numerous anthracite beds. subrounded to well rounded but average rounded. In The end of Pottsville deposition was marked by the contrast, other types of grains are generally sub- formation of a very large swamp in which the vegetable rounded. The margins of many quartz and quartzite matter of the Buck Mountain (No. 5) and correlative

EXPLANATION

Isopachs Contour interval I'M feet X1340 Measured thickness in feet .925 Computed thickness in feet

BERKS CO SWATARA HILL

FIGURE 40. Isopach map of the Pottsville Formation. 78 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA coal beds accumulated. This swamp apparently extended observations by the authors indicate that 10- to 12-inch over the entire Anthracite region and may have ex­ boulders mark the fall line of the Atlantic Coastal tended into parts of western Pennsylvania, West Vir­ Plain. Many more data would be required than are now ginia, and Ohio. The concept that this swamp extended available to determine accurately the average maximum over such a large area is based upon the paleobotanical size of these boulders. Nevertheless, the size is much equivalency of the Buck Mountain coal bed of the An­ greater than that advocated by Pelletier. If stream thracite region and the Lower Kittanning coal bed of the velocities and gradients in the Pottsville source area Allegheny Formation of western Pennsylvania (C. B. were similar to those of the modern Piedmont, it seems Eead, oral commun., 1954). likely that the Pottsville fall line would also have been Sedimentary structures, thickness patterns, and the marked by 10- to 12-inch boulders. direction of increase in grain size indicate that the rocks When the effects of crustal shortening have been nul­ of the Pottsville were derived from a source southeast lified by using the data determined by the authors and and east of the area. During late Mauch Chunk time, a Drake, a Pottsville fall line based upon 10- to 12-inch large part of the source region was uplifted by the first boulders lay at about the position of the modern Read­ pulsation of the Appalachian orogeny. Coarse detritus ing Prong, or about 40 miles northwest of the 6-inch fall from this uplifted part of the source region accumulated line determined by Pelletier. The is in the area during deposition of the upper member of the underlain by metamarphic and ? similar to Mauch Chunk and the lower part of the Tumbling Run those believed to have supplied much of the detritus pre­ Member of the Pottsville. The rocks of the upper part of served in the Pottsville. the Tumbling Run and the Schuylkill Members are finer The Tumbling Run and Sharp Mountain Members grained than those of the lower part. This decrease in of the Pottsville Formation and the upper member of grain size probably records the erosional reduction of the Mauch Chunk Formation are the only stratigraphic the source region and marked the end of the first units in the area in which garnet, epidote, staurolite, pulsation of the orogeny. kyanite, and sillimanite and clasts of gneiss and granite Shortly before the end of Schuylkill deposition, the have been found. These minerals and clasts suggest that second pulsation of the Appalachian orogeny rejuve­ an igneous mass and a high-temperature ixntamorphic nated the source. A large volume of coarse detritus was mass were exposed in the source region.

eroded from the uplifted region and is preserved in the AGE AND CORRELATION OF THE POTTSVILLE FORMATION lower part of the Sharp Mountain Member. During deposition of this member, the second pulsation lessened The Pottsville Formation is of Early r.nd Middle in intensity, and finer detritus was eroded thereafter Pennsylvania age (Read and Mamay, 1960, table 176.1). from the source. This finer detritus is preserved in the For many years the formation at its type section has rocks of the upper part of the Sharp Mountain Member been considered the type basal unit of the Pennsyl­ and the lower part of the Llewellyn Formation. vanian System. Pelletier (1958, p. 1059-1060) postulated that the fall The Tumbling Run Member of early Early Pennsyl­ line of the Pottsville Formation lay near Philadelphia. vanian age contains fossil plants of the zone of Neurop- He determined the fall line by preparing a location teris pocahontas and Mariopteris eremopteroides and graph of maximum pebble and cobble sizes from which of the overlying zone of Mariopteris pottsvillea and the effects of deformation were removed by using crustal Aneimites spp. These plants indicate that the member shortening data calculated by Cloos (1940, p. 841). His correlates with the and the lower fall line was based upon the location where 6-inch cob­ parts of the Lee and New River Formations of southern bles theoretically would have been deposited. West Virginia, southwestern Virginia, Kentucky, and Crustal shortening in the Pennsylvanian rocks of the Tennessee. area averages 45 percent, or 15 percent more than the The Schuylkill Member of late Early Pernsylvanian value determined by Cloos (1940, p. 847). South of the age contains plant remains from the zone of Mariop­ report area, in the Great Valley and Piedmont regions, teris pygmaea and Neuropteris tennesseeana. These crustal shortening was a minimum of 50 percent (A. A. fossils indicate that the Schuylkill correlates with the Drake, Jr., oral commun., 1962), or 10 percent more than upper part of the , the Bloyd the value calculated by Cloos. Shale of the Morrow Series (Read and Mamay, 1960, Cobbles as much as 8 inches in diameter are present table 176.1), and with the upper part of tl «, Lee For­ in the Pottsville Formation on Sharp Mountain (GQ- mation of southwestern Virginia, Kentucky, and Ten­ 689, 690, 691). Obviously, these cobbles were deposited nessee (Read, 1947, table 1). Bode (1958, p. 254) as­ below a fall line. Therefore, 6-inch cobbles did not mark signed the flora of the Lykens Valley No. 1 coal bed to the Pottsville fall line as advocated by Pelletier. Casual the Westphalian zone A of Europe. STRATIGRAPHY 79 The upper part of the Sharp Mountain Member con­ been eroded into a trellis drainage pattern. The drain­ tains a fossil flora of the zone of Neuropteris rarinervis age system has been greatly modified at many hundreds and the upper part of the zone of Neuropteris tenuifolia of places by strip and underground mining for anthra­ (Wood and others, 1956, table 2) or Westphalian zone D cite. of Europe (Bode, 1958, p. 254). The lower part of the The contact between the Llewellyn Formation and the zone of Neuropteris tenuifolia and the zone of Nega- underlying Sharp Mountain Member of the Pottsville lopteris spp., and their European equivalents West­ Formation is placed at the base of the underclay or phalian zones B and C, may be present in the lower shale of the Buck Mountain (No. 5) coal bed. In a few coarsely conglomeratic sequence of the member, but localities the shale is absent, and the contact is placed they have not been identified (Wood, and others, 1956, at the base of the coal bed. The upper limit of the p. 2684-2'685). Llewellyn is the present erosion surface at most places, The upper beds of the Sharp Mountain Member cor­ but in a few places the formation is overlain by Quater­ relate with the lower part of the Allegheny Formation nary alluvium. of western Pennsylvania, Ohio, and West Virginia, and The Llewellyn reaches a maximum thickness of about with the lower part of the Des Moines Series of the 3,500 feet in the central part of the Minersville qnad- midcontinent region. The lower part of the member raiigle near the village for which it was named. It is probably correlates with the of impractical to construct a thickness map of the for­ West Virginia, Virginia, and Kentucky. mation because of structural complications and the Eead and Mamay (1960, table 176.1) classified the small area in which the youngest beds are preserved. Sharp Mountain as late Middle Pennsylvanian. The The thickness and lithology of the lower and middle Buck Mountain (No. 5) coal bed at the base of the parts of the Llewellyn Formation are illustrated r,t 39 Llewellyn Formation contains latest Middle Pennsyl­ localities (pis. 1-3). The upper part is so poorly exposed vanian plants of the zone of Neuropteris rarinervis; that its variations in thickness and lithology coulc1 not the authors, therefore, tentatively suggest that the mem­ be determined and studied. The lower and middle parts ber may represent all but the uppermost part of Middle of the formation are characterized by many lateral vari­ Pennsylvanian time. ations in rock type. Despite these variations, the con­ tinuity and equivalency of thin to thick rock sequences LLEWELLYN FORMATION over large areas is indicated by the associated anthracite beds. The persistency of the anthracite beds has been The Llewellyn Formation was named in 1962 (Wood proven by mapping and by underground and strip and others, p. C41-C42) for a town in the Minersville mining. It is impossible, however, to show many of the quadrangle. The rocks assigned to this formation were data that prove this persistency on the coal maps and originally referred to an informal stratigraphic unit coal structure sections prepared simultaneously with known as the "coal measures" (Smith, 1895, p. 1920). this report (Wood and Trexler, 1968b, c). Geologists later assigned them to the Allegheny and The Llewellyn is characterized by sharp thickness Conemaugh Formations (Willis, 1912, 439-442; Loh- changes between datum horizons that are only a few man, 1937, p. 47; Eothrock and others, 1950) and to an feet to several hundred feet apart. It is also character­ informal unit known as post-Pottsville rocks (Wood ized by rather even or uniform thicknesses between and others, p. 2678, fig. 3, and table 2). datum horizons that are much farther apart. For ex­ Much of the complexly folded and faulted Miners­ ample, local thickness variations are numerous and ville synclinorium is underlain by the Llewellyn Forma­ sharp between the Buck Mountain (No. 5) coal bed and tion (GQ-689, 690, 691, 692, 698, 699, 701; Wood and the coal beds of the Mammoth coal zone, between in­ Trexler, 1968b, c). The west-central part of the Southern dividual coal beds of the Mammoth coal zone, and be­ Anthracite field is underlain by this formation and by tween the uppermost coal bed of the coal zone and the the Pottsville Formation. Diamond (No. 14) or Peach Mountain (No. 18) coal There are few natural exposures of the rocks of the beds (pis. 1-3). However, the average thickness be­ formation, but there are many manmade outcrops in tween the Buck Mountain and Diamond coal beis is strip pits and in underground mines. Millions of tons about 900 feet, and the greatest variation in thicl-ness of debris from these strip pits ,and underground mines between these beds is 775 to 950 feet. Similarly, the have been dumped between the strip pits; therefore, average thickness between the Buck Mountain and much is known about the rocks in the pits, but relatively Peach Mountain coal beds is about 1,400 feet, and the little is known about the rocks between them. variation is only 1,300 to 1,475 feet. The sharp local The Llewellyn underlies a series of gentle to steep, variations between nearby datum horizons probably re­ rolling to rough parallel ridges and valleys that have sulted from unequal volumes of sediment of different 80 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA grain size being deposited from place to place at the chert, schist, gneiss, slate, sandstone, siltstone, and shale. same time. The overall uniformity in thickness between The percentage of clasts derived from metamorphic datum horizons that are many hundreds of feet apart terranes seems to increase stratigraphically upwarda seems to be due to each part of the basin of deposition Most of the conglomerate in the Llewellyn is poorly being filled by approximately equal volumes of each to moderately sorted. However, locally, some is well textural size. sorted and closely resembles the basal conglomerate of Freshly broken rocks of the Llewellyn Formation the Sharp Mountain Member of the Pottsville are very light to dark gray, grayish black, light brown­ Formation. ish gray, greenish gray, and grayish orange. Weathered Fine- to coarse-grained sandstone is presert through­ rocks are commonly the same colors, but are also pale out the Llewellyn. The bedding ranges in thickness from to light brown, pale to dark yellowish brown, and light 1/2 inch to 15 feet and averages about 1 foot 6 inches. olive gray. Many weathered rocks have a salt-and- Tabular beds predominate, but lenticular beds are com­ pepper appearance where hues of gray are combined mon, and wedge-shaped and irregular beds are abun­ with the colors listed above. dant locally. Although most strata are parallel lami­ Tabular, lenticular, and wedge-shaped beds are com­ nated, small- to large-scale simple and planar cross- mon in the Llewellyn. Most beds are 1 to 2 feet thick, strata are common at many places. but some are as thin as half an inch, and others are as Most siltstone and shale beds are 1 inch to £ feet thick, thick as 20 feet. Thin- to thick-channel sandstone de­ but many sequences of these beds are 20 to 5C feet thick. posits are present at many places but are sparse enough Much of the siltstone and shale is carbonaceous and to be noteworthy. Many beds are graded, but reverse commonly contains large amounts of plant debris and grading is rare. Although parallel laminations predomi­ intercalated beds of anthracite at many places. The nate over cross-laminations, small to large simple and underclay or shale of some anthracite beds is charac­ planar cross-strata are abundant. The cross-laminations, terized by abundant Stigmaria impressions, and a few ripple marks, oriented plant fragments, and the direc­ beds contain upright tree trunks. Well-preserved plant tion of increase in pebble diameters generally indicate leaves and stems are common in the roof shales of many deposition by streams flowing from the southeast. The anthracite beds. ripple marks and oriented plant fragments are pre­ Forty beds of anthracite are economically and strat­ served principally in very fine grained to medium- igraphically important enough to be identified in this grained sandstone, siltstone, and silty shale. Well-pre­ report by name and number or only by number (Wood served plant fossils are most common in shale adjacent and Trexler, 1968b, c). The beds have beer numbered to anthracite beds, but macerated plant debris is abun­ from the base of the formation upward, starting with dant in all rock types. 5 and ending with 29. Conglomerate and conglomeratic sandstone are scat­ The more widely persistent and thicker ba.ds of an­ tered at random in the Llewellyn. Most are in small thracite are the Buck Mountain (No. 5) coal bed, Skid- lenticular bodies, but several conglomerate lenses be­ more (No. 7), Bottom Split (No. 8), Middle Split tween the Buck Mountain (No. 5) coal bed and the Bot­ No. 8i/2 ), Top Split (No. 9), Holmes (No. 10), Prim­ tom Split (No. 8) coal bed are widespread in the Miners­ rose (No. 11), Diamond (No. 14), Tracy (Fo. 16), and ville and Tremont quadrangles (GQ-690, 692). A con­ Peach Mountain (No. 18) coal beds. These b^ds are con­ glomerate bed overlies the roof shale of the Primrose fined to the lower 1,475 feet of the formation, and most (No. 11) coal bed and is traceable over much of the lie in the lower 650 feet. Tower City (GQ-698), Tremont, Pine Grove (GQ- Eleven other, generally thinner, slightl;T less per­ 691), and Minersville quadrangles. A series of wide­ sistent, and somewhat more lenticular coal beds are in spread conglomerate beds crop out in the southern part the lower 1,600 feet of the Llewellyn. They are the Seven of the Minersville, Pine Grove, and Swatara Hill (GQ- Foot (No. 6), Lower Four Foot (No. 9%), Orchard 698) quadrangles between the 22-25 coal beds. (No. 12), Little Orchard (No. 13), Little Diamond The conglomerate beds below the Peach Mountain (No. 15), Clinton (No. 15%),Little Clinton (No. 15%), (No. 18) coal bed contain pebbles as much as 2 inches in Upper Four Foot (No. 16%), Little Tracy (No. 17), diameter and average half an inch. Conglomerate above Tunnel (No. 19), and Babbit Hole (No. 20) coal beds. this coal bed commonly contains pebble averaging about Numerous, local, lenticular, and general!^ thin beds three-quarters of an inch in diameter and locally con­ of anthracite are present at many places in the area. tains cobbles as much as 3 inches in diameter. These From the base upward the economically and strat­ large clasts are composed mainly of vein quartz with igraphically more important of these anthracite beds substantial amounts of quartzite and lesser amounts of are the 6L, 7L, 8%, 10L, 13%, Diamond Leader (14L), STRATIGRAPHY 81 14y4, uy2 Faust (No. 20), 22, 22L, 23, 23%, and contrast, the greater areal extent of the coarse detrtal 29 coal beds. deposits and the greater average diameter of the clasts The conglomerate, sandstone, siltstone, and shale in in the upper part of the formation suggest that the the Llewellyn is predominantly subgraywacke. Some of uplifted parts of the highland were considerably larger the coarser grained sandstone and conglomerate ap­ than they had been earlier or that they had advanced proaches protoquartzite in composition and is here clas­ northwestward towards the report area. sified as "clean" subgraywacke. The rocks in the lower The lithology, sedimentary features, and plant fos sils part of the formation contain higher percentages of of the finer grained rocks of the Llewellyn indicate that common and vein quartz and smaller percentages of these rocks were carried onto the flood plain by mean­ rock fragments, unidentified clay minerals, sericite, and dering sluggishly flowing streams. The flood plain other mica minerals than do those in the upper part. The apparently had little topographic relief and was easily principal constituents of Llewellyn rocks are common flooded by slight changes in base level, precipitation, or and vein quartz, fragments of quartzite, and blebs and depositional habits of streams. Such changes resulted plates of sericite and muscovite. Other constituents are in repeated flooding of parts of the flood plain and the fragments of chert, schist, slate, and siltstone; blebs of development of local and regional swamps that, in some chlorite; grains of ilmenite, leucoxene, magnetite, rutile, instances, covered hundreds of square miles. Abrupt tourmaline, zircon, and sphene; films of limonite and lithologic changes from conglomerate and coarse­ hematite; a few grains of andesine; rare interstitial grained sandstone to carbonaceous shale, siltstone, and fillings of halloysite; and varying amounts of uniden­ anthracite indicate that in many places the transition tified clay minerals, silt- and clay-sized fragments of from fluvial to swamp deposition, and the reverse was quartz, and carbonaceous material. rapid. Vegetation grew rapidly and profusely in the The rocks of the Llewellyn are cemented principally swamps. The 20 to 40 feet or more of anthracite pre­ by silica, sericite, and silt- and clay-sized quartz frag­ served locally in coal beds of the Mammoth coal zone ments. Other cements are limonite, hematite, clay min­ (pis. 1-3) indicate that such growth apparently con­ erals, and carbonaceous material. Grains of quartz and tinued for long periods of time. Calculations based upon fragments of chert and quartzite range from angular to Ashley's (1907, p. 42) rates of deposition of vegetable well rounded and average rounded. Other rock frag­ material converted to old peat and coal indicate that the ments and grains range from angular to rounded and 40 feet or more of anthracite locally present in individ­ average subrounded. Chert fragments are generally bet­ ual beds of this zone accumulated during periods of as ter rounded than are other constituents. Many quartz long as 12,000 years. Most beds of anthracite in the r.rea grains and quartzite fragments are deeply sutured, but are considerably less than 40 feet thick and therefore, where they are embedded in a fine-grained matrix of took far less time to accumulate, the numerous anthracite nonquartz minerals, suturing generally is absent. beds, however, undoubtedly indicate that many swamps Llewellyn sediments accumulated in an oxygen-poor existed for hundreds, and in some instances for thou­ or reducing environment upon a broad flood plain as sands, of years during Llewellyn time. fluvial and swamp deposits. The flood plain was The swamps of the Llewellyn were each successively bounded to the southeast by a nearby highland area that destroyed by blankets of fine to coarse detritus f " om had been uplifted during late Mauch Chunk and Potts- the highland southeast of the flood plain. No regional ville time. It was bounded to the west and northwest blankets of coarse sand and gravel seem to have 1 ?en by a distant fluctuating coastline. A slowly subsiding deposited during accumulation of the lower and middle asymmetric depositional basin underlay the flood plain. parts of the Llewellyn, but many extensive coarse sr.nd- The short southeastern limb of the basin probably ex­ stone and conglomerate sequences were deposited dur­ tended only a few miles southeast of the report area. The ing accumulation of the upper part. These more ex­ much broader northwestern limb may have extended tensive coarse deposits record uplift and erosion of the into central and north-central Pennsylvania. highland mass that lay southeast of the area during The scattered conglomerate, conglomeratic sandstone, the third major pulsation of the Appalachian orogeny. and coarse-grained sandstone of the Llewellyn indicate The oregony may have consisted of more than three that the highland area southeast of the report area was major pulsations, but this is uncertain because Paleozoic uplifted intermittently. The small areal extent of the rocks younger than the Llewellyn have been removed by coarse detrital deposits and the small average size of the erosion. If there were only three pulsations, the course clasts in the lower and middle parts of the formation detritus in the upper part of the formation presumably suggest that uplifted parts of the highland were eroded records the beginnings of the pulsation that later ad­ quickly during early and middle Llewellyn time. In vanced northwestward and deformed the area. How- 82 GEOLOGY, SOUTHEKN ANTHRACITE FIELD, PENNSYLVANIA ever, several pulsations unrecorded by sedimentation relates with the upper part of the Allegheny and the may have taken place before the orogeny drew to an lower part of the Conemaugh Formation and, in addi­ end. tion, stated that the youngest rocks of th?, Llewellyn The Llewellyn Formation is of latest Middle Penn- contain fossil plants characteristic of the D zone of the sylvanian and^ate Pennsylvanian age. Its plant fossils Westphalian Stage of Europe. were originally studied by Lesquereux (1880-84). Sub­ sequently, Read (in Wood and others, 1956, table 2; in QUATERNARY DEPOSITS Wood and others, 1958, table 1) concluded that the rocks The youngest naturally occuring sedimentary depos­ of the formation contained fossil plants from the up­ its of the report area are and Recent talus per part of his zone of Neuropteris rarinervis, and from and alluvium. Recent manmade deposits of mine waste his zone of Neuropteris flexuosa and Pecopteris spp. resulting from the intensive mining have been indis­ C. D. White (1900, p. 830) stated that the lower unit criminately deposited during the last 150 years on the of the formation, the Buck Mountain (No. 5) coal bed, Pottsville and Llewellyn Formations as w?!l as on the correlates with the Lower Kittanning coal bed in the talus and alluvium. middle part of the Allegheny Formation of central TALUS and western Pennsylvania. Read (oral commun., 1954, 1955; written commun., 1955; in Wood and others, 1956, Extensive talus fields rest unconformabbT on the un­ table 2; in Wood and others, 1958, table 1) confirmed derlying rocks and blanket the slopes of many of the this correlation and stated that these coal beds contain mountain ridges in the area. The larger of these fields a flora characteristic of the upper part of his zone of are on the slopes of Bear, Big Lick, Blue, Broad, Coal, Neuropteris rarinervis. In 1960, Read and Mamay (p. Line, Little, Mahantango, Second, Sharp, Sherman, B381) assigned the zone of Neuropteris rarinervis to the Short, and Stony Mountains (GQ-689, 690, 691, 692, Middle Pennsylvanian but incorrectly indicated that 698, 699,700,701). Many other smaller fields are present the basal part of the Llewellyn equivalent to the post- in the area, but are not shown on the maps of this report. Pottsville rocks of Wood, Trexler, Arndt, Yelenosky, The talus fields generally are only a few tens of feet and Soren (1956, p. 2678), which includes the Buck thick and are composed of small to large rectilinear Mountain coal bed, was entirely in the zone of Neurop­ blocks of sandstone and conglomerate mixed with teris flexuosa and Pecopteris spp. Thus, despite Read smaller fragments derived from siltstono, shale, and and Mamay's 1960 placing of the rocks equivalent to anthracite beds. the Llewellyn in the Upper Pennsylvanian, Read's At many places talus deposits have hampered the dis­ 1954-58 identifications indicate that the basal part of covery and exploitation of coal beds in the Pottsville the formation is of latest Middle Pennsylvanian age. and Llewellyn Formations. Numerous deposits mantle Information is scant concerning the fossil plants in considerable areas in the west-central part of the South­ Pennsylvanian rocks younger than the Pottsville For­ ern Anthracite field. mation. Table 1 shows the observed range of fossils in The talus fields appear to have been forming since at the area. It was compiled from field and office identifi­ least the beginning of Pleistocene time. This age assign­ cations by Read, Mamay, and Bode and from published ment is based on the fact that glacial deposits in nearby identifications by Bode (1958, p. 253-254). Fossils were areas are adjusted to preexisting topography similar to not collected from above the Faust (No. 21) coal bed that in the area, which suggests that the relief of the because they are so poorly preserved and fragmental area was partially developed before glaciation. Some that they are largely unidentifiable. Some species may talus deposits, therefore, must have been forming before have actual ranges, therefore, which extend above the the beginning of glaciation. Faust. All fossils listed are from the floor or roof shales of coal beds. ALLUVIUM According to Read (in Wood and others, 1956, table Alluvial deposits, which rest unconformably upon 2) and Read and Mamay (1960, table 176.1), the rocks underlying rocks, are shown only on th«s quadrangle included in the Llewellyn Formation correlate with the maps (CQ-689, 690, 691, 692, 698, 699, 701, 701) along upper part of the Allegheny Formation and the lower Deep, Little Mahantango, Lower Little Pwatara, Ma- part of the Conemaugh Formation of central and west­ hanoy, Mahantango, Mill, Pine, Swatara, Upper Little ern Pennsylvania, Maryland, Ohio, and West Virginia Swatara, and Wiconisco Creeks. Most of these deposits and with the upper part of the Des Moines Series of the are thin, but they commonly mask the outcrops of strati- midcontinent region. Bode (1958, p. 254 and fig. 13) graphic units, folds, and faults in the valleys of these agreed with Read and Mamay that the Llewellyn cor­ creeks. 13 ^ J- to to . S 1 13 B r^ r^ 33 ? * fej * % % > !j» S! S ^ ^5 f3 O bo Ju tu 3- L. 1» -5 * s V ^ ^ ^ 2 5 - ~k ~ 2 s n n ->- ~»-, K ~ § S = S" ^' £ -s n 5 i. "S. ~" * S" "f s ~ > 2 ° S' 5" C. 5 CJ 5 = 2 S' S ^ 5 a"S 5 = S" *3 ^ it ~:. S" a 5. "5 5- 1 ? 1 1 1 f = -t. ^ «i S S- ? i I i I S S ^ £ ^Ts 3" ^ '"S ' S' J3 - K S' S; * 2 !SL A 1' t- a |. 2. i?" * ~. X -^ < ~- ^ H i ^ 4 1_ i. ~ B-3 1 ~ cc " b "*S 3 S- 2 r V 2. 2 J 1 1 1 1 1 c- ^J-s i i ? ^5 S 1 i i 1 1 1 i i 5 I 2 i i 1 1 1 1 1 ~ 1 ~ i i 1 1 1 i i **' 1 i i 1 1 1 i i i 1 i i I 1 1 i i i

f%

Buck Mountain * 1 t \ I (No. 5)

Bottom Split (No. 8)

Holmes (No. 10) Bl 0 r t Orchard (No. 12) o EL 1 cr S- t Diamond (No. 14) P f GJs M O c 5 a 3 Tracy (No. 16) 1 3 .=" \ \ cr o' 3 Upper Four Foot (No. 16%)

Peach Mountain j (No. 18)

I t * ' t Faust (No. 21)

00 CO 84 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA Deposits of alluvium are present along most of the and their subsidiary folds are numerous small to large permanent stream courses in the Southern Anthracite thrust, underthrust, high-angle reverse, bedding-plane, field, but they are not shown on the coal maps or quad­ and tear faults. rangle maps because they would make the maps unnec­ essarily difficult to read. STRUCTURAL FEATURES FORMED DURING THE TACONIC OROGENY In addition to the naturally developed alluvial depos­ its, many hundreds of large to small deposits of mine The Taconic orogeny of Late Ordovickn time pro­ waste have been derived from strip pits, underground foundly affected the region south, southeast, and east of mines, and breaker plants. Most underground mine- the area. Its effects are poorly known in the area be­ waste deposits were accumulated during the period cause rocks of Odrovician age are largely covered. How­ from 1870 to 1945 and the strip-pit waste deposits, since ever, these rocks were folded during the disturbance, 1930. then eroded, and finally, covered unconfornably by the The natural alluvial deposits are Pleistocene and Re­ Tuscarora Sandstone of Early Silurian age. The un­ cent. This age assignment is based on the assumption conformity is not exposed in the area, but is believed that most stream channels probably had their greatest to be angular as it is to the east at Schuylkill Gap in development during the advances and retreats of the Blue Mountain. Some field evidence observed on Blue of Pleistocene time. Therefore, it seems prob­ Mountain and to the south in the southern part of the able that part of the detritus in these deposits accumu­ Swatara Hill quadrangle (GQ-689) supports this belief. lated during these advances and retreats and that the In these localities the Tuscarora Sandstone dips 35° to rest was laid down in Recent time. 45° N., and the Martinsburg Shale, about 4,000 feet to the south, dips 10° to 45° S. There is no indication of STRUCTURE a modern anticline between these exposure?; therefore, The rocks of the area have been folded and faulted when the Tuscarora Sandstone was deposited, the Mar­ during three episodes of mountain building: the Ta- tinsburg beds probably dipped 45° to 90° S. conic, Acadian, and Appalachian orogenies. Structural STRUCTURAL FEATURES FORMED DUB ING THE features that formed during the Appalachian orogeny ACADIAN OROGENY are superimposed on and obscure those formed during the earlier orogenies. Consequently, much more is A few structural features that formed during the known and described below about the structural fea­ Acadian orogeny of Late Devonian and Early Missis- tures formed during the Appalachian orogeny than sippian time have been identified in the area. about those of the earlier events. The Spechty Kopf Member of the Catskill Formation The report area lies in the southeastern part of a is overlain angularly by the Beckville Member of the large poorly defined north-northeast-trending struc­ Pocono Formation on Broad and Peters Mountains in tural depression or sag that occupies much of east- the southern part of Lykens quadrangle (GQ-701), central and northeastern Pennsylvania (Gray and (Trexler and others, 1961, fig. 38.2). Structural atti­ others, 1960). The depression has been largely obscured tudes indicate that rocks of the Spechty Kor>f dipped an by a multitude of superimposed east-northeast-trending average of 20° N. when the Beckville was deposited. faults and folds. The trough of the depression, which is Several miles north of Broad and Peters Mountains interrupted at many places by the superimposed faults in Rattling Creek gorge through Berry Mountain (GQ- and folds, is sinuous and trends about N. 20° E. from 701), a generalized anticinal feature consisting of two the vicinity of Pottsville to the vicinity of Wilkes- anticlines and a syncline in the Spechty Koftrf Member of Barre, both of which lie east and northeast of the area. the Catskill is overlain by a single anticline in the Beck­ Structurally, the boundary of the depression is difficult ville Member of the Pocono. Locally, th^ angularity to define; but to the north it is at the structural front of between the beds of these members is as grer,t as 75°. the Appalachian Mountains, to the east it is at the west About 2,400 feet of Spechty Kopf rocks underlie the edge of the Pocono Plateau, to the west it lies in the southern part of Broad Mountain, but only about 450 contorted outcrop belt of the Middle Devonian rocks, and to the south it is in the outcrop of the Tuscarora to 500 feet of the lower part of these rocks is preserved Sandstone. in the core of the complex anticlinal and synclinal Other than the great depression, the principal struc­ feature at Rattling Creek. This thickening indicates tural elements of the area are the Broad Mountain and that an Acadian syncline underlies the ?,rea between New Bloomfield anticlinoria and the Minersville syn- Rattling Creek and Broad Mountain. This syncline and clinorium. Superimposed upon these structural elements the anticlinal feautre in Rattling Creek gorge are sub- STRUCTURE 85 stantiated on the isopach map of the Spechty Kopf (fig. Individual folds range in length from less than 1 28). inch to about 27 miles and range in amplitude from a Two other Acadian folds can be inferred from thick­ fraction of an inch to about 16,000 feet. None extend ness variations of the Spechty Kopf Member. An anti­ across the full width of the area from west to east; but cline seems to have formed in Northumberland County several cross two to three quadrangles, and many cross at the approximate position of the crest of the modern a single quadrangle. Broad Mountain anticlinorium (GQ-692,699,700). The Typically, the folds of the area are doubly plunging, postuated crest and trend of this Acadian anticline are but because of the regional northeast plunge, more folds depicted on figure 28 by the elongate area where the terminate in that direction than to the southwest. All member is absent. In addition, a syncline south of this folds, however, die out eventually to the southwest, anticline seems to have formed in Dauphin and central whether in the area or west of it. Schuylkill Counties. The anticlines and synclines that formed during Acadian anticline and synclines seem to have had the Appalachian orogeny trend N. 55° E. to N. 85° E. nearly the same trend as those formed later during the and generally plunge northeast at 4° to 8°. Locally, Appalachian orogeny. This similarity in trend probably where folds are dying out, however, the plunge may means that some Acadian folds have not been identified. be as great as 30° NE. or 30° SW. The rate of regional The modern Broad Mountain anticlinorium and Berry northeast plunge and the maximum rate of plunge near Mountain anticline appear to be rejuvenated Acadian fold terminations were determined from extensive mine folds. Although other modern folds may also have been and field data. rejuvenated, definite evidence is lacking. Most large anticlines north of the Branchdale anti­ Faults that formed during the Acadian orogeny have cline (GQ-690) are simple open folds with broad crystal not been identified, but some of the faults that are con­ areas; in contrast, most large synclines are acute or tight fined to pre-Pocono rocks may originated during this folds. In their midparts the larger synclines generally orogeny. are V-shaped in cross section, whereas near their termi­ nations they are U-shaped. This change from V- to STRUCTURAL FEATURES FORMED DURING THE U-shaped cross sections does not seem to bo related to APPALACHIAN OROGENY rock competency. Locally, where anticlines and syn­ Many thousands of folds and faults were formed in clines are closely spaced and smaller, the anticlines com­ the area during the late Paleozoic Appalachian orogeny. monly are tightly folded but less so than the adjr^-ent Only the larger of these are shown on the quadrangle, synclines. Southeast of the Branchdale anticline and coal, and tectonic maps and the structure sections (GQ- northwest of the Sweet Arrow fault zone (GQ-689), all 689, 690, 691, 692, 698, 699,700, 701; Wood and Trexler, folds are tight, many are broken by high-angle reverse 1968b, c). faults that truncate the crests and troughs, and nany The principal structural features formed during the have overturned limbs. Appalachian orogeny were two anticlinoria a,nd a syn- Parallel folding is the principal style of fold defor­ clinorium. Superimposed upon these complex fold sys­ mation. Mining data indicate that many folds approach tems are a multitude of low-angle, high-angle reverse, parallelism so closely that their shapes, as illustrated underthrust, tear, and bedding-plane faults. on the structure sections (GQ-689, 690, 6'92; Wood and Trexler, 1968c), could have been reconstructed mechan­ FOLDS ically with little error. Most folds die out at depth and show little stratigraphic thinning on their limbs, fome The largest structural features in the area from south larger synclines locally are similar folds that exhibit to north are: the south, or main, trough of the Miners- pronounced thickening in their troughs and thinnir g on ville synclinorium, the New Bloomfield anticlinorium, their limbs. Many folds, even though nearly parallel, the north trough of the Minersville synclinorium, and are locally disharmonic. Disharmonic relations af r>ear the Broad Mountain anticlinorium. Each of these com­ invariably to be associated with incompetent sequences plex fold systems is composed of many en echelon sub­ of shale or coal and are most common in the troughs or sidiary folds which trend east-northeast. The crests and on the lower limbs of synclines. troughs of subsidiary folds large enough to depict at scales of 1:12,000 and 1:24,000 are shown on the maps BROAD MOUNTAIN ANTICLINORIUM and structure sections (GQ-689, 690, 691, 692, 698, 699, The Broad Mountain anticlinorium is one of the 700, 701; Wood and Trexler, 1968b, c). Many hundreds largest structural features in the area. To the soutl west of other folds too small to be shown are present both at it extends at least as far as the Maryland-Pennsylvania the surface and in the subsurface. boundary, and to the northeast it dies out against the 86 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA Pocono Plateau. It trends N. 65° to 80° E. across the 6° to 6%° or about 600 feet per mile. The amplitude of central and northern parts of the Klingerstown, Valley the anticlinorium as measured on the base of the Mauch View, and Tremont quadrangles (pi. 4; GQ-692, 699, Chunk Formation ranges from 13,000 to 18,000 feet in 700). The crest of the anticlinorium in the Klingers­ the western part of the area and is about 1C ,000 feet in town and western Valley View quadrangles is the Hoof- the eastern part. lander Mountain anticline, and in the eastern Valley View and Tremont quadrangles it is the Frackville NEW BLOOMFIELD ANTICLINORIUM anticline. The New Bloomfield anticlinorium is one of the The principal subsidiary anticlines and synclines of larger structural features in the area. It trends N. 60° the Broad Mountain anticlinorium are the Locust to 75° E. across the southern part of the Lykens quad­ Mountain, Mahanoy Creek, North Hooflander Moun­ rangle, the central part of the Tower City quadrangle, tain, Eisenhuth Run, Powder Hill, Hans Yost, Mine and the northern part of the Pine Grove quadrangle and Hill, West West Falls, Peaked Mountain, Crystal Run, plunges out near Tremont in the southeastern part of and Swatara anticlines and the Mahanoy Basin, the Tremont quadrangle (GQ-691, 692, 6P8, 701). It Hooflander Mountain, New Boston, Beury, Jugular, extends many miles southwest of the area to the vicinity Heckscherville, Little Mountain, North Little Moun­ of New Bloomfield, for which it was nam°-d (Miller, tain, Deep Creek, Dam, and Forestville synclines. Each J.T.,1961,p.35). of these anticlines and synclines is several miles long The crestal fold of the anticlinorium in the area is and has a maximum amplitude of several thousand feet. the Joliet anticline. This anticline dies out west of the Outcrops of the axial sections of the subsidiary folds area where the crestal fold is the Berry Mountain anti­ of the Broad Mountain anticlinorium are uncommon. cline. Subsidiary folds of this anticlinorium are less However, the axis of the Jugular syncline is well numerous than they are on the Broad Mountain anti­ exposed in strip pits on the Lykens Valley Nos. 4 and clinorium. The principal folds are the Weft Big Lick 5 coal beds near the Hans Yost and Dyer Run faults in Mountain, Georges Head, and East Georges Head anti­ the northeastern part of the Tremont quadrangle (GQ- clines and the western part of Big Lick Mountain anti­ 692). The axis of the Heckscherville syncline is also cline and Rattling Creek, Tremont, and Lorberry syn­ well exposed in strip pits on several coal beds west of clines. Each of these folds is several miles long and has Mount Pleasant in the Minersville quadrangle (GQ- an amplitude ranging from 0 to 1,000 feet o^* more. 690). The axes of the Powder Hill anticline and Beury The axis of the Joliet anticline is well exposed in syncline are poorly exposed in the canyon of Dyer Run Rausch Creek and in numerous strip pits between this in the same quadrangle. Several strip pits on the Buck creek and the point where the fold terminates near Mountain (No. 5) and Seven Foot (No. 6) coal beds Tremont (GQ-691). Axial sections of the subsidiary have exposed the axis of the Dam syncline in the eastern folds of the anticlinorium are also relatively common. part of the Tremont quadrangle. In addition, the axes The axes of the Rattling Creek syncline and Berry of the Forestville syncline and Swatara anticline are Mountain anticline are well exposed south of Lykens exposed in the canyon of Swatara Creek and in strip in the canyon of Rattling Creek (GQ-701). In addition, pits on the Buck Mountain, Bottom Split (No. 8), and the axes of the Tremont syncline and Big Lick Moun­ Middle Split (No. Sy2) coal beds in the western part tain anticline are well exposed in many strip pits in the of the Minersville quadrangle. The axis of the Crystal Tower City (GQ-698), Pine Grove (GQ-69:.), and Tre­ Run anticline is well exposed in the canyon of Crystal mont quadrangles. Other strip pits have exposed the Run north of Forestville (GQ-690). axes of the Lorberry syncline, Georges Head anticline, The dips of the flanks of the Broad Mountain anti­ and East Georges Head anticline in the Tower City clinorium are usually less than 45° near the crest. Lower and Pine Grove quadrangles. on the flanks where subsidiary folds are common, how­ ever, dips probably average about 50° to 60° and may Dips of the flanks of the New BloomfieH anticlino­ be as steep as 90°. rium commonly are between 20° and 60°, but locally, Rocks as old as the Keyser Limestone of Silurian and are nearly horizontal and in some places are overturned. Devonian age and as young as the Pocono Forma­ The oldest rocks exposed in the crest of the New tion of Early Mississippian age crop out along the crest Bloomfield anticlmorium are in the Honesdale Sand­ of Broad Mountain anticlinorium, whereas on the stone Member of the Catskill Formation of Late Devo­ flanks, the rocks are as young as the Middle and Upper nian age, and the youngest are in the Llewellyn Forma­ Pennsylvanian Llewellyn Formation. tion of Middle and Late Pennsylvanian age. The inten­ The crestal folds of the Broad Mountain anti­ sity of deformation seems to increase strati graphically clinorium plunge east-northeast at an average rate of upwards and eastward on the crest and flanks of the STRUCTURE 87 anticlinorium, and the folding is most complex where folds is several miles long and has an amplitude mms- the Joliet anticline dies out. ureable in hundreds or thousands of feet. The crestal and subsidiary folds of the anticlinorium Only a few axes of the subsidiary folds of the Miners­ plunge northeastward at 9° to 16° or at a rate of 850 to ville synclinorium are exposed. The axis of the Firher 1,500 feet per mile. The structural relief of the anti­ syncline is visible in several strip pits on the Bottom clinorium as measured on the base of the Pottsville Split (No. 8) and Middle Split (No. 8i/2 ) coal bed- in Formation ranges from 0 feet where the Joliet anticline the western part of the Minersville quadrangle (GQ- dies out near Tremont to about 12,000 feet in the south­ 690). The axis of the Branchdale anticline has been ex­ western part of the Lykens quadrangle. posed in several strip pits on the Peach Mountain (No. East of the termination of.the Joliet anticline (pi. 4; 18) and Tunnel (No. 19) coal beds in the vicinity of GQ-692), the New Bloomfield anticlinorium loses its Branchdale in the Minersville quadrangle. In addition, identity as it merges into the broad downwarp of the the axes of the Fisher syncline and Middle Creek anti­ Minersville synclinorium. Thus, the anticlinorium cline are exposed in the gorge of Swatara Creek r°,ar rises westward out of the medial part of the Minersville Zerbe. synclinorium, splitting that structural feature into a North of the north trough of the Minersville synclino­ north and south part. As it rises, subsidiary folds form rium, the flanks of the subsidiary folds generally dip on its flank in a complex structural pattern. about 45°, but locally may be vertical. South of this

MINERSVILLE SYNCLINORIUM trough, the flanks of the folds are commonly over­ turned northward as much as 50°-60°. The Minersville synclinorium probably is the most The south limb of the south or main trough of the important structural feature in the area. East of Tre­ Minersville synclinorium is overturned at most local­ mont (GQ-692) it consists of a complexly folded gen­ ities. This limb embraces 15,000± feet of rocks ranging erally downwarped area whose broad trough area in age from Late Devonian (Trimmers Eock Sand­ trends N. 50° to 60° E. West of Tremont, the broad stone) to Middle and Late Pennsylvanian (Llewellyn downwarped area is split by the eastward-plunging New Formation). Structurally, the limb is bordered to the Bloomfield anticlinorium. The northern split trends north by the trough of the Dauphin syncline and the S. 80° W. from near Tremont to the west border of the Blackwood and to the south by the S^eet area near Lykens (GQ-701) and is here named the north Arrow fault zone. At most places the rocks of this trough of the Minersville synclinorium. The southern limb dip 60° to 89° S. overturned, but locally they dip split trends S. 50° to 60° W. from near Tremont to the as much as 30° S. overturned, are vertical, or dip southwest corner of the Tower City quadrangle (GQ- slightly north. 699) and is here named the south trough of the Miners­ At most places the Llewellyn Formation is expose! in ville synclinorium. the axial part of the Minersville synclinorium, but The main trough and its southwestward continuation, northwest of Lykens the upper part of the Pottsville the south troug'h of the synclinorium, extends about 40 Formation occupies the axial part of the North trough. miles southwest of the area to near Blaserville and a similar distance northwest of the area to near Jim Regionally, the troughs of the Minersville synclino­ Thorpe. Within the area this trough of the synclino­ rium plunge gently northeast at 1° to 3°. The amplitude rium is everywhere the axis of the Dauphin syncline. of the main, or south, trough is unknown because the East of Baird Eun in the Pine Grove quadrangle (GQ- south limb of the synclinorium is overturned and may 691), it is overlain by the upper plate of the Black- be the limb of a nappe that before modern erosion st^uc- wood thrust fault. turally overlay the trough and north limb, but the The north trough of the Minersville synclinorium 15,000± feet of overturned rocks exposed on the scnth extends about 80 miles west of the area, where it termi­ limb indicates the minimum amplitude. nates in the vicinity of Fort London. In the area, the The structural relief on the base of the Pottsville For­ north trough is the Donaldson syncline from the vicinity mation between the south trough of the synclinorium of Tremont to the vicinity of Lykens. Farther west to and the crest of the New Bloomfield anticlinorium the border of the area, Shiro syncline occupies the ranges from 0 to 12,000 feet. The amplitude of the north trough. trough, also on the Pottsville Formation, ranges from The principal subsidiary folds of the Minersville syn­ 13,000 to 18,000 feet. clinorium are the New Mines, Phoenix Park, Middle ANTICLINES Creek, Big Lick Mountain, Branchdale, Georges Head, Many hundreds of anticlines and associated syncl;nes and East Georges Head anticlines and Phoenix Park, are present in the area. Only the larger of the anticFnes Tremont, Fisher, and Llewellyn synclines. Each of these are shown on the maps and sections (pi. 14; GQ-689, GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA

690, 691, 692, 698, 699, TOO, 701; Wood and Trexler, limb, in contrast to the en echelon Hooflander Mountain 1968b, c), and only the largest or structurally more anticline with its steeper south limb. The amplitude of important of these are described. the Frackville anticline on the base of the Focono For­ mation ranges from about 6,000 feet in the northeastern HOOFLANDER MOUNTAIN ANTICLINE part of the area to about 12,000 feet in the north-central The easternmost 13 miles of Hooflander Mountain part. anticline lies in the area and strikes about N. 80° E. WEST WEST FALLS ANTICLINE across the central part of the Klingerstown quadrangle The West West Falls anticline trends N. 80° to 85° E. and the west-central part of the Valley View quad­ for about 19 miles from the west border of the northern rangle, where it is the crestal fold of the Broad Moun­ part of the Lykens quadrangle (GQ-701) to the east- tain anticlinorium (GQ-699-700). Near its eastern central part of the Tremont quadrangle (GQ-692) termination, it splits into two anticlines and an inter­ where it divides into the Crystal Run anticline, Forest- vening syncline. This furcation takes place in the incom­ ville syncline, and Swatara anticline. These three folds petent upper shale member of the Mahantango in the east half of the Minersville quadrangle (GQ- Formation and appears to be the result of disharmonic 690) become a part of the complexly deformed north folding of shale above a single parallel fold in the limb of the Minersville synclinorium. The locality competent Montebello Sandstone Member of the Mahan­ where the West West Falls anticline splits has been tango Formation. rather well exposed by erosion, strip mining, and under­ Rocks ranging in age from Silurian (lower part of ground mining. The reason for splitting if not under­ Keyser Limestone) to Late Devonian (Trimmers Rock stood, but the incompetent beds of the Mp.uch Chunk Sandstone) crop out on the crest of the Hooflander Formation were flexed into a single anticline, whereas Mountain anticline, and rocks as young as the Mauch the overlying more competent beds of th^ Pottsville Chunk Formation are exposed on the limbs. The dips on Formation and the less competent beds of the Llewellyn the limbs range from about 1° to 75° and average about Formation were flexed into a compound fold system 40°. The anticline is asymmetric, and the south limb whose structural relief decreases eastward and strati- is generally slightly steeper than the north limb. The graphically upward into the generally c'ownwarped amplitude of the anticline on the base of the Irish Val­ north limb of the Minersville synclinorium. ley Member of the 'Catskill Formation at the west border of the area is about 16,000 feet. The West West Falls anticline is the southernmost of the large upwarp structure lying between the crest of FRACKVILLE ANTICLINE the Broad Mountain anticlinorium and the north trough The Frackville anticline trends N. 65° to 80° E. from of the Minersville synclinorium. Rocks of the Mauch the eastern part of Lykens quadrangle (GQ-701) to Chunk, Pottsville, and Llewellyn Formations crop out the northeast corner of Tremont quadrangle (GQ-692). on the crest and limbs. The dips of the limbs range from Its extent in the area is about 17 miles. Throughout all about 1° to 80° and average about 45°. The fold is asym­ but the westernmost 5 miles, it is the crestal fold of the metric ; the south limb generally is slightly steeper than Broad Mountain anticlinorium and is generally the the north limb. The amplitude of the anticline on the principal structural feature separating the Southern base of the Mauch Chunk Formation see^s to range and Western Middle Anthracite fields. It is en echelon from 0 feet to about 6,000 feet and averages about 3,500 with the Hooflander Mountain anticline to the west and feet. is separated from that fold by a shallow syncline. The BEANCHDALE ANTICLINE two anticlines plunge in opposite directions and prob­ The Branchdale anticline is about 6 miles long. It ably formed as pressures were transferred from one trends N. 60° to 80° E. from Newtown in the western part weak zone to another during deformation. of the Minersville quadrangle (GQ-690) to the east bor­ Rocks that range in age from Late Devonian (Trim­ der of the area. The north limb is overturned from near mers Rock Sandstone) to Early Mississippian (Pocono Steins to the east border. The anticline is the northern­ Formation) crop out on the crest of the Frackville most fold of a group in which the north limb of each fold anticline, and rocks as young at Late Pennsylvanian is overturned for a considerable distance. T' is overturn­ (upper part of Llewellyn Formation) crop out on the ing approximately demarcates the boundary between flanks. open folds to the north and tight folds to the south. The limbs of Frackville anticline dip from about 1° The Branchdale anticline is strongly asymmetric; to 70° and average about 30°. The north limb of the rocks on the upright south limb dip an average of 35° anticline is generally somewhat steeper than the south S., whereas rocks on the north limb are overturned and STRUCTURE 89

have dips as low as 57° S. Thus, rocks on the north limb JOLIET ANTICLINE have been rotated as much as 158° beyond the 35° The Joliet anticline is about 20 miles long and trends average dip of the south limb. The anticline has an N. 55° to 75° E. from the south border of the Lykens average amplitude of about 1,000 feet on the Primrose quadrangle to the southeast corner of the Tremont quad­ (No. 11) coal bed. Crestal sections are well exposed in rangle. It is the crestal fold of the New Bloomfield anti- strip pits on the Peach Mountain (No. 18) and Tunnel clinorium and is the largest anticline in the southwestern (No. 19) coal beds near Branchdale (Wood and Trexler, part of the area. The amplitude on the base of the Potts- 1968b, sheet 2). ville Formation ranges from 0 feet near Tremont to BIG LICK MOUNTAIN ANTICLINE about 12,000 feet in the southwestern part of the Lykens The Big Lick Mountain anticline is about 11 miles quadrangle. long and trends N. 60° to 75° E. from the northeastern West of Lower Rausch Creek (GQ-691, 698, 701) part of the Tower City quadrangle (GQ-698) to where the Joliet anticline is a broad relatively symmetrical it terminates against the Newtown fault in the south- flexure, but to the east, it gradually becomes sharper central part of the. Minersville quadrangle (GQ-690). and asymmetrical, the north limb being slightly steeper. Locally, between Tremont and Donalclson (GQ-692) The dips of both limbs range from about 1° to 70° r,nd and near Newtown the north limb is overturned. Its dips average about 30°. Crestal sections are well exposed in range from 75° N. to 80° S. overturned, whereas the dips the valley of Lower Rausch Creek and in strip pits a of the upright south limb range from 50° to 60° S. The short distance to the east on the Bottom Split (No. 8), anticline is strongly asymmetric to the north and plunges Middle Split (No. 8y2 ), Holmes (No. 10), and Primrose east-northeast. Its amplitude averages about 1,000 feet (No. 11) coal beds (Wood and Trexler, 1968b, sheet 4). on the Primrose (No. 11) coal bed. Sections of the limbs Between Joliet and Lower Rausch Creek the axis is well and crest are well exposed in many strip pits in the known in the subsurface because of mining on the Tower City, Pine Grove, Tremont, and Minersville Lykens Valley Nos. 1-4 coal beds. quadrangles (Wood and Trexler, 1968b, sheets 2-4; 1968c, sheet 1). ROEDERSVILLE ANTICLINE The Newtown fault and Big Lick Mountain anticline The Roedersville anticline is the southernmost large separate major structural provinces (provinces 3 and 4, upwarp in the area. It trends about N. 75° E. for nearly Amdt and Wood, 1960, p. B183) in the Minersville 8 miles across the eastern part of the Pine Grove ?,nd quadrangle (GQ-690). North of this fold and fault the Swatara Hill quadrangles (GQ-691, 689). The fold is Minersville synclinorium is characterized by upright not well exposed, but structural attitudes and the strati- folds, numerous short high-angle reverse faults, and graphic succession prove its existence. low-angle folded thrust faults. In contrast, to the south, Rocks as old as Late Silurian (Bloomsburg Fed the synclinorium is characterized by few complete folds, Beds) and as young as Late Devonian (Trimmers Rock by numerous long high-angle reverse faults, by an ap­ Sandstone) crop out on the crest and flanks of the parent lack of low-angle folded thrust faults, and by Roedersville anticline. The structural relief of the anti­ alternating fault-bounded belts of upright and over­ cline in the upper plate of the Sweet Arrow fault zone turned rocks. A short distance west of the Minersville averages about 1,500 feet. quadrangle, the boundary between structural provinces The Roedersville anticline, Sweet Arrow fault zcne, 3 and 4 leaves the crest of the Big Lick Mountain anti­ Blackwood fault, the overturned south limb of the cline, trends southwestward across several minor folds Dauphin syncline, 'and the Pine Grove syncline proba­ and faults that underlie the borough of Tremont, and bly formed at approximately the same time. As shown intersects the trough of Llewellyn syncline (pi. 4; GQ- on the structure sections (GQ-689, 691), a part of 692; Wood and Trexler, 1968b, sheet 3). The boundary the Roedersville anticline is believed to lie in the snb- follows this trough westward to Lower Rausch Creek mrface in the lower plate of the Sweet Arrow fault (Wood and Trexler, 1968b, sheet 4). At the latter point, zone about 1 mile south of the trace of the zone. The the boundary is arbitrarily placed along Lower Rausch placement of a part of the anticline in the upper plate Creek transverse to the structural grain to where the and a part in the lower plate of the Sweet Arrow fault creek intersects the Blackwood fault. It then follows zone probably formed as follows. During the Apna- Blackwood fault westward to the trough of the Dauphin Lachian orogeny, the area between the present troi^gh syncline. West of the intersection of the Dauphin syn­ of the Minersville synclinorium and Blue Mountain cline and Blackwood fault, the boundary follows the was subjected to gradually increasing deformation. trough of the syncline (pi. 4; GQ-692; Wood and Trex­ The Roedersville upwarp, flanked to the north by the ler, 1968b, sheet 4; 1968c, sheets 1, 2). Dauphin downwarp, formed gradually. The limb be- 90 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA tweeii the anticline and syncline was uplifted gradually the structure sections (Wood and Trexler, 1968b, and oversteepen. to the north. During the oversteepen- sheet 5, sections A-E]. ing, the major low-angle Blackwood thrust fault cross­ Underground in the Thomaston mine near Heck­ cut the limb, the trough of the syncline, the crest of the seherville, the trough of the syncline has b°«n dishar- anticline, and the south limb of the anticline. The monically folded into two synclines and an anticline trough of the syncline deepened as compression and (Wood and Trexler, 1968b, sheet 5, section B). The faulting continued. The anticline grew in amplitude, disharmonic relations seem to have been caused by and the plane of the fault was warped gently over the differential bedding-plane slippage betweer coal, shale, crest of the anticline. Movement on the fault, therefore, and sandstone sequences. Locally, the thickness of coal was impeded, and the deforming forces sought release beds and intervening rocks have been increased several through the northward-spooning low-angle Sweet times by the differential slippage. Arrow fault zone which formed at the crest and on the south limb of the Roedersville anticline. As the fault LITTLE MOUNTAIN SYNCLINE zone formed, rocks in the upper plate slid northwest­ The Little Mountain syncline trends N. 55° to 70° ward from their original position on the crest and E. for about 5 miles from the central part of the Tre- south limb of the Roedersville anticline to their present mont quadrangle to the west-central part of the position above the overturned rocks of the common Minersville quadrangle (GQ-692, 690; Wood and limb of the anticline and Dauphin syncline in the lower Trexler, 1968b, sheets 1-3). The Heckseherville syn­ plate. cline is en echelon with the Little Mountain syncline SYNCLINES to the east. Mine workings indicate that as the Heck­ Many synclines are present in the area, but only the seherville syncline dies westward, Little Mountain larger are shown on the maps and sections (pi. 4; syncline dies eastward. The forces causing deforma­ GQ-689, 690, 691, 692, 698, 699, TOO, 701; Wood and tion apparently were transferred betweent the two Trexler, 1968b, c). In addition, only the larger or struc­ major folds across two minor intervening anticlines and turally more important of these are described. a syncline. Rocks on the limbs of Little Mountain syncline dip HEOKSCHERVILLE SYNCLINE from about 10° to 80°. The amplitude of the fold on the The Heckseherville syncline trends N. 75° E. for Buck Mountain coal bed ranges from 0 feet at its about 6 miles from a point about 3 miles west of Buck terminations to 2,500 feet in its midpart. Strata from Run in the Minersville quadrangle to the east border the middle part of the Tumbling Run Member of the of the area. It is the northernmost heavily mined syn­ Pottsville Formation to the Top Split (No. 9) coal cline in the west-central part of the Southern Anthra­ bed of the Llewellyn Formation crop out ir the trough cite field. of the syncline, and rocks of the middle member of the Rocks of the Pottsville and Llewellyn Formations Mauch Chunk Formation are intermittently and poorly crop out on the limbs and in the trough of the syncline, exposed on the limbs. Axial sections are exposed in both of which have been exposed at many places, partic­ several strip pits along the fold. ularly west of Mount Pleasant in strip pits on the The Little Mountain syncline plunges eastward at 2° Bottom Split (No. 8), Top Split (No. 9), Holmes to 4°. Near the common border of the Tremont and (No. 10), and Primrose (No. 11) coal beds (Wood and Minersville quadrangles, it is linked structurally to the Trexler, 1968b, sheet 1). The axis and limbs are also Peaked Mountain anticline by a subsidiary anticline well known in the subsurface from workings of the and syncline. The linking folds plunge westward in the Glendower, Thomaston, Payne, and Pine Knot mines. opposite direction from the plunge of the major folds. The amplitude of the Heckseherville syncline aver­ NORTH LITTLE MOUNTAIN SYNCLINE ages about 2,000 feet, and the geometry of the fold is probably better known than that of any other syn­ The North Little Mountain syncline trends N. 60° to cline in the area. Dips on the limbs range from about 80° E. from the east-central Valley View quadrangle 10° to 70° and average about 50°. Mining data indi­ (GQ-699) to the south-central Tremont quadrangle cate that the syncline is nearly symmetrical and that it (GQ-692). It is en echelon with the Little Mountain plunges gently east at 1° to 5°. The geometric con­ syncline to the east and the Deep Creek syncline to the figuration, the sequence of coal beds, and the relation­ west. It is about 5 miles long and has an amplitude of 0 ship of the syncline to nearby folded low-angle thrust to 2,500 feet on the base of the Pottsville Formation. faults are shown on the quadrangle and coal maps The limbs of the syncline dip from 1° to 50° and aver­ (GQ-690; Wood and Trexler, 1968b, sheet 1) and on age about 40°. STRUCTURE 91 An axial section of the North Little Mountain syncline in the northeastern part of the Tower City quadrangle is exposed where the paved road between Hegins and several miles east of Rausch Creek Gap, where an axial Weishample crosses Little Mountain. Rocks as old as section is exposed in a strip pit on the Tracy (No. 16) the middle member of the Mauch Chunk Formation and coal bed (Wood and Trexler, 1968c, sheet 1). Many as young as the Tumbling Run Member of the Potts­ hundreds of manmade and natural outcrops are pr°£- ville Formation crop out in the trough and on the limbs ent on the limbs. The trough generally has been eroded of the syncline. into a series of valleys and is surfaced by rocks of the DEEP CREEK SYNCLINE Llewellyn Formation, except in the westernmost 1 mile where rocks of the Pottsville Formation crop out (GQ- The Deep Creek syncline is about 13 miles long and 701; Wood and Trexler, 1968c, sheet 3). The limbs are trends N. 60° to 85° E. from the west border of the Klingerstown quadrangle (GQ-700) to the southeastern composed of rocks ranging stratigraphically from the middle member of the Mauch Chunk Formation to the part of the Valley View quadrangle (GQ-699). It is en 23% coal bed of the Llewellyn Formation. echelon with the North Little Mountain syncline. This West of the John Veith shafts in the central part of latter fold is en echelon with the Little Mountain the Minersville quadrangle (Wood and Trexler, 1968b, syncline, which is, in turn, en echelon with the Heck- sheet 2), Donaldson syncline is generally an isoclinal scherville syncline. The Deep Creek-Heckscherville syn- fold. To the east it is asymmetrical, and its south limb is clines and the Shiro-Donaldson synclines are the only overturned. This limb is also overturned near Donald- fold systems that extend completely across the area from son in the Tremont quadrangle (GQ-692). The dip of west to east. the north limb ranges from about 10° to 70° S. and av­ The middle member of the Mauch Chunk Formation erages about 45°; the dip of the south limb ranges from is at the surface throughout the length of the Deep Creek about 5° N. to 57° S. overturned. syncline. Rocks of this member are relatively soft and The Donaldson syncline is the deepest downwarp in easily eroded. As a result, the syncline underlies a wide the area, with the exception of the Dauphin syncline. valley, in contrast to most other synclines in the area. Its amplitude on the Buck Mountain (No. 5) coal bed The Deep Creek syncline is one of the more tightly ranges from 0 feet at its west termination to about 7,POO folded flexures north of the Minersville synclinorium. Its limbs and trough have been wrinkled into many feet at the east border of the Lykens quadrangle (GQ- 701). It maintains an amplitude of 4,000 to 7,800 feet subsidiary folds, some of which are large enough to be shown on maps and structure sections (pi. 4; GQ-699, between the east border of the Lykens quadrangle and Donaldson in the Tremont quadrangle (GQ-692). East 700). The trough of the Deep Creek syncline is not well ex­ of the Donaldson, the amplitude decreases rapidly to less than 1,000 feet over most of the Minersville qur 4- posed at any locality, but the existence of the fold is authenticated by numerous outcrops on the limbs. Dips rangle (GQ-690) and is about 700 feet at the east at these outcrops range from 10° to 80° and average border of the area. The near-surface configuration of Donaldson syncline about 20°. The amplitude of the syncline on the base of the Mauch Chunk Formation seems to range from 0 feet is rather well known from much strip and underground to about 2,500 feet and to average about 2,000 feet. mining. At depth, however, the axis has not been crossed by mining at any locality. The configuration at depth, DONALDSON SYNCLINE therefore, has been extrapolated from near-surface dr.ta The Donaldson syncline trends N. 65° to east-west on the limbs and in the axial area (Wood and Trexler, for about 27 miles from the northwestern part of the 1968b, sheets 5, 6, sections B-P\ 1968c, sheet 4, sections Lykens quadrangle to the east-central border of (pi. A-P). 4; GQ-690, 691, 692, 698, 701; Wood and Trexler, TREMONT SYNCLINE 1968b, c) Minersville quadrangle and extends an un­ The Tremont syncline trends N. 75° to 85° E. for about known distance east of the area. It is the north trough 12 miles from the north-central part of Tower City quad­ of the Minersville synclinorium between the northwest­ rangle (GQ-698) to the southwestern part of the ern part of the Lykens quadrangle and the southeastern Minersville quadrangle (GQ-690). It terminates to the part of the Tremont quadrangle. East of the Tremont west on the south slope of Big Lick Mountain and is quadrangle, the Donaldson syncline and the north truncated to the east by the South Newtown fault. Rocks trough merge imperceptibly into the series of folds on of the Pottsville Formation crop out along the axis in the north limb of the main trough of the synclinorium the western 2 miles, and those of the Llewellyn Forma­ as the structural relief is reduced gradually. tion crop out in the eastern 10 miles. The axis of the Donaldson syncline is visible only The axis and limbs of the Tremont syncline are 316-352 O 69 7 92 GEOLOGY, SOUTHERN AJSTTHRiACITE FIELD, PENNSYLVANIA exposed at many places in the Tower City quadrangle Middle Devonian (Mahantango Formation) to Late (Wood and Trexler, 1968c, sheet 1) where coal beds Pennsylvanian (upper part of Llewellyn Formation in from the Skiclmore (No. 7) to the Orchard (No. 12) part) form the limbs. The axis is everywhere concealed have been extensively strip and underground mined. but numerous strip pits and extensive underground mine The limbs crop out in many strip pits in the Pine Grove workings on the limbs show the near surfa.ce configura­ quadrangle (Wood and Trexler, 1968b, sheet 4) but tion of the syncline and indicate an eastward plunge of rarely are exposed in the Tremont and Minersville 1,4° to 3°. The dip of the north limb range? from 30° to quadrangles (sheets 2, 3). 85° S. and averages about 50° S. At most localities the The subsurface configuration of the western part of south limb is overturned northward, and the dip is 30° the Tremont syncline, like that of the Heckscherville to 89° S. and averages about 75° S.; local^ however, it and Forestville synclines, is well known. Extensive is vertical or inclined steeply north. underground mine workings in the Westwood, Keefer, The amplitude of the Dauphin syncline is unknown Tower City, Porter, and Brookside mines and numer­ because the south limb has been overturned and thrust ous surface outcrops provide structural control that is faulted, but it is at least 15,000 feet in the, eastern part exceptional for the area (Wood and Trexler, 1968c, of the area. The structural relief between the trough sheet 4, sections A-6r). Structure sections A through G and the crest of the adjacent Joliet anticline is about illustrate the westward change of the syncline from a 12,000 feet in the western part of the area (GQ-701). V-shaped fold in the midpart to a U-shaped fold near the The subsurface configuration of the Dauphin syn­ end. cline is illustrated on structure sections (GQ-690, 691, The limbs of the Tremont syncline dip from 8° to 80° 698; Wood and Trexler, 1968b, sheets 5, 6, sections B-P ; and average about 60°. The fold plunges eastward at 3° 1968c, sheet 4, sections A-V) . West of the intersection of to 5°, and the amplitude ranges from 0 feet to about the trough and Blackwood thrust fault, the fold is 5,000 feet and averages about 2,500 feet. asymmetric, the rocks in the south limb Hing slightly The Tremont syncline is the southernmost syncline in overturned northward. East of the intersection, the the coal field whose south limb is not overturned. At its rocks in the upper and lower plates of the fault are eastern termination the trough is truncated by the overturned. Because the rocks in the upper plate South Newtown fault. East of this cutoff, the rocks dip represent a truncated part of the south limb of the south in both fault plates, which suggests that faulting Dauphin syncline which has been displaced northward, replaced folding as the stress-releasing mechanism. it is believed that the syncline is strongly overturned Structure sections (Wood and Trexler, 1968b, sheet 5, beneath the fault. As shown on the structure sections sections E-G) west of the cutoff indicate that tihe syn­ (iGQ-690, 691, 698), the axial plane may approach cline loses amplitude eastward and that the trough recumbency beneath Sharp and Second Mountains. probably did not exist in the upper plate of the fault. PINE GROVE SYNCLINE

DAUPHIN SYNCLINE The Pine Grove syncline is the southernmost large The Dauphin syncline is the most deeply downwarped downwarp north of the Great Valley in the Eidge and and one of the more important synclines in the Anthra­ Valley province. It trends N. 55° to 80° E. for about cite region, although others ,are longer. It forms the 16 miles from the southeast corner of the Tower City south, or main, trough of the Minersville synclinorium quadrangle to the east-central border of the Swatara and extends at least 40 miles southeast of the area, and Hill quadrangle (GQ-689, 691, 698). East of the area, an unknown distance eastward beneath the Blackwood it extends at least 12 miles to the vicinity of New Ring- fault. It strikes N. 50° to 65° E. from the southwestern gold. The trough and north limb are truncated in the part of the Tower City quadrangle to the west-central southeastern part of the Tower City quadrangle by the part of the Pine Grove quadrangle (pi. 4; GQ-691,698; Sweet Arrow fault zone, and the extent of the south Wood and Trexler, 1968b, sheet 4; 1968c, sheet 2). The limb to the southwest is uncertain. trough and south limb are truncated by the Blackwood The trough of Pine Grove syncline is underlain by fault near the junction of West Branch Fishing Creek rocks of the Trimmers Rock Sandstone and Irish Val­ and Baird Run (pi. 4; GQ-691; Wood and Trexler, ley Member of the Catskill Formation. The limbs con­ 1968b, sheet 4). East of this point to the east border tain rocks ranging in age from Early Silurian (Tusca- of the area, the trough lies below the fault plane; the rora Sandstone) to Late Devonian (Irish Valley north limb is continuous, whereas the south limb is Member of the Catskill Formation). The trough line is broken by several large tear faults. more sinuous than that of most other syn-lines, reflect­ The Llewellyn Formation is exposed in the trough ing the comparative flatness of the limbs near the axis. of Dauphin syncline, and rocks ranging in age from Dips near the axis commonly are less than 15° and STRUCTURE 93 rarely exceed 20°, but farther from the axis they range FAULTS from 20° to 65° and generally are about 25°. Numerous thrust, high-angle reverse, underthriM, Axial sections of the Pine Grove syncline are not ex­ bedding-plane, and tear faults fracture the rocks of the posed. Several faults and smaller folds have broken area. Many of these are shown on the maps and sections and wrinkled the syncline limbs. The larger of these are (pi. 4; GQ-689, 690, 691, 692, 698, 699, 700, 701; Wood the Applebee, Suedberg, Swope, and White Horse and Trexler, 1968b, c), but by far the majority are not faults; the Mill and Irving synclines; and the Out- shown because they are too small to depict at scales of wood, Suedberg, and Swope anticlines (GQ-689, 691). 1:12,000 and 1:24,000, or they were not exposed. These 'structural features are believed to be confined The density of mapped faults is greatest in that part to the upper plate of the Sweet Arrow fault zone. of the area underlain by anthracite. Exposures in strip The Pine Grove syncline plunges eastward at 3° to 5°. pits and in the many square miles of underground mine The amplitude is unknown but seems to increase east­ workings have made possible the identification and trac­ ward from a few hundred feet in the Tower City quad­ ing of faults in this part of the area. Elsewhere, the rangle to at least 5,000 feet in the eastern part of the density of mapped faults is appreciably lower. In the Swatara Hill quadrangle. past, this difference in density has been attributed to the Structurally, the Eoedersville anticline and Pine coal-bearing rocks being unusually susceptible to fault­ Grove syncline form an isolated bulb-shaped area of ing but it is probably because the faults can be iderti- apparently slightly deformed upright rocks lying above fied and traced more completely in mine workings. 1\e the Sweet Arrow fault zone and between overturned rocks in the larger natural exposures outside the COT.!- highly deformed rocks of the south limb of the Miners- bearing area generally are cut by a multitude of faults. ville synclinorium (south limb of the Dauphin syncline) Most of these are small, but many that appear to be and the generally overturned and recumbent more high­ large cannot be traced beyond the limits of an outcrop. ly deformed rocks of the Great Valley (see Gray and One of the primary difficulties in fault terminology others, 1960). The bulbous shape of this area is reflected is that faults are arbitrarily termed "high" or "low r,n- by a corresponding northward curvature of the south gle" with eference only to their attitudes at present. limb of the synclinorium and the trace of the Sweet The commonly accepted division between high and low Arrow fault zone and by a southward curvature of the angle is 45° to the horizontal. This arbitrary separation north side of the Great Valley. of faults at 45° is usable and meaningful only if the The presence of an area of upright rocks lying in the faults have not been folded subsequently. In this report, midst of an overturned area is anomalous. It seems therefore, high- and low-angle faults are classified on probable that the Pine Grove syncline and Eoedersville the basis of whether they are believed to have dipped anticline are the uneroded remnants of a lower upright more or less than 45° at the time of faulting. If a fault limb of a nappe or recumbent fold that was moved to is believed to have had an initial dip different from the its present structural position along the Sweet Arrow present dip, reasons are presented for that belief. thrust fault zone. The inverted limb and upper upright Faults that trend parallel or subparallel to the re­ limb of the nappe have been removed by erosion in the gional structural grain, whose hanging wall moved up­ area, but their roots may be represented by overturned wards, and whose attitudes at the time of faulting r,re and upright rocks in the Great Valley to the south. believed to have been less than 45°, are termed "thrusts" The Sweet Arrow fault zone truncates the axis of the in this report. Many thrust faults have been folded, and Pine Grove syncline in the southeastern part of the their original attitudes and structural parallelism have Tower City quadrangle. In the Indiantown quadrangle, been obscured. southeast of this point, the fault zone gradually begins Faults whose hanging walls moved upwards and to truncate overturned rocks of the south limb of the whose attitudes at the time of faulting are believed to syncline or the inverted limb of the nappe. East of the have been more than 45° are termed "high-angle re­ report area the Eoedersville anticline and Pine Grove verse faults." Some have been folded or tilted; but most syncline plunge out near New Einggold. As these folds are not folded, or are at most, slightly warped. terminate, the fault zone truncates the lower upright Faults that trend parallel or subparallel to the re­ limb and gradually cuts into the inverted limb. The gional structural grain and whose footwalls moved up­ lower upright limb of the nappe, or the bulbous area ward are termed "underthrusts," irrespective of their formed by the upright rocks of the anticline and syn­ angle of dip. Underthrusts formed during all stages of cline, is, structurally eliminated southwest and northeast the deformation of the area. Therefore, those tl at of the report area by the Sweet Arrow fault zone cutting formed in the early stages of deformation were folded upward into the inverted limb. in later stages. 94 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA Faults that trend at considerable angles to the regional the folded low-angle faults formed as underthrusts, the structural grain and whose primary movements were lower competent plate moving away from the source of in general parallel to fault traces are termed "tear compression at a faster rate than the upper incompetent faults." The larger tear faults are the terminations of or plate. The incompetent plate generally crumbled into a the imbrications from thrust faults. Near the termina­ series of folds. tion of some thrusts, the strike swings more to the south, PISHEE EIDGE FAULT and the slip gradually shifts from upward, to the north­ The Fisher Ridge fault, the westernmost folded west, on the thrust part to horizontal on the tear part. thrust fault, is on the crest and flanks of the Broad The other tear faults are considerably smaller and are Mountain anticlinorium in the central part of the the result of differential structural adjustments within Klingerstown quadrangle (GQ-700). It sterns to have individual thrust blocks. Most tears dip steeply to the originated in the upper beds of the upper shale member east near the surface, but at depth the dip of the larger of the Mahantango Formation and to have cut upward tears is believed to decrease gradually to nearly hori­ into the basal and medial parts of the Trmmers Eock zontal, as would be expected on combined thrust and Sandstone. The plane of the fault is not exposed, but tear planes. its existence is proven by beds both above and below Faults with planes parallel or nearly parallel to bed­ being truncated and offset along a persistent discord­ ding attitudes of adjacent rocks are termed "bedding- ancy which is traceable on both limbs of the Hoof- plane faults." They seem to have formed during all lander Mountain anticline and across the crest of the stages of deformation and are, therefore, high angle North Hooflander Mountain anticline as well as across and low angle and folded and nonfolded. Their paral­ the trough of the Hooflander Mountain syncline. lelism to bedding and their infrequent exposure makes them difficult to date with reference to other fault types HEGINS FAULT or to attempt to classify their angular relations to the The Hegins fault may not be a single continuous horizontal at the time of faulting. The Short Mountain fault. A fault is exposed at three localities along its hy­ fault is the only bedding-plane fault shown on the pothetical trace: north of Spring Glen in the Valley maps of this report. It is identified as a thrust (GQ-701; View quadrangle (GQ-699), about half '?, mile north­ Wood and Trexler, 1968c, sheet 3) because its plane west of Coleman Church in the Klingerstown quadran­ locally cuts the bedding. Other faults of this type may gle (GQ-700) and about 0.2 mile south of Klingers be present but could not be recognized. School in the Tremont quadrangle (GC-692). Else­ LOW-ANGLE FOLDED THRUST AND UNDERTHRUST FAULTS where, the fault separates structurally discordant strata Low-angle folded thrusts and underthrusts generally or is completely undiscernible between parallel beds are the largest and most complex faults in the area. above and below. Therefore, it has been shown as a Some extend over and through several anticlinal crests doubtful fault throughout most of its length. and synclinal troughs. They are difficult to trace on the The trace of the Hegins fault is sinuous and trends surface because of extensive cover and vegetation, the generally northeastward. It enters the area in the north­ low angle between their planes and truncated strata, west corner of the Lykens quadrangle (GQ-701) and and the general similarity of offset strata at many trends about N. 80° E. for 8 miles to a point where it localities. It is doubtful that most of the mapped folded crosses the northeast-plunging West Wert Falls anti­ faults would have been discerned without substantiat­ cline (GQ-699). On the north flank of the anticline it ing evidence from mine workings. trends nearly due west for slightly more than 7% miles The larger folded faults are confined to the Mahan- to where it crosses the axis of the Deep O^ek syncline tango, Mauch Chunk, and Pottsville Formations, the as a sharp horseshoe bend (GQ-700). Thence, it trends Trimmers Eock Sandstone, and the lower part of the about N. 80° E. on the north flanks of the. Deep Creek, Llewellyn Formation. They are confined to these for­ North Little Mountain, and Little Mountain synclines mations probably because of differences in competency for about 20 miles to the axis of the Hans T7"ost anticline between sequences dominated by sandstone and con­ in the east-central part of the Tremont quadrangle glomerate and sequences dominated by shale and coal. (GQ-692), where its trace reverses sharply to about In many localities where competent rocks overlay in­ N. 80° W. for about 1 mile to the axis of the Jugular competent rocks, the folded low-angle faults formed as syncline (GQ-692). After folding around this axis, it thrusts on which the upper more competent plate tore continues a sinuous trend of N. 30° E. for about 4 miles loose from the more incompetent lower plate and over­ to the northeast corner of the Tremont quadrangle rode it for varying distances. Elsewhere in those locali­ (GQ-692), where it joins the underlying Mauchono ties where incompetent rocks overlay competent rocks, fault. STRUCTURE 95 The entire trace of the Hegins fault is in the middle of the lower plate has a stratigraphic range of at least member of the Mauch Chunk Formation and generally 2,000 feet. separates older strata above from younger strata below. At most places the Hegins fault is believed to cut the In the three places where the fault is exposed, drag bedding at an angle of 10° to 20° (GQ-690,692, 698,699, folds, slickensides, offset beds, and overturned beds 701, structure sections), but locally, as in the trougl of were observed. Elsewhere, mappable sequences in the the Deep Creek syncline, the angle appears to be. as formation that consist largely of shale or sandstone have great as 45° (GQ-700, structure sections). been truncated both at the top of the lower plate and the Genetically, the Hegins fault appears to be a low- base of the upper plate. angle or slightly discordant bedding-plane thrust that From its northeast end across the Tremont quad­ passes into the subsurface to the southeast where its rangle and almost-to the west side of the Valley View exact nature is concealed. The fact that the west and quadrangle, the Hegins fault lies at or near the base of central parts of the fault trend from N. 80° E. to e^st- red sandstone sequence B (GQ-690, 699) in the upper west, generally pass beneath the surface to the south- plate and several hundred feet above the same sequence southeast, and generally rise above the surface to the in the lower plate. Between the west side of the Valley north-northwest suggests that the upper plate of the View quadrangle and a point near where the fault fault along these parts of the fault moved chiefly north­ crosses the Deep Creek syiicline (GQ-700) it separates ward. However, the upper plate along the eastern part strata several hundred feet above red sandstone unit B of the fault (GQ-692) may have moved more to the in the lower plate from strata of an older sandstone, west because that part of the fault trends about N. 20° unit C, in the upper plate, except for a short distance E. and generally passes into the subsurface to the east- in the southeast corner of the Klingerstown quadrangle southeast. where the fault rises stratigraphically into sandstone The junctioning of the Hegins and Mauchono faults sequence B in the upper plate. From a point on the in the northeast corner of the Tremont quadrar

316-352 O - 69 - 8 108 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSTILV1ANIA Mine records of the Short Mountain, Williamstown, cates that the Applebee is a north-dipping high-angle and Gratz mines show that the combined displacement reverse fault whose southward stratigraphic displace­ of the faults of the Coal Mountain complex ranges from ment may have been as great as 600 feet (GQ-689, and 0 to about 2i,100 feet and that the displacements of North 691, structure sections) . and South Coal Mountain faults reach maximums of 500 and 1,000 feet, respectively. Eecords also show that WHITE HOUSE AND BOUND HEAD the displacement of the complex increases gradually The White Horse and Round Head faults extend westward, reaches a maximum near Short Mountain from the south-central part of the Sw^tara Hill tunnel, and then dies rapidly westward (Wood and quadrangle to the east border of the area (GQ-689), Trexler, 1968c, sheets 3, 4). following the upper south slope of Blue Mountain, The age of the Coal Mountain fault complex is not Neither fault is exposed, but the repetition of the Tusea- known with certainty because it does not truncate any rora Sandstone and the Clinton Formation indicates major fold axes. The faults of the complex, however, that they are north-dipping high-angle reverse faults. do cut off the axes of several small folds which seem to The dip on these faults is uncertain ; therefore, the slips be contemporaneous drag phenomena. are also uncertain. Structural reconstruction^ however, indicate that the stratigraphic displacement of White BIG LIOK MOUNTAIN FAULT COMPLEX Horse fault increases gradually eastward and may The Big Lick Mountain fault complex strikes east- range from about 800 to 1,800 feet. They also indicate northeast from the western part of the Lykens quad­ that the slip of the Round Head fault may b3 about 500 rangle to the western part of the Tower City quadrangle feet. on the north-dipping south limb of the Donaldson syn- cline (GQ-698, 701; Wood and Trexler, 1968c, sheets HIGH-ANGLE FAULTS IN THE NOETHEEN PART OF THE ABEA 1, 3). The faults of the complex are not exposed. Rec­ A series of north^striking, east-dipping, high-angle ords of the Williamstown mine show that the faults are reverse faults cut across the subsidiary folds of the generally north dipping, but that in some localities they south limb of the Broad Mountain anticlinorium (GQ- are overturned near the surface (Wood and Trexler, 690 ; Wood and Trexler, 1968;b, sheet 1) . Thes- faults are 1968c, sheet 4). The records also show that the displace­ not exposed, but their presence is proved by offsets of ment of the faults of the complex ranges from 0 to 2,000 stratigraphic units and fold axes. The dip slips of these feet and increases either updip or downdip. The dis­ faults range from 0 to about 400 feet and average about placements of the North and South Branches of the 200 feet. complex average about 200 and 600 feet, respectively. Although the faults in the northeastern part of the Two small folds are truncated by a branch of the Big Minersville quadrangle cut many other faults and folds, Lick Mountain fault complex in the upper part of the three are truncated by the Reservoir fault. Thus, they water gap north of Lykens (Wood and Trexler, 1968c, are younger than the folding of the area but are older sheet 3). These flexures are undoubtedly drag folds that than nonfolded thrusts, such as the Reservoir fault. formed during faulting and are thus useless in deter­ Structurally, they are important because th^y indicate mining the relations between major folding and fault­ that the northeastern part of the area was compressed ing. Although the dip of the faults of the complex is from east to west during the time that intervened be­ generally opposite that of the faults of the Rausch tween regional folding and latest thrust faulting. This Creek and Coal Mountain complexes, the close relation­ episode of east- west compression is discernable only by ship between the three complexes and the core of the these faults and by the ,possible westward slip of the Donaldson syncline can be interpreted to indicate that Sweet Arrow fault zone (p. 105). the complexes and the syncline are for the most part contemporaneous. TEAB FAULTS APPLEBEE FAULT Tear faults are common throughout the are-r , but those The Applebee fault trends east-northeast from the large enough to show at scales of 1 : 12,000 ar d 1 : 24,000 southern border of the Pine Grove quadrangle to the are present only in the central and southern parts. The east border of the area (GQ-689, 691). The fault fol­ principal tears are the Beuchler and East Branch Black- lows the crest and north slope of Blue Mountain and wood faults and the southwestern part of the Black- the south limbs of the Swope anticline and Pine Grove wood fault (GQ-691). Four other smaller tear faults syncline. It is not exposed, but the westward truncation offset the south limb of the Dauphin syncline, striking and the local structural elimination of rocks of the Clin­ nearly at right angles to the regional structural grain. ton Formation in both the foot and hanging walls indi­ In addition, a small tear fault is present between the STRUCTURE 109

Hentzes and Middle Mine Hill faults near Donaldson EAST BRANCH BLACKWOOD FAULT in the Tremont quadrangle (GQ-692; Wood and Trex- The East Branch Blackwood fault is a nortl

SHORT MOUNTAIN FAULT bedded sandstone, are less abundant and less well The Short Mountain fault is a folded bedding-plane formed in thicker bedded siltstone and sandstone, and fault on the north and south limbs of the Donaldson and are poorly formed and widely spaced in tl ick-bedded Shiro synclines in the western part of Lykens quad­ conglomerate and shale. rangle (GQ-701; Wood and Trexler, 1968c, sheet 3). Joints that trend nearly parallel to the strike of It is confined between the Lykens Valley Nos. 4 and 5 bedding, regardless of dip, are termed "strike joints"; coal beds of the Tumbling Run Member of the Potts- those that trend nearly perpendicular to th^ strike of ville Formation and at most places directly overlies the bedding and are nearly vertical are termed "dip joints." Lykens Valley No. 5 coal bed or is separated from this All other joints are termed "oblique." coal bed by only a few feet of rock. Strike joints are present in most outcrops. They gen­ The plane of the Short Mountain fault is discon- erally are planar in thin-bedded sandstone and siltstone, tinuously exposed in a series of strip pits on the south but are commonly irregular and curvilinear in thicker limb of the Shiro syncline for a distance of about 1 bedded conglomerate and shale. mile near the west border of Lykens quadrangle. It Most dip joints are persistent smooth planes that is also exposed on the north slope of Coal Mountain slice cleanly through all rock constituents, ^ich as con­ south and southwest of Gratz. cretions and pebbles. They are common in most ex­ The lower 50 to 100 feet of the upper plate of the posures and tend to be slightly irregular and curvi­ Short Mountain fault is composed of hard thick beds linear in coarser grained rocks, but are le?s irregular of sandstone and thinner beds of small-pebble conglom­ and curvilinear than are either the strike or oblique erate. The upper part of the lower plate consists in joints. ascending order, of 12 ± feet of the Lykens Valley No. Locally, oblique joints are numerous, frit they are 6 coal bed; 12 feet of shale, siltstone, and sandstone; commonly less conspicuous, extensive, and consistent and 6± feet of the Lykens Valley No. 5 coal bed. in strike than the other types of joints. Some are planar Locally, the fault plane furrows through the Lykens but most are irregular and curvilinear. They generally Valley No. 5 coal bed or ridges, so that a few feet of break around rock constituents, such as concretions and carbonaceous shale are present between the coal bed pebbles. and the fault plane. The authors measured 1,393 joints at 2£^ localities. The Short Mountain fault is well exposed in two The attitudes of the joints at these localities are shown strip pits a few hundred feet south of where the Donald- 011 the tectonic map (pi. 4). These data clearly indicate son syncline dies out in the western part of the Lykens that strike and dip joints dominate the joint system. quadrangle. In these pits the fault is folded over an However, the data are so obscured by other structural unnamed anticline. The rocks in the upper plate dip symbols on the map that a series of diagrams (fig. 41) gently southeastward on the south limb of the anticline were compiled to summarize some of the relations be­ and northward and northeastward on the north limb. tween joints, structural grain, and regional plunge. In contrast, the rocks in the lower plate, although Strike joints composed about 28 percent of the 1,393 generally conforming to the anticline, have been con­ measured, dip joints, about 25 percent, and oblique torted into a series of drag folds. In these folds, the joints, about 47 percent. Strike and dip joints dominate Lykens Valley No. 5 coal bed commonly is partly or the joint sets (fig. 41), except in the south half of the wholly truncated on the anticlinal crests and is fully Pine Grove quadrangle and in the eastern half of the preserved in the synclinal troughs. The trend of the Tremont quadrangle. In these localities, oblique joints axial lines of the drag folds indicates that the upper striking from N. 30° to 60° E. are most common. plate of the fault slipped northward, but slickensides The arithmetic mean strike of the strike joints range show that the latest movement was west or northwest. from N. 55° E. in the southern part of the Tower City The amount of slip on the Short Mountain fault is quadrangle to N. 78° E. in the Klingerstown quadrangle unknown because of the lack of truncated stratigraphic and the northern half of the Tower City quadrangle; or structural features that could be used to determine for the area as a whole, it is N. 72° E. About 65 percent relative displacement. However, it seems probable that of the strike joints form acute angles with overlying the slip does not exceed several hundred feet. bedding planes in the downdip direction, about 10 per­ cent are perpendicular to the bedding, and about 25 JOINTS percent form obtuse angles with overlying bedding Joints are abundant at many outcrops, but are sparse planes. or absent at others. They are most abundant and best The average strike of bedding and the average strike formed in thin-bedded siltstone and thin- to medium- of fold lines (structural grain) ranges frori N. 52° E. 22'30' I 76°15' EXPLANATION z-

w 50 I0'~" 10 50 Percentage Strike of joints, by percentage, in 30° intervals (203) Number of joints measured

Arithmetric mean direction of strike joints

Arithmetric mean direction of dip joints 50 O 50 SW 0° [ 0° NE

18 Percentage Dip of dip joints, by percentage, in 15° in­ tervals. Vertical interval joints divided equally between 75°-90° northeast and JOINT PLOTS BY QUADRANGLE AND PART OF QUADRANGLE southwest. 18 is percentage of vertical joints

Regional plunge

Strike of structural grain

0 3 MILES

JOINT PLOTS IN NORTHWESTERN AND JOINT PLOTS IN REPORT AREA SOUTHEASTERN PARTS OF REPORT AREA

FIGURE 41. Orientation of joints in the report area, with reference to regional plunge and strike of structural grain. 112 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNST1LV1ANIA in the southern part of the Lykens and Tower City In this area there is an absence of shear joints vhile a strike quadrangles to N. 82° E. in the Klingerstown quad­ and dip set prevail. The attitudes of these sets suggest that rangle; it is N. 72° E. for the area as a whole. The angle jointing formed shortly after the folds were defined. between the arithmetic mean strike of the strike joints In the description of strike joints it was indicated and the average structural grain ranges from. 6° in the that 65 percent form acute angles with overlying bed­ eastern half of the Tremont quadrangle to 0° in the ding planes in the downdip direction and only 25 per­ western part and in the northern parts of the Lykens cent form obtuse angles. This relationship indicates that and Tower City quadrangles. The average angle be­ these joints probably were rotated slightly parallel to tween the strike joints and the structural grain is 2° if their strikes by mass movement of material from the each quadrangle is considered individually, but it is 0° axial parts of synclines towards the axial pr,rts of anti­ for the area as a whole. clines during folding. Thus, the strike joints must have The arithmetic mean strike of the dip joints ranges been in existence before large-scale folding. from N. 5° W. in the northern part of the Tower City Similarly, in the description of the dip jcrnts, it was quadrangle to N. 34° W. in the southern parts of this shown that 45 percent are inclined to the southwest, quadrangle and the Lykens quadrangle. It is N. 18° "W. whereas only 32 percent are inclined to the northeast. for the area as a whole, which is exactly perpendicular This suggests that these joints were rotated slightly to to the arithmetic mean strike of the strike joints and the the southwest after formation. The average 6° NE. average structural grain. plunge of structural features records a regional tilting The average regional plunge of structural features is that is concordant with the degree of rotation of the 6° in a N. 72° E. direction. Most dip joints are inclined joints. The dip joints, therefore, also seem to have been slightly to the southwest, which is expectable, with a in existence before the folding. northeast regional plunge. Twenty-three percent of the The data from the area thus indicate that the strike dip joints are vertical, 29 percent hade 1° to 15° SW., and dip joints were in existence before large-scale fold­ and 16 percent hade more than 15° SW. In contrast, ing and are unrelated to the earlier low-angle folded only 17 percent of these joints hade from 1° to 15° NE., thrust faults. This conclusion largely supports that and 15 percent hade more than 15° NE. reached by Parker (1942) and disagrees with that of The exact parallelism of the structural grain and Sheppard (1956). However, it modifies Parker's con­ strike joints and ths exact perpendicularity of the dip clusion as follows: the first effect of the Appalachian joints to the strike joints and grain indicate that both orogeny was not jointing; it was low-angle thrust types of joints were formed by the orogenic forces that faulting followed by jointing. established the structural grain. CLEAVAGE The orientations of the joints of the area do not seem to have been noticeably affected by their proximity to Fracture and flow cleavage are common in incompe­ the low-angle folded thrust faults, but they have been tent rocks, but are largely absent in more competent greatly affected by the folding. rocks. Both are relatively common in shale and siltstone The age of the joints in the Appalachian Mountains of the Mandata Member of the Helderberg Formation, and has not been positively deter­ the Needmore Shale, the Marcellus Shale, tb^ lower and mined. Parker (1942, p. 392-393, 407) recognized joints upper members of the Mahantango Formation, and in sets that are similar in all respects to those of the area the more incompetent rocks of the CatsHll, Mauch in eastern, central, and southern New York and north­ Chunk, and Llewellyn Formations. ern Pennsylvania. He concluded that jointing clearly Flow cleavage is best developed near the axes of folds preceded folding and was the first structural effect of in the southern part of the area, generally is much less the Appalachian orogeny. This conclusion was based well developed in the northern part, but locrlly, is well- upon strike joints fanning the crests of anticlines, perid- developed near the axes of the more intensively de­ otite dikes intruding the dip joints, and minor faults formed folds. In some outcrops it has obliterated all offsetting both the dip and strike joints. traces of bedding, other sedimentary features, and fos­ Sheppard (1956) reached a somewhat differing view sils. Throughout the area, flow cleavage generally is as to the age of jointing in his study of the region be­ vertical or steeply inclined to the southeast, r,nd at many tween the Susquehanna River and Swatara Creek. The places the intersections of the cleavage and the bedding latter lies in the southern part of the area. He form an excellent lineation that parallels the axes of concluded: adjacent folds. At other places the intersections are so closely spaced that linear rock fragments tave formed After rotation of the bedding back to horizontal, no correla­ tion of the joint sets was obtained, indicating that jointing had whose bounding surfaces are the bedding and cleavage not existed prior to folding. planes. These fragments are as much as 1 foot long and STRUCTURE 113 1 inch thick and are commonly referred to as "pencil not been metamorphosed, except locally near the shale." Piedmont. Most fracture cleavage is in shale and siltstone beds The Anthracite region includes much of the northern less than 2 feet thick, which lie between thicker more and central parts of the Folded Appalachians in easx^rn competent beds. Where the bedding is upright, it in­ Pennsylvania. Its northern boundary lies several miles variably dips more steeply than the bedding and paral­ north of the structural front of the mountains on the lels the axial planes of nearby folds; but where the Allegheny Plateau. The southern boundary is Blue rocks are overturned, it dips less steeply than the bed­ Mountain, the east border is approximately defined by ding. In the places where siltstone and shale beds are the west margin of the Pocono Plateau, and the vest thicker than 2 feet, fracture cleavage generally is absent, border is roughly defined by the Susquehanna Kiver. and a sheeting fracture of unknown origin commonly The report area lies in the southwestern part of the parallels the bedding. region and is characterized by a more complex structure Much of the anthracite in the area breaks into frag­ than are most other parts. ments of various sizes along conchoidal fractures, al­ The southeastward increase in structural complexity though, locally, it is fracture cleaved. In the places of the mountains is especially apparent in the Antl ra- where deformation was not too severe, the cleavage cite region because of the control provided by mining. planes are widely spaced, but where deformation was Arndt and Wood (1960), after detailed mapping in the more profound, the planes generally are closely spaced. southwestern part of the region and reconnaissance else­ Locally, where deformation was intensive, the coal lying where, divided the region into four structural provinces. between cleavage planes has been fractured into numer­ This division is based upon the increasing structural ous thin conchoidal shelly fragments that have been ro­ complexity and was adopted after recognizing that tated parallel to the bedding of adjacent more competent structural features progressively formed in both t^m- rocks, and in a few places the coal has been pulverized. poral and geographic sequences. In the western and central parts of the Lykens quad­ Temporally, the structural features of the Anthracite rangle (Wood and Trexler, 1968c, sheet 3), the Lykens region formed progressively in the following sequence Nos. 4, 5, and 6 coal beds on the south limb of the Don- of increasingly more complex stages as quoted from aldson syncline have the characteristic blocky or cubical Arndt and Wood (1960, p. B182); cleat of semianthracite. On the north limb they gen­ 1. Folding of horizontal strata into broad anticlines and erally are intensively fracture cleaved and in a few synclines. places are pulverized, which suggest that there was more 2. Low-angle thrusting and imbricate faulting, followed by for­ pressure and differential movement of beds on the north mation of subsidiary folds on the larger folds to develop limb than on the south. anticlinoria and synclinoria. Additional low-angle thrurfing followed by high-angle thrusting accompanied the subsid­ The presence or absence of fracture cleavage and iary folding. cleat determines whether, during mining, anthracite 3. Folding of low-angle and high-angle thrusts, and offsetting of breaks into blocks, large conchoidal fragments, smaller pre-existing structural features by high-angle thrusts. shelly fragments, or a powder. This, in turn, has greatly 4. Development of overturned folds, and offsetting of overtu-ned folds by tear faults and high-angle thrusts. influenced the market value of anthracite, the proce­ dures locally used in mining, and the relative safety of In the sequential development of the structure of the mining. Anthracite region, Arndt and Wood demonstrated that REGIONAL TECTONICS structural features characteristic of each temporal stage were also characteristic of geographic areas or structural The report area is a small part of the Appalachian provinces. They concluded that any area that contains Mountain system. In Pennsylvania this mountain sys­ structural features typical of a specific stage underwent tem is divided into two structural provinces: the Folded (deformation characteristic of each preceding stoge. Appalachians and the Piedmont. In general, the com­ The provinces are as follows: plexity of tectonism increases southeastward from the northwestern structural front of the mountains across 1. Northeastern part of the Anthracite region. This province is the Folded Appalachians and the Piedmont to the At­ characterized by structural features typical of stage 1. lantic Coastal Plain. Igneous and metamorphic rocks 2. North-central part of the Anthracite region. This province contains structural features of stage 2 superimposed on of and early Paleozoic age have been in­ those of stage 1. tricately deformed and altered in the Piedmont. Sedi­ 3. South-central part of the Anthracite region. This province mentary rocks of Paleozoic age in the Folded Appalach­ contains structural features of stage 3 superimposed on ians have been intensively folded and faulted, but have those of stages 1 and 2. 114 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSY1LV1ANIA

4. Southernmost part of Anthracite region. This province con­ This discordancy is believed to have been caused by tains structural features of stage 4 superimposed upon those differential transmission of compressive forces through of stages 1-3. strata of differing competency. The following evidence The progressive temporal and geographic deforma­ illustrates this belief. During the early stages of the tion described by Arndt and Wood is here modified so formation of the Minersville synclinorium, the deform­ that the last episode of deformation of stage 4 is low- ing forces were transmitted northwestward by compe­ angle faulting rather than high-angle faulting. Wood tent rocks above the middle member of the Mauch and Kehn (1961, p. 263) incorrectly concluded that the Chunk, by incompetent rocks of the member, and by Sweet Arrow fault zone was high angle. This conclu­ competent rocks below the member. Because the com­ sion guided Arndt and Wood in determining their petency of these rock units differed, they transmitted sequence of development. Later work by Wood, Kehn, the forces northwestward differentially, and the compe­ and Trexler convinced them that the fault zone was tent rocks above the middle member tore loo^e from the high angle near the surface but probably low angle at incompetent rocks of the member along a fracture sys­ depth. tem that formed into the Pottchunk fault and its asso­ The report area includes parts of structural provinces ciated imbricates. Similarly, the competent rocks below 3 and 4 of Arndt and Wood. The boundary between the middle member tore loose along the MairJiono fault these provinces, from east to west, across the area is and other similar fractures. In addition, the Hegins successively the Newtown fault, the crest of Big Lick fault formed in the medial and lower parts of the mem­ Mountain anticline, the structural maze beneath the ber as the result of differential adjustments. borough of Tremont, the trough of the Llewellyn syn- As the deforming forces of the Appalachian orogeny cline, Eausch Creek, Blackwood fault, and the trough increased in intensity, the Minersville synclinorium of the Dauphin syncline (pi. 4; GQ-690, 691, 692, 698, deepened, movement decreased or ceased on the Pott- 701). Except for the areas at Tremont and Rausch chunk and Mauchono faults, and the limbs of the syn­ Creek, the boundary is everyhere located at faults or at clinorium developed many subsidiary folds The crests the crests and troughs of folds. In these localities, how­ of the subsidiary anticlines below the Mauchono fault ever, it is defined on the basis of geographic location and the troughs of the subsidiary syncline? above the rather than structural features. At most places the Pottschunk fault were controlled in their upward and boundary separates upright strata to the north from downward formation by the preexisting structural dis- alternating belts of overturned and upright strata to cordencies at these faults. They also were controlled the south. by the buffering action of the incompetent strata of The controlling structural feature of the area was the the middle member. During the formation of the sub­ Minersville synclinorium. The trough of the synclinori- sidiary folds, high-angle faulting took place, princi­ um, or nearby smaller structural features, separates pally above the Pottchunk fault; at about th^ same time generally upright strata from generally overturned or shortly thereafter, the south limb of the synclinorium strata. During the latter part of the orogeny it probably was overturned. This was followed by the formation of separated a foothills folded and faulted belt from a the Blackwood, Beuchler, and Sweet Ar^-ow faults massif of largely overturned and intensively deformed which crosscut the limb without regard to the preexist­ strata. The boundary between structural provinces 3 ing structural grain. and 4 lies at or near the trough and is one of the more Broad Mountain and New Bloomfield anticlinoria important tectonic boundaries of the ancestral Appala­ controlled the formation of many smaller structural chian Mountains, perhaps comparing locally in impor­ features in the northern and western parts of the area. tance with the boundary between the Folded Appala­ These large fold systems, however, do not seem to have chians and the Piedmont. played as important roles in the tectonic formation of Structure sections (GQ-689, 690, 691,692) show, with the area as did the Minersville synclinorium. Nor do reference to the top of the middle member of the Mauch they appear to separate large tectonically different areas Chunk Formation, that the altitudes of the bottoms of or provinces as does the synclinorium. the larger synclines descend evenly southward towards Reasons for the Minersville synclinorium being tec­ the trough of the Minersville synclinorium. Similarly, tonically so important are not understood. However, as the sections show, with reference to the base of the mid­ illustrated on structure sections (GQ-689, 690, 691, 692, dle member, that the altitudes of the tops of the larger 698, 701), the Mauch Chunk Formation is believed to anticlines descend evenly southward towards the thicken markedly in the trough. This thickening may trough. Although the rate of descent of the synclinal have been responsible for the localization of the various troughs and anticlinal crests are individually concord­ types of structural features to the north and south. It ant, they are decidedly discordant each to the other. is also possible that the trough was superimposed upon STRUCTURE 115 a structural depression or zone of weakness that formed seem to have flowed or to have been forced into the during the Taconic orogeny. space previously occupied by the upward-moving anti­ A major tectonic fact determinable from the struc­ clinal crests. The cores of the anticlines, therefore, were ture sections and geologic maps (GQ-689, 690, 691,692) always supported, and voids did not exist at any time. is that rocks older than the middle member of the Mauch The process of transferring strata from the limbs of Chunk Formation are discordant at many places with anticlines to the cores logically occurred most commonly those younger than the middle member. This discord­ in areas where the amplitude of folding increase-} up­ ancy suggests that the middle member functioned dur­ ward, as in the report area. The amount of incraase in ing deformation as a tectonic buffer which separated amplitude of an anticline is dependent upon the severity discordantly transmitted sets of forces. This separation of differential compression, the amount of stratigrapic resulted in the formation of the Pottchunk and Mauch- thickening in the core, and, lastly, upon the numHr of ono faults. detachment planes existing within the confines of the DEPTH OF DEFORMATION anticline. There is little positive geophysical evidence to show During the last 50 years a difference of opinion has whether the Precambrian basement complex is involved become increasingly apparent among geologists study­ in the deformation of the Folded Appalachian but ing the Appalachians as to whether the Precambrian what is known is discussed below. basement complex is involved in the structural features present in the Paleozoic rocks. The available data are Joesting, Keller, and King (1949, p. 1761) deter­ more easily interpreted to support the concept that the mined by an aeromagnetic survey of part of central basement complex is not greatly involved. Pennsylvania that the basement complex lies at a greater The geometry of the folds that are depicted on struc­ depth southeast of the Appalachian structural front ture sections (GQ-689, 690, 691, 692, 698, 699, 700, 701) than it does to the northwest. This relationship is anom­ indicates that all folds decrease in amplitude with in­ alous because Lower Cambrian rocks, which normally creasing depth. Projection of the rate of decrease to lie only a short distance above the complex, crop out depths greater than 12,000 feet illustrated on the sec­ southeast, of the front, and Pennsylvania!! rocks, which tions shows that all but the largest folds apparently lie thousands of feet above the Lower Cambrian rocks, die out between 20,000 and 25,000 feet below the crop out northwest of the front. Joesting, Keller, and surface and that even these disappear at about 40,000 King concluded that the "basement surface is net de­ feet. According to Colton (1961, pi. 11), 35,000 to 40,000 formed concordantly with the highly folded Paleozoic feet of Paleozoic rocks underlie east-central Pennsyl­ rocks." vania. If the concept of decreasing amplitude is correct, Five north-south aeromagnetic lines of the U.S. Geo­ the Precambrian rocks probably were not involved in logical Survey extend across the area from the New the folding, were not as greatly compressed laterally York-Pennsylvania border to Marietta, Pa. Magnetic southeast to northwest as were the sedimentary rocks, anomalies due to the basement complex are prominent and therefore, must be separated from the sediments by near the border. Depth determinations computed from planes of detachment. Gray and others (1960, structure these anomalies indicate that the complex lies about section D-D'} , Grwinn (1964, p. 897), Woodward (1964, 13,000 to 14,000 feet below the ground surface (W. J. p. 351), Rodgers (1963,p. 1534-1535), and Perry (1964, Dempsey, oral commun., 1960), which is in close agree­ p. 668) have postulated the existence of such planes in ment with a depth of 14,500 feet determined from strati- the lower part of the Paleozoic sequence in western and graphic data (Colton, 1961, fig. 4). About 30 miles central Pennsylvania. south of the border these magnetic anomalies disapr>ear, STevin (1936, p. 65) andVerWiebe (1936, p. 933-936) and a gentle smooth southward-inclined magnetic g~adi- argued that anticlines cannot form unless supported ent prevails for about 90 miles to near Campbelltown. from below by the basement. According to their reason­ According to Dempsey, the smooth gradient may be due ing, folds could not form above detachment faults un­ to any of several factors: (a) a basement complex that less similar folds lay directly below, because voids would is not highly magnetic and does not contain units of occur at the cores of the anticlines. Their reasoning is greatly differing magnetic intensities; (b) a complex incorrect, because at many places rocks above and below buried too deeply to influence the airborne magne^om- thrust faults and detachment planes are known to be eter (more than 25,000 ft); or (c) an upper surface of differentially folded. In many detached fault blocks, the the complex that slopes gently and smoothly southward troughs of the synclines seem to be largely limited in and does not rise into the cores of anticlines or descend their downward development by detachment planes, and beneath synclines. These three possibilities are evalu­ the strata above the planes on the limbs of anticlines ated below. 116 GEOLOGY, SOUTHEKN ANTHRACITE FIELD, PENNBYILV1ANIA. Joesting, Keller, and King (1949, p. 1761 and fig. 7) ties that seem to coalesce or merge south.wr.rd towards found that in Pennsylvania the magnetic trend of the the promontory. folded Appalachians is N. 60° E., which is in strong The region east, southeast, and south of the area was contrast to the N. 30° E. strike of Appalachian fold again uplifted during the Acadian orogeny, which be­ axes in the south-central part of the State and the N. gan in latest Middle Devonian time and continued in­ 60°-80° E. strike in the central and eastern parts. They termittently into Early Mississippian time. The pre- concluded that this divergence in trends indicates a cor­ Pocono unconformity indicates that large-scale folding responding divergence between the structural trends of and perhaps faulting during this orogeny extended in­ the complex and the overlying Paleozoic rocks. This to the area in Early Mississippian time and also indi­ divergence probably indicates that the basement com­ cates that an ancestral Broad Mountain articlinorium plex is significantly magnetic. began to form. The five aeromagnetic lines cross several large anti­ The mountainous region east, south, and southeast of clines where the basement complex, if in normal strati- the area seems to have been low and tectonically quies­ graphic succession, should lie considerably less than cent during Middle Mississippian time. Near the end 25,000 feet below the surface. Near Danville, on the of the Mississippian, however, it was strongly uplifted Montour anticline, the complex should be about 13,000 and remained tectonically active with but minor periods feet below the surface (Colton, 1961, figs. 6, 7, 9). Near of quiescence throughout the rest of Paleozoic time and Elysburg, on the Selinsgrove anticline, the complex perhaps early time. Mountain building caused should be about 18,000 feet below the surface, and in by the Appalachian orogeny advanced northwestward the report area, near Line Mountain on the Frackville into the area after the youngest preserved strata of the anticline, the complex should be well above the 25,000- Llewellyn Formation of Late, but not latest Pennsyl- foot limitation of the airborne magnetometer. However, vanian age were deposited. Elsewhere in the central the smooth gradient of the magnetics across these anti­ Appalachians, mountain building during this orogeny clines argues that the complex is not deformed upwards seems to have begun during latest Pennsylvanian or into the axial parts and strongly suggests that it is earliest time (Berryhill and deWitt, 1955; everywhere more than 25,000 feet below the surface. Berry hill and Swanson, 1962) and to have ended by the It logically follows that if the complex is not up- end of Middle Triassic time. warped in the cores of the anticlines, it is not down- Although the exact timing of the Appalachian orog­ warped below the synclines, and that the upper surface eny is uncertain, the order of deformation of individ­ of the basement complex probably is relatively smooth. ual structural features or associated series of structural The numerous folds in the Paleozoic rocks and the features can be determined. probable smooth upper surface of the basement com­ The youngest sediments of Late Pennsylvanian age plex are incompatible, unless one or more detachment now present in the area were rather flat l^ing at the planes exist. It seems highly likely, therefore, that such end of their deposition. Perhaps only an additional a detachment separates the main body of Paleozoic few hundred feet of sediments accumulated, but it seems rocks from the basement. This is consistent with the ex­ more likely that many more thousands accumulated and istence of other detachment planes, such as the Mauch- have since been eroded off. Gentle folding occurred after ono and Pottchunk faults. these sediments were laid down either in latest Pennsyl­ vanian or earliest Permian time. It seems lilrely that the STRUCTURAL HISTORY earliest of these gentle folds were a rejuvenated ances­ The first structural events recorded by the rocks of tral Broad Mountain anticlinorium, the ancestral Min- the area are of Late Ordovician age. During the Middle ersville synclinorium, and the ancestral New Bloomfield and Late Ordovician time the southern part and per­ anticlinorium. haps all of the area was deformed by forces of the The intensity of deformation gradually increased, Taconic orogeny which formed mountains to the south, and the ancestral Minersville synclmorum slowly southeast, and east. The structural features that formed formed into a large shallow open fold on whose north­ in the area during the orogeny are largely unknown ern limb a series of bedding-plane faults formed at a because they are buried by younger sediments. consistent horizon near the top of the Msuch Chunk In Silurian and Early and Middle Devonian time in­ Formation. As the deformation continued increasing in termittent epeirogenic uplift extended into the area from intensity, these bedding-plane faults finally merged into the Auburn promontory. Recurrent erosion beveled the a major thrust, the Pottchunk fault. During the later underlying strata and produced a series of unconformi­ stages of the formation of this thrust fault, compres- ECONOMIC GEOLOGY 117 sion was so great that the thrust plane was gradually ECONOMIC GEOLOGY warped into minor folds at many places, and the upper COAL plate of the thrust fault was broken into a series of imbricate thrust slices that rose upward from the minor Anthracite and semianthracite have been the principal folds in the following order: Hans Yost, Dyer Run, and economic resources of the area for about 150 years, and Jugular faults and the various branches of the Mine Hill much coal has been mined during this period. fault complex. HISTORY AND METHODS OF MINING The Mauchono fault formed penecontemporaneously with the Pottchunk on the flanks and crest of the grow­ Early records report that anthracite was used by gun­ ing Broad Mountain anticlinorium. Competent strata, smiths before 1755, by blacksmiths about 1769, and by which underlay the plane of the Mauchono, moved nail manufacturerers in 1788 (Hudson Coal Co., 1932, northward relative to less competent strata, which over­ p. 24r-26). Despite this early utilization, it was 1808 lay the fault, and regionally pierced deeply into the before anthracite was successfully burnt in an open less competent strata on the crest and on the upper grate and 1812 before it was fired in a furnace (Hudson limbs of the anticlinorium. Simultaneously with the for­ Coal Co., 1932, p. 26-27,31). mation of the Mauchono, a large thrust, the Hegins A map prepared by a Mr. Schul in 1770 indicated fault, formed in the medial part of the Mauch Chunk the presence of coal near Mahanoy City and Shamokin, Formation. a short distance north of the area. However, it was 1790 After the formation of the Pottchunk, Hegins, and before Necho Alien found anthracite in the northeastern Mauchono faults, most of the anticlines and synclines part of the area on Broad Mountain (Hudson Coal Co., of the area formed into virtually their present forms as 1932, p. 29) and 1795 before a blacksmith named Whet­ subsidiary folds of the Minersville synclinorium and stone used anthracite from the Southern Anthracite New Bloomfield and Broad Mountain anticlinoria. In field in a forge. Other blacksmiths began using coal addition, numerous high-angle reverse faults fractured from the field in their forges about 1812. The first rhip- the subsidiary folds, and the south limb of the syn­ ment of coal to Philadelphia was made in 1800, but clinorium was overturned. profitable shipments were not possible until 1812. At about the time the Minersville synclinorium was Completion of Schuylkill Navigation Canal, parallel overturned, the trough and south limb were fractured to Schuylkill Kiver, in 1825 provided the first economi­ by the Blackwood, East Branch Blackwood, and Beuch- cal transportation to the Philadelphia market area. The ler faults and by smaller tear faults. Shortly thereafter, canal was 108 miles long, cost $2,200,000 to build, and the Sweet Arrow faults split off from the Blackwood incorporated the first tunnel built for transportation in fault near the crest of an overturned subsurface anti­ North America. The canal was operated at a profi4: for cline and moved upright beds in the upper plate north more than 50 years, but by the end of the 19th century and west across overturned beds in the lower plate. it had fallen into disrepair and now is obliterated at The Blackwood, East Branch Blackwood, Beuchler, most places. and Sweet Arrow faults are the youngest large faults. The anthracite industry became economically im­ A series of small northward-trending high-angle re­ portant between 1825 and 1835. By 1837, the value of verse faults and the eastward-trending Keservoir fault coal property in the Anthracite region had increased in the northern part of the Minersville quadrangle, how­ from practically nothing to several hundred dollars per ever, may be of approximately the same age. Although acre, and mining and land speculation were rampant. the slip of each of these high-angle reverse faults is neg­ As anthracite became increasingly more important, a ligible by comparison with those of the younger large railroad network gradually developed, and a lagqing faults, these and the Sweet Arrow faults show that the steel industry mushroomed, because it was for the first area was subjected to westward-directed compression time independent of bituminous coal heretofore im­ during the later stages of its structural formation. ported from Great Britain. The Appalachian orogeny apparently ended in the Kailroad construction began in the Anthracite re^rion area with the westward compression. Subsequently, the in 1828 and soon spread throughout eastern Pennsyl­ area seems to have been subjected to a long period of vania, New York, Delaware, New Jersey, and Maryland. erosion that has lasted to the present. By 1842 the final rail link with Philadelphia was com- 118 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA pleted, and the anthracite industry promptly took its gradually into the open space resulting from the re­ place as one of the economic giants of the United States. moval of the coal. From 1842 to 1880 the Anthracite region produced about Strip mining utilizes draglines, power shovels, bull­ 450 million tons of coal. The Southern Anthracite field dozers, and large dump trucks. The draglines are com­ produced about 67 million tons, or about 15 percent of monly employed to remove overburden, b^t in some this coal, and the report area produced about 27 million places they have been used to excavate coal, particularly tons, or about 5.5 percent. in the more steeply dipping beds. The capacities of pres­ Most of the large mining companies of the Anthracite ently operating draglines range from 1 to 85 cubic yards region came into existence between 1825 and 1875. The and average about 10 cubic yards. Power shovels with majority continued to operate until the 1930's, and sev­ a capacity of 1 to 10 cubic yards are the principal coal- eral continued operations until nearly the present. All excavating machines in the larger strip pits. the original companies have now discontinued mining, Many strip pits consist of long narrow excavations most have liquidated their coal and mineral land hold­ dug along the strike of steeply dipping coal b^ds. Where ings, and many have diversified into other types of a coal bed is exceptionally thick 01 where the dip is business or industry. less steep, such as on the crests of anticlines, in the Several techniques of underground mining have been troughs of synclines, or on gently inclined limbs of folds, used in the region. The basic mining techniques are the large strip pits are common. In both the long narrow room-and-pillar, chute, and longwall methods. The first strip pit and the large strip pit, the ratio cf thickness two of these have been used extensively in the area, and of overburden or waste coal seldom exceeds 25 to 1. The the longwall method has been used in the few places walls of many strip pits are several hundred feet high. where beds are flat or gently inclined. Most large mines employed the room-and-pillar EXTENT OF MINE WORKINGS method where the coal beds dip less than 20° and t he- Hundreds of small to large underground anthracite chute method where they dip more than 20°. In either mines have operated during the last 150 yer,rs. A large method, rooms and intervening pillars were excavated, number of surface openings into these mines are shown and considerable timbering was necessary to support the on the coal maps (Wood and Trexler, 1968 b, c). How­ roof. After the completion of a series of rooms above ever, hundreds of additional mine openings are not a haulageway, the pillars were gradually removed, and shown on the coal maps because they have been de­ the roof rock was supported by additional timbering. stroyed by strip-mining operations, have collapsed, or If the roof rock could be adequately supported by tim­ have been completely overgrown and concealed by bering or could be induced to collapse gradually at a vegetation. distance from individual pillars, all coal was removed. The linear extent of underground haulageways, tun­ In most places, however, the roof was unstable and soon nels, and drifts is unknown, but probably amounts to at began to sag or crack, and mining was discontinued least 1,000 linear miles and may be as great as 2,000 to after removing only a part of each pillar. The stage 3,000 miles. There is also a vast series of underground of mining in which rooms and pillars were excavated rooms in the numerous coal beds that are interconnected by either method was commonly known as "first min­ at many places and are isolated at others. ing" and usually resulted in the extraction of about 50 The original topographic configuration of some of the percent of the coal in a bed. The stage of mining in more intensively mined parts of the area has been com either method during which pillars were partly or pletely changed by the combined results of strip mining, wholly removed was known as "second mining" or "rob­ underground mining, and waste dumping. TTie topogra­ bing." This latter stage usually resulted in the extrac­ phy has been altered so swiftly in some localities that tion of 10 to 20 percent additional coal for a maximum relatively modern topographic base maps are useless for average extraction of 60 to 70 percent. These extraction geologic mapping or determining locations. Aerial pho­ percentages are based on numerous mine maps from the tographs commonly are usable for geologic mapping for area that show the dimensions of rooms and pillars only 3 to 5 years, and in areas of very active mining, during both phases of mining. photographs have become obsolete in 1 to 2 years. Longwall mining has been attempted only where the coal beds are gently inclined or flat. In this method a CONDITION OP MINE WORKINGS working place was extended for several hundred feet The drifts, shafts, slopes, tunnels, and other under­ at right angles to a haulageway. Successive slices of ground mine workings are deteriorating rapidly. Large- coal were then removed from the entire length of the scale mining ceased at most places during the early working place, and the roof was allowed to collapse 1930's and has ceased elsewhere in the last several years. ECONOMIC GEOLOGY 119 The workings of these abandoned large mines are gen­ extracted (F. T. Moyer, oral commun., 1963) or upon erally unsafe because of caving, rotting timbers, threat­ arbitrary quadrangle borders such as those that tound ening collapse, mine gas, and water. In the abandoned the area and that have little relation to individual coal smaller mines, conditions are the same or worse. Despite fields, commercial districts, counties, and mining or in­ this generally poor condition of abandoned mine work­ spection districts. ings, several score of closely inspected small mines oper­ Unfortunately, the production figures of the Federal ate intermittently. Government and the State government differ. In some Most abandoned and many operating underground years this difference is as much as 8 million net tons; mines contain pools of water. These mine-water pools for most years it is negligible statistically, amounting either completely fill the workings or are isolated in to several hundred thousand tons or less. The difference parts of the workings. Many mine-water pools overlie is due to the inclusion of dredged coal in the Federal other parts of the same mine or adjacent mines. The figures and the fact that the Federal tonnages are b<\sed location and size of most mine-water pools are known, upon cleaned coal reported by breaker plants, whereas but many others are unknown. Modern underground the State tonnages are based upon cleaned coal reported mines occasionally penetrate these unknown pools, and by mines. The difference in total tonnage from 1882 to the miners may be either severely injured or drowned. 1960, excluding dredged coal from the Federal ton­ The mine-water pools commonly are supplied from nages, amounts to only 4,516,540 net tons, even though two sources: direct connections with the surface for some years differences are 3 to 8 million net tons. through the original mine openings and through strip Table 2 gives the total and yearly production of pits, and percolating ground water which enters the the Anthracite region from 1769 to 1960, Tonnages pools from unmined coal beds and adjacent strata. for the years 1807 to 1960 were tabulated from the U.S. Bureau of Mines (Moyer and others, 1961, p. 154-155; PBODUCTION Try on and Mann, 1928, table 9) and for the years 1769 The production from the Anthracite region is known to 1806, they were tabulated from "Pennsylvania's Min­ with considerable exactitude from 1882, when the Fed­ eral Heritage" (Pennsylvania Bur. Statistics and Infor­ eral Government and the Commonwealth of Pennsyl­ mation, 1944). Table 2 also gives the yearly production vania began keeping comprehensive records, to the pres­ of the Southern Anthracite field as reported by the U.S. ent, but it is less well known for the period preceding Bureau of Mines from 1924 to 1960 (U.S. Bur. Mines, 1882. Before 1882 the records were largely based on 1928-32, 1933-60), U.S. Geological Survey from 1913 census reports supplemented by State and trade sources. to 1923 (U.S. Geol. Survey, 1883-1927), and the Penn­ Production apparently began about 1755, but it was sylvania Second Geological Survey (1882-89, various 1824 before it exceed 10,000 net tons per year. reports on anthracite). The production of the Southern Pennsylvania anthracite was the chief mineral fuel Anthracite field for all other years was estimated by of the United States from about 1824, when 13,685 net the authors after determining the year-to-year produc­ tons was produced, to 1870, when the nation's produc­ tion percentage of the Southern Anthracite field with tion of bituminous coal exceeded that of anthracite from reference to the total yearly production of the Anthra­ Pennsylvania (Tryon and Mann, 1928, p. 528-533). An­ cite region. thracite production has exceeded 1 million tons a year The production of the area was determined from since 1839. records for the following years: 1882-89, 1910, 1915, The amount of anthracite extracted from the area is 1920, 1925,1930, 1935,1940, 1945,1950,1955, and 1960. difficult to determine because records of the Federal The tonnages for all other years were estimated by Government are maintained for the entire region, indiv­ determining the average 5-year production percentage idual coal fields, commercial districts, counties, and not of the area with reference to the year-to-year produc­ by mine or breaker plant. They are, however, based tion of the Southern Anthracite field. largely upon the amount of coal cleaned at breaker The production of the Anthracite region from 1769 plants (F. T. Moyer, oral commun., 1963). to 1960 was 5,227,392,894 net tons. The Southern An­ Records of the Pennsylvania Department of Mines thracite field in the same period is estimated to have and Mineral Industries are maintained for the entire produced about 755 million net tons and the report area region, mining or inspection districts whose numbers about 318 million net tons. The value of coal produced and boundaries have changed many times, commercial in the Anthracite region from 1890 to 1960 was rJbout districts, and the larger mines. The records are based $17.1 billion (Moyer and others, 1961, p. 154-155) and upon the amount of cleaned coal reported by mines after is estimated to have been about $1 billion from 1769 processing of raw coal at breaker plants. Thus, neither to 1890, for a total of about $18.1 billion from 1769 to Federal nor State records are based upon the raw coal 1960. During the same period the Southern Anthracite 120 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYILV1ANIA

TABLE 2 Production of anthracite, in net tons, from the Anthracite TABLE 2 Production of anthracite, in net tons, from the Anthracite region, Southern Anthracite field, and report area region, Southern Anthracite field, and report area Continued

[Southern Anthracite field: Estimated tonnage from 1769-1880 based on average Year Anthracite region 1 Southern Anthracite Report area 3 percentage of production for years 1880-1960 equals about 70 million. Report area: field 2 Estimated percentage from 1769-1880 based on average percentage of production for years 1880-1960 equals about 28 million.] 1900 6, 900, 000 3 3, 000, 000 Year Anthracite region * Southern Anthracite Report area 2 1899_ __ 60, 418, 005 3 6, 600, 000 3 2, 900, 000 field 3 1898- _ 53, 382, 645 3 5, 900, 000 3 2, 600, 000 1897- _ 52, 611, 681 3 5, 800, 000 3 2, 600, 000 1960 __ __ 18,817,441 4, 530, 628 2, 856, 521 1896- _ 54,346,081 3 6, 000, 000 3 2, 700, 000 1959 __ __ 20,649,286 5, 269, 930 3 3, 200, 000 1985 __ 57, 999, 337 3 5, 800, 000 3 2, 000, 000 1958 ____ 21, 171, 142 5, 086, 583 3 3, 000, 000 1894 __ 51, 921, 121 3 4, 600, 000 3 2, 100, 000 1957 ____ 25,338,321 6, 061, 879 3 3, 400, 000 1893 __ 53,967,543 3 4, 800, 000 3 2, 200, 000 1956 ___ _ 28,900,220 7, 425, 427 3 4, 100, 000 1892_ __ 52,472,504 3 4, 700, 000 3 2, 100, 000 1955 ____ 26,204,554 5, 958, 776 3, 313, 008 50,665,431 3 4, 600, 000 3 2, 100, 000 1954 ____ 29,083,477 5, 952, 615 3 3, 100, 000 1953 ____ 30,949,152 7, 352, 940 3 3, 400, 000 1890___ 46,468,641 3 4, 200, 000 3 1, 900, 000 1952 __ __ 40, 582, 558 8, 979, 129 3 3, 300, 000 1889- __ 45,546,970 3, 703, 952 1, 703, 519 1951 ____ 42,669,997 8, 801, 942 3 3, 200, 000 1888 __ 46,619,564 3, 646, 251 1, 721, 195 1887 -_ 42,088,197 3, 971, 418 1, 903, 674 1950 ____ 44,076,703 9, 100, 374 3, 264, 940 1886- 39,035,446 3, 838, 727 1, 646, 157 1949 ____ 42,701,724 8, 261, 266 3 2, 800, 000 1885-__ 38,335,974 3, 970, 638 1, 807, 107 1948 ____ 57,139,948 12, 118, 732 3 4, 100, 000 1884 __ 37, 156, 847 3, 537, 407 1, 639, 234 1947 ____ 57,190,009 11, 881, 102 3 4, 050, 000 1883 __ 38,456,845 3, 541, 124 2, 085, 893 1946_ ___ 60,506,873 13, 203, 552 3 4, 500, 000 1882. __ 35,121,256 3, 198, 974 1, 897, 761 1945 __ _ 54,933, 909 12, 290, 357 4, 503, 257 1881. _ 31,920,018 3 3, 150, 000 3 1, 700, 000 1944_ ___ 63,701,363 14, 285, 542 3 5, 150, 000 1943___ __ 60,643,620 12, 006, 749 3 4, 350, 000 1880- _ 28,649,812 3 2, 600, 000 3 1, 500, 000 1942 ____ 60,327,729 10, 123, 626 3 3, 700, 000 1879_ __ 30,207,793 __ _ 1941 ____ 56,368,267 8, 561, 966 3 3, 100, 000 1878- __ 21, 689, 682 _ _ 1877. __ 25,660,316 _____ 1940 ____ _ 51,484, 640 7, 437, 509 2, 841, 099 1876_ __ 22,793,245 _____ 1939 ____ 51,487,377 7, 051, 710 3 2, 650, 000 1875 __ 22,485,766 _ _ _ 1938___ __ 46, 099, 027 6, 073, 139 3 2, 300, 000 1874___ _ _ 24,818,790 1937 ____ 51,856,433 6, 067, 922 3 2, 300, 000 1873- __ 26, 152,837 __ _ 1936 ____ 54,579,535 6, 877, 678 3 2, 600, 000 1872 ___ 24,233, 166 __ _ 1935 ____ 52,158,783 6, 190, 511 2, 588, 155 1871_ _ 19,342,057 _ _. 1934 ____ 57,168,291 7, 467, 559 3 3, 300, 000 IQOO 4Q K.A-I 244 6, 352, 024 3 2, 800, 000 1870 __ 15,664,275 _ __. 1932 __ ___ 49,855,221 7, 030, 323 3 3, 100, 000 1869 __ 17, 083, 134 __ . 1931___ __ 59, 645, 652 7, 958, 000 3 3, 500, 000 1868 __ 17,003,405 __ _ 1867___ 16,002,109 __ _ 1930 __ _ 69,384,837 9, 570, 400 4, 989, 655 1866 __ 15,651, 183 _ 1929 __ _ 73,828,195 10, 394, 720 3 4> 700, 000 1865 ___ 11,891,746 _ __ 1928 __ __ 75,348,069 10, 987, 200 3 4, 900, 000 1864 __ 12,538,649 __ _ 1927 __ _ 80,095,564 11, 795, 840 3 5, 300, 000 1863 __ 11,785,320 __ _ 1926 __ _ 84,437,452 11, 428, 400 3 5, 150, 000 1862 __ 9,695, 110 ___ 1925 ____ 61,817,149 8, 812, 160 3, 905, 869 9,799,654 _ _ 1924 ____ 87,926,862 12, 055, 760 4, 800, 000 1 Q9Q Q*3 33Q OOQ 13, 544, 160 3 5, 400, 000 1860 ___ 8, 115,842 __ . 1922 __ __ 54,683, 022 8, 076, 320 3 2, 100, 000 1859 __ 9,619,771 __ . 1921 ____ 90,473,451 12, 029, 620 3 4, 800, 000 1858___ 8,426, 102 __ . 1857 __ 8, 186,567 __ _ 1920 __ __ 89,598,249 13, 227, 200 5, 404, 270 1856 __ 8,534,779 __ _ 1919__ __ 88,092,201 12, 496, 960 3 5, 200, 000 1855 __ 8,141,754 __ _ 1918 ____ 98,826,084 14, 252, 000 3 5, 900, 000 1854 ___ 7,394,875 _ _ 1917 ____ 99,611,811 14, 109, 760 3 5, 050, 000 1853 __ 6,400,426 __ _ 1916 ____ 87,578,493 12, 406, 240 3 5, 200, 000 1852 ___ 6, 151,957 __ _ 1915 ____ 88,995,061 12, 046, 400 5, 365, 475 1851 __ 5,481,065 __ _ 1914 ____ 90,821,507 12, 433, 220 5, 400, 000 1913 ____ 91,524,922 12, 679, 530 3 5, 500, 000 1850 __ 4, 138,164 __ . 1912 __ __ 84,361, 598 3 12, 500, 000 3 5, 450, 000 1849 __ 3,995,334 __ . i QI 1 on 4fi4. Ofi7 3 13, 400, 000 3 5, 800, 000 1848 __ 3,805,942 __ . 1847 __ 3,551,005 __ . 1910 ____ 84,485,236 3 13, 900, 000 5, 838, 972 1846 __ 2,887,815 ____. 1QOQ Ci 070 3

TABLE 3. Average thickness and range in thickness of Llewellyn and Pottsville coal beds based on 5,030 observations [Thicknesses obtained from mining company data]

Bed thickness (feet) Coal thickness (feet) Average Member, and coal bed amoun^ of refus« Average Maximum Minimum Average Maximum Minimum (perce*rt)

Llewellyn Formation

No. 29 ______-____-_--_--._ 28______27 ______26 ______25 ______.______-_-_____-__ 24 ______3.0 3.5 0. 1 ______5.0 7.0 . 1 __ 23 ______4.0 5.0 . 1 _ 22 3.0 5.0 . 1 _ 22L ______Faust (21)______5.8 10.0 .1 4.0 6.0 0.1 31 Rabbit Hole (20) ______8.0 .1 i 2.2 6.0 .1 Tunnel (19)______3.0 8.0 .3 2.5 7.0 .1 16 Peach Mountain (18) ______8.0 19.0 .4 6.0 17.5 .3 25 Little Tracy (17) ______..._ __ 6.4 14.0 .5 4.7 14.0 .1 26 Upper Four Foot (16^) ------_ _._____ 3.8 12.0 1.0 2.9 5.3 .2 23 Tracy (16)______7.8 17.8 1.9 6.3 16.0 . 1 19 Little Clinton (15^)- - - -- _ - 4.1 . 1 1 2.0 4.1 .1 Clinton (15M)~ ___ ---- ______. i2.7 7.1 . 1 1 2.7 7.1 .1 Little Diamond (15)______4.6 8.5 1.8 2.8 4.5 .1 39 1 1.8 4.0 .1 1 1.8 4.0 . 1 Diamond (14) ______6.9 13.4 1.0 5.6 10.0 .5 19 _____ 13.8 7.8 .1 1 3.8 7.8 . 1 i 1.2 1.5 . 1 1 1.2 1.5 .1 Little Orchard (13) ______..____ 4.5 6.0 .6 i 4.5 6.0 .6 __. Orchard (12) ______._ __ 6.8 14.0 .8 5.0 12.0 .3 26 Primrose (!!)______._____ 10.0 23.3 1.5 8.4 21.0 .1 16 Holmes (10) ______._____ 8.9 3 84.7 .3 8.2 3 80.0 .1 8 Holmes Leader (10L)______1.2 . 1 i .3 1.2 .1 Lower Four Foot (9^) ______4.8 10.0 .4 3.5 5.2 .2 27 Top Split (9)______8.3 30.0 .5 7.4 30.0 .1 11 Middle Split (8^) ______8.7 41.4 .9 6.1 14.1 .1 30 8M-- - _____ 6.2 9.3 . 1 4.3 6.7 .1 31 Bottom Split (8) ______8.2 3 80.0 1.0 6.1 3 56.2 .1 25 Skidmore (7)______7.0 20.0 .4 5.4 11.5 .1 23 Skidmore Leader (7L)______3.0 6.5 . 1 1.4 2.5 .1 33 Seven Foot (6) ______5.2 19.6 .2 3.7 11.5 .1 29 Seven Foot Leader (6L) ______1.3 2.8 .2 1.3 2.8 .1 Buck Mountain (5) ______6.9 16.4 .5 4.7 12.5 .2 22

Pottsville Formation

Sharp Mountain Member Little Buck Mountain (4) _ _ _ .____ 7.0 16.0 0.1 4.1 14.0 0.1 41 Scotty Steel 3 ______.. __ 10.9 18.7 .8 8.1 12.6 .2 26 Scotty Steel 2______4.9 .1 1 1.8 4.9 .1 SchuylkUl Member Lykens Valley !______. __ 1.9 10.0 .1 1.1 10.0 .1 42 Lykens Valley 1}^______._____ 1.6 4.0 .5 1.0 2.3 . 1 37 Lykens Valley 2______9.2 14.5 .3 8.9 14.5 .3 3 Lykens Valley 3______.____ 4.2 10.4 .1 1.3 10.4 .1 69 Lykens Valley 3J^______. 1 1.4 4.3 .2 1 1.4 4.3 .2 Tumbling Run Member Lykens Valley 3^______2.1 .2 1 1.2 2.1 .2 Lykens Valley 3J^______._____ 2.1 4.0 .2 2.1 4.0 .2 Lykens Valley 4_ _ _ _ 4.4 12.0 .8 3.5 5.3 .1 20 Lykens Valley 5______. __ 9.3 23.0 .9 8.1 23.0 . 1 15 Lykens Valley 6______4.4 12.0 .1 4.2 12.0 .1 4.5 Lykens Valley 7 ______.____ 5.9 12.8 . 1 3.3 11.1 .1 34

i Thickness data concentrated in a small area and not widespread enough to 2 Data insufficient to calculate average percentage of refuse. determine adequately average thickness. 3 Thickened by structural adjustments.

316-352 O - 69 - 9 124 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLV1ANIA

LYKENS VALLEY NO. 4 COAL BED This bed has been heavily mined in the Tov^er City and The Lykens Valley No. 4, or "Whites," coal bed was Brookside mines of the Tower City quadrangle (Wood mined intensively west of Goodspring in the Donaldson and Trexler, 1968b, sheet 1). Large-scale mining appar­ syncline (Wood and Trexler, 1968b, sheet 3; 1968c, ently has been unprofitable elsewhere.

sheets 1, 3) and west of Rausch Creek in the Dauphin LYKENS VALLEY NO. 2 COAL BED and Lorberry synclines and the Joliet and Georges Head anticlines (Wood and Trexler, 1968b, sheet 4; The Lykens Valley No. 2 coal bed has been recognized 1968c, sheet 2). In these areas this bed averages about throughout the area, except on Sharp Mountain in the 4.4 feet thick and contains an average thickness of 3.5 eastern part of the Minersville quadrangle and on Big feet coal (table 3). Lick Mountain west of Wiconisco in the Lykens quad­ Many small mines, trenches, strip pits and prospect rangle (Wood and Trexler, 1968b, sheet 2; 1968c, sheet pits have been opened on the Lykens Valley No. 4 coal 3). bed east of the area of intensive mining. The bed de­ The Lykens Valley No. 2 is the thickest coal bed of creases rapidly in thickness eastward and is not com­ the Schuylkill Member and averages 9.2 feet thick in mercially minable east of the west border of the Miners- the western part of the area; 8.9 feet is coal (table 3). ville quadrangle (Wood and Trexler, 1968b, sheet 1). It reaches a maximum thickness of about 14.5 feet in The Lykens Valley No. 4 coal bed is commonly over­ the Brookside mine (Wood and Trexler, 1968c, sheet lain and underlain by conglomerate and sandstone, but 1). The bed thins east and northeast from the Penag locally, the enclosing rocks are shale and siltstone. The mine in the Tremont quadrangle and is too thin to mine coal generally consists of bands of vitrain, bright at- profitably in the northern part of the Minersville quad­ trital, impure, and dull attrital coal, which range in rangle (Wood and Trexler, 1968b, sheets 1, 3). thickness from % to 1 inch. Thin partings of claysitone In its few exposures the Lykens Valley No. 2 coal bed and shale are common. consists of alternating % to 1 inch bands of vitrain, Much of the coal produced in the Lykens and Tower bright attrital coal, impure coal, and dull attrital coal. City quadrangles was extracted from the Lykens Valley The refuse in the bed averages about 3 percent, which No. 4 coal bed at the Short Mountain, Big Lick, Wil- is much lower than the refuse percentages determined liamstown, Brookside, Tower City, Valley View, and for any other bed (table 3) . Porter mines. Workings on this bed extended to nearly At about half the localities where the Lykens Valley 2,200 feet below sea level in the Williamstown mine. No. 2 coal bed has been mined, the floor is shale and siltstone. Conglomerate and sandstone foms the floor COAL BEDS OF THE SCHUYLKILL MEMBER OF THE at all other places. The roof is predominantly conglo­ POTT8VILLE FORMATION merate and sandstone, but in the Brookside and Tower Four rather persistent coal beds have been recognized City mines it is shale. in the Schuylkill Member, and a fifth iionpersistent bed has been mapped locally. From the base up, these are the LYKENS VALLEY NO. COAL BED Lykens Valley Nos. 3i/£, 3, 2,1%, and 1 coal beds. Other The Lykens Valley No. iy2 coal bed has been recog­ nonpersistent coal beds are shown on the graphic sec­ nized throughout the area, except in the noHhern parts tions of the member (pis. 1-3), but are not shown on the of the Swatara Hill and Tremont quadrangles and the coal maps (Wood and Trexler, 1968b, c) because they Minersville quadrangle (Wood and Trexler, 1968b, are less than 1.2 feet thick. The stratigraphic position of sheets 1-3) . This bed averages 1.6 feet thick and reaches these four persistent beds and the local coal bed are a maximum thickness of 4.0 feet (table 3) in the Tower briefly described in the section on the Schuylkill Mem­ City mine (Wood and Trexler, 1968c, sheet 1). It has ber. The nonpersistent Lykens Valley No. 3^ coal bed been exploited, by numerous small mines and exposed is not described hereafter. in many trenches and prospect pits, but it is not con­ sidered to be minable under present economic conditions. LYKENS VALLEY NO. 3 COAL BED The Lykens Valley No. 3 coal bed has been mined and LYKENS VALLEY NO. 1 COAL BED prospected at many localities in the area, but it has not The Lykens Valley No. 1 coal bed lies 5 to 50 feet been identified in the eastern part of the Minersville below the top of the Schuylkill Member and has been quadrangle on Broad and Sharp Mountains (Wood and exposed at many small mines, prospect pits, and Trexler, 1968b, sheets 1, 2). It is commonly overlain trenches throughout most of the area. The average and underlain by conglomerate and sandstone and aver­ thickness is 1.9 feet (table 3), and the co^.l has been ages 4.2 feet thick, of which 1.3 feet is coal (table 3). worked extensively only in the Lincoln mine (Wood and ECONOMIC GEOLOGY 125 Trexler, 1968b, sheet 4), where the bed reaches a maxi­ is absent or thin in the Peaked Mountain anticline and mum thickness of 10.0 feet, of which 4 to 6 feet is good Little Mountain syncline in the Tremont quadrangle coal. (Wood and Trexler, 1968b, sheet 3), is not known on the Where exposed, the Lykens Valley No. 1 coal bed is limbs of the Joliet anticline and Tremont syncline in almost invariably intensively fractured and consists of the Pine Grove and Tower City quadrangles (YTood a mass of "shelly" coal in which all evidence of original and Trexler, 1968b, sheet 4; 1968c, sheets 1, 2), and bedding has been obliterated. This fracturing suggests thins out westward in the central and western parts of that the bed was the site of much differential bedding- the Lykens quadrangle (Wood and Trexler, 1968c, sheet plane movement that resulted from structural adjust­ 3). Its average thickness is 10.9 feet, of which 8.1 feet is ments in incompetent beds between the competent sand­ coal (table 3). A maximum thickness of 18.7 feet is stones and conglomerates of the Schuylkill and Sharp recorded in the Goodspring mine (Wood and Trexler, Mountain Members. 1968b, sheet3). At most places the Lykens Valley No. 1 coal bed is The No. 3 coal bed is a banded anthracite com]: osed too thin and fractured to mine under present economic of alternating layers of vitrain, bright attrital coal, im­ conditions. pure coal, dull attrital coal, and partings of siltrtone

COAL BEDS OF THE SHARP MOUNTAIN MEMBER OF THE and claystone. Individual layers are % inch to 1 inch POTTSVILLE FORMATION thick and average about y2 inch. The Scotty Steel No. 3 coal bed was anisidentified and The Scotty Steel Nos. 2 and 3 coal beds of the Sharp mined as the Buck Mountain coal bed of the Llewellyn Mountain Member are recognized over much of the Formation at several localities south of the Mine Hill area, and the overlying Little Buck Mountain (No. 4) fault complex. At these localities the Buck Mountain coal bed is known in the northern part of the area in is thin and impure, and the Scotty Steel is thick and the Minersville and Tremont quadrangles (Wood and relatively clean. Misidentification was most common Trexler, 1968b, sheets 1-3). Several other nonpersistent in mines near Donaldson, in mines in the Dam syncline, coal beds are shown on the graphic sections (pis. 1-3), and at places between Donaldson and the synclir*} in but are not shown on the coal maps because of their Tremont quadrangle (Wood and Trexler, 1968b, rheet thinness. 3). The Buck Mountain is thick and has been irten- SCOTTY STEEL NO. 2 COAL BED sively mined north of the complex, whereas the Scotty The Scotty Steel No. 2 coal bed is present throughout Steel is thin or absent. South of the complex, the Buck the area, except east of the Penag mine in the south- Mountain is thin, and the Scotty Steel is thick and has central part of the Tremont quadrangle and on Sharp been intensively mined. Before this survey, the thick Mountain in the Tower City, Pine Grove, Swatara Hill, Buck Mountain north of the complex had been mircor- and Minersville quadrangles (Wood and Trexler, 1968b, related southward with the thick Scotty Steel. sheets 2-4; 1968c, sheet 2). It averages 1.8 feet thick (table 3) and reaches a maximum of 4.9 feet in Penag LITTLE BUCK MOUNTAIN (NO. 4) COAL BED mine, but it is too thin to be commercially exploited at The Little Buck Mountain (No. 4) coal bed is rec­ most places in the foreseeable future. ognized only in the Tremont and Minersville quad­ The floor and roof rocks of the Scotty Steel No. 2 rangles (Wood and Trexler, 1968b, sheets 1-3). North coal bed vary from place to place, but the floor is pre­ of the Mine Hill fault complex it underlies the Heck- dominantly sandstone and conglomerate, and the roof schersville, Jugular, Little Mountain, and Rohres^ille is most commonly shale. Coarse conglomerate, which synclines, the south limb of the Powder Hill anticline, composes the bulk of the middle and lower parts of the and the limbs and crests of the Peaked Mountain and Sharp Mountain Member, generally lies a few inches to Mine Hill anticlines. South of the fault complex it crops a few feet below the coal bed. This stratigraphic rela­ out on the limbs of the Dam and Forestville synclines tionship was a great aid in tracing the coal beds of the and Crystal Run anticline and thins out southwestv^ard upper part of the member and the lower part of the in the northeastern part of the Tremont quadrangle. Llewellyn Formation. The No. 4 is the uppermost coal bed of the SI ^r,p Mountain Member and commonly lies less than 20 feet SCOTTY STEEL NO. 3 COAL BED below the Buck Mountain coal bed of the Llewellyn The Scotty Steel No. 3 coal bed, which has been mined Formation. Locally, however, it is as much as 50 feet at many places in the area, lies stratigraphically 8 to below. Its thickness averages about 7.0 feet, contahr an 100 feet below the Buck Mountain (No. 5) coal bed. It average of 4.1 feet coal (table 3), and reaches a maxi­ thins out eastward on Sharp Mountain in the Miners­ mum thickness of about 16.0 feet in the Pine Fnot ville quadrangle (Wood and Trexler, 1968b, sheet 2), mine (Wood and Trexler, 1968b, sheet 1). On the flunks 126 GEOLOGY, SOUTHEKN ANTHRACITE FIELD, PENNSYLVANIA and crest of the Mine Hill anticline, the Little Buck BUCK MOUNTAIN (NO. 5) COAL BED Mountain is divided into two benches called the Bottom The Buck Mountain (No. 5), also known as the Split (4B) and the Top Split (4T) (Wood and Trexler, 1968b, sheet 1). Twin or Umbahauer, coal bed has been cf consider­ able economic importance in the area. Although it is Conglomerate, sandstone, siltstone, and shale each less than 2 feet thick at some places, this bod has been constitute the roof and floor in about an equal number traced throughout the area. Its average thickness is 6.9 of places, but the roof is mainly shale and siltstone where feet, of which 4.7 feet is coal (table 3). A. maximum the Little Buck Mountain is less than 15 feet below the thickness of 16.4 feet is reached in the Pin^ Knot and Buck Mountain coal bed. Thomaston mines (Wood and Trexler, l;96£b, sheet 1). The Little Buck Mountain coal bed has been inten­ At most places the Buck Mountain bed i^ composed sively exploited in many of the large and small under­ mainly of bright attrital coal with thin 1/16 to y2 inch ground mines in the Jugular, Heckscherville, Little layers of vitrain and dull attrital coal. Bory layers of Mountain, and Rohresville synclines and on the Mine coal are common near the base of the bed and in the Hill, Peaked Mountain, and Crystal Kun anticlines. upper 1 foot. The bed is dirty and has been rnprofitable It has also been extensively strip mined on the crest and to work in the vicinities of the Penag, Goodspring, upper flanks of the Mine Hill anticline. Joliet, Westwood, New Lincoln, Lincoln, and Tower

GOAL BEDS OF THE LLEWELLYN FORMATION City mines. The Buck Mountain commonly rests on a fissile to Several hundred million tons of anthracite have been nonfissile coaly shale sequence 0 to about 1C feet thick. extracted from the Llewellyn Formation in the area. Of Where this shale is absent, the coal rests directly on the 52 coal beds that have been mined, 38 beds are in this the uppermost sandstone or conglomerate of the Sharp formation. The more productive of these beds are the Mountain Member of the Pottsville Formation. For Bottom Split (No. 8), Middle Split (No. 8V2 ), and Top example, at many places along Sharp Mountain in Split (No. 9) coal beds of the Mammoth coal zone. Less the Minersville quadrangle (Wood and Trexler, 1968b, productive coal beds are the Buck Mountain (No. 5), sheet 2), the coal of the Buck Mountain bed is in con­ Skidmore (No. 7), Holmes (No. 10), Primrose (No. tact with the upper coarse conglomerate of tt at member. 11), Orchard (No. 12), Little Orchard (No. 13), Dia­ Locally, the shale at the base of the Bucl- Mountain mond (No. 14), Tracy (No. 16), Little Tracy (No. IT), contains numerous fossil plant impressions, and at other and Peach Mountain (No. 18). The Seven-Foot Leader places, Stigmaria impressions are common. (No. 6L), Seven Foot (No. 6), Skidmore Leader (No. The Buck Mountain is the lowest commercially work­ 7L), No. 8%, Lower Four Foot (No. 9%), Holmes able coal bed in the Llewellyn Formation. It has been Leader (No. 10L), Little Diamond (No. 15), Upper previously miscorrelated with the Scotty k0teel No. 3 Four Foot (No. 16y2 ), Tunnel (No. 19), and Eabbit coal bed in mines near Donaldson, in mines in the Dam Hole (No. 20) coal beds have been mined at many places, syncline, and in the intervening area (Wood and but have been of much less economic importance. The Trexler, 1968b, sheet 3). (See Scotty Steel No. 3 coal bed Diamond Leader (No. ML), No. 14y2, No. 15K, Clinton for a more complete description.) In addition, it was (No. 151,4), Little Clinton (No. 151/2), and Faust (No. mined as the Skidmore (No. 7) coal bed in the Williams- 21) coal beds have been prospected at many places, but town, Big Lick, and Short Mountain mines (Wood and except for local thick pods of coal, have been of little Trexler, 1968c, sheet 3). economic importance. The 22, 22L, 23^, 24, 25, 26, 27, About 300 thickness measurements, made largely by 28, and 29 coal beds, which lie above the Faust bed in the employees of mining companies, indicate thp,t the Buck upper part of the Llewellyn, crop out in small parts of Mountain is thinnest in the Brookside, Tower City, and the area, generally are variable from place to place in Valley View mines (Wood and Trexler, 196rrt,, sheet 1). purity and thickness, and have been little prospected It increases gradually in thickness toward tt e northeast or mined. Other coal beds are locally recognized in the from an average of about 4.0 feet in there mines to Llewellyn, but are too thin and too limited in areal about 7.8 feet in the Heckscherville syncline and to­ extent to be of economic importance. ward the west to about 5.8 feet near Wisconisco (Wood Only those coal beds that have been of economic im­ and Trexler, 1968b, sheet 1; 1968c, sheet 3). Similarly, portance because of production or of stratigraphic im­ the average thickness of the coal in the bed increases portance because of widespread occurrence are described from about 3.0 feet in these mines to 5.5 feet in the Heck­ below. scherville syncline and 4.1 feet near WisconisTO. ECONOMIC GEOLOGY T.27

SEVEN FOOT (NO. 6) COAL BED or Barclaugh bed on Sharp Mountain and as the E\lly Best bed at places in the Heckscherville syncline (Wood The Seven Foot (No. 6) coal bed has been recognized and Trexler, 1968b, sheets 1, 2). throughout the area, except between Swatara Creek and the Colket mine and east of the Blackwood mine on BOTTOM SPLIT (NO. 8) COAL BED Sharp Mountain (Wood and Trexler, 1968b, sheets 2, 3). Elsewhere, this bed averages 5.2 feet thick, of which The most widely mined coal bed in the area is the 3.7 feet is coal. It reaches its maximum thickness of 19.6 Bottom Split (No. 8) bed of the Mammoth coal zone; feet in the Tower City mine (table 3). The average and however, the tonnage produced may not exceed that ex­ maximum thicknesses were derived from about 150 tracted from the Middle Split (No. 8y2 ) and Top Split measurements, largly made by employees of mining (No. 9) coal beds. companies. The Seven Foot coal bed has not been as Locally, the Bottom Split is less than 1.2 feet thick intensively mined as have the adjacent coal beds in the in small areas, but the outcrop of the bed is shown ap be­ Llewellyn. ing continuous on the coal and geologic maps and the SKIDMORE (NO. 7) GOAL BED structure sections (GQ-689, 690, 691, 692, 698, 699, 701; Wood and Trexler, 1968b, c). The Skidmore (No. 7) coal bed has been mined in­ The Bottom Split has been mined under a variety tensively and has been of considerable economic im­ of names. Principal among these names are the Daniel or portance. It is less than 1.2 feet thick in the vicinity of Jugular beds in the Heckscherville syncline, the Black- Middle Creek (Wood and Trfexler, 1968b, sheet 3), but heath bed south of the Mine Hill anticline, the White elsewhere averages 7.0 feet, of which 5.4 feet is coal Ash, Big Dirt, Heister, or Barclaugh beds on SI arp (table 3). The Skidmore attains a maximum thickness Mountain, the No. 9 1/2 beds in the Lykens quadrangle of about 20.0 feet in Thomaston mine (Wood and Trex­ (Wood and Trexler, 1968b, sheets 1, 2, 4; 196'8c, sheet ler, 1968b, sheet 1). The average and maximum thick­ 3), and the Mammoth bed at many places throughout nesses were obtained from about 400 measurements the area. made largely by employees of mining companies. The At most places the Bottom Split is underlain and Skidmore bed is relatively dirty and impure at the overlain by shale or siltstone. The roof shale commonly Colket, Middle Creek, Goodspring, Joliet, Westwood, contains a well-preserved fossil flora, and the floor sHale and Lincoln mines. usually contains impressions of Stigmaria, plant The Skidmore is a banded anthracite that commonly branches, tree trunks, and numerous ironstone concre­ consists, from the top down, of a 4- to 12-inch bench tions that range in diameter from about 1/2 inch to of interbedded layers of bright attrital coal and vitrain; 3 feet. a 6- to 15-inch bench of dull attrital coal, impure coal, The Bottom Split coal bed averages 8.2 feet thick and or bone, a 6- to 24-inch bench of bright attrital coal con­ contains an average of 6.1 feet of coal (table 3). It taining thin lenses of vitrain, an 8- to 30-inch bench of reaches a maximum structurally deformed thickners of bright attrital coal and vitrain interbedded in 2-to 5- about 80.0 feet in the Pine Knot mine in the upper plate inch layers, an 8- to 30-inch bench of vitrain, a 6- to of Jugular fault (Wood and Trexler, 1968b, sheet 1). 18-inch bench of dull attrital coal, and a basal bench The stratigraphic thickness near this locality generally of 2 to 10 inches of bright attrital coal. is about 20.0 feet, and the 80.0 foot thickness is the Locally, the Skidmore and Bottom Split (No. 8) coal result of disharmonic folding, plastic flow, and fracture bed are close together. In the Buck Run mine on the flow as the bed was dragged against the lower plate of (north limb of the Eohresville syncline (Wood and the Jugular fault. The average and maximum tlick- Trexler, 1968b, sheet 1), these coal beds almost merge nesses were determined from about 500 measurements at the surface, and underground mining records indicate largely obtained from mined records. The local average either that they merge or are so close that they were thickness of the Bottom Split gradually increases east­ mined together. However, at most (places 40 to 50 feet of ward from 2.5 feet in the Lykens quadrangle to 11.0 feet rock separates these coal beds, and the maximum strati- in the eastern part of Minersville quadrangle (Wood graphic separation is slightly more than 120 feet near and Trexler, 1968b, sheet 1; 1968c, sheet 3). the John Veith shafts (Wood and Trexler, 1968b, sheet At the few localities where the Bottom Split could 2). be examined, it is a banded anthracite consisting, from The Skidmore coal bed was mined as the Top Split the top down, of the following sequences: 10 to 28 (No. 9) coal bed in the Williamstown, Big Lick, and inches of bright attrital coal containing vitrain layers Short Mountain mines (Wood and Trexler, 1968c, sheet 1/16 to 1/2 inch thick, 8 to 18 inches of bright attrital 3). It has been locally mined as the White Ash, Dirt, coal containing local partings of bone or impure coal, 128 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLV1ANIA

15 to 28 inches of bright attrital coal and thin laminae of TOP SPLIT (NO. 9) GOAL BED vitrain, 6 to 14 inches of dull attrital coal, and 20 to The Top Split (No. 9) coal bed has beer one of the 42 inches of bright attrital coal containing many thin principal sources of anthracite and is recognized laminae of vitrain. Locally, fusain layers as much as throughout the area. Stratigraphically, it is important one-sixteenth inch thick are present in the lower 20- because it is the uppermost bed of the Llewellyn Forma­ to 42-inch bench. tion that has been intensively mined in almost all the

MIDDLE SPLIT (NO. 8j) COAL BED large mines in the area. In the Heckscherville syncline it was known as the Crosby bed (Wood and Trexler, The Middle Split (No. 8%) coal bed of the Mammoth 1968b, sheet 1). South of the Mine Hill anticline it was coal zone has been one of the principal sources of anthra­ called the White Ash, or Four Foot, bed, and on Sharp cite in the area. It has not been so widely mined as the Mountain it was known variously as the P:tch, Dan's, Bottom Split coal bed, but it has been worked much Dirt, Barclaugh, and White Asih beds (Wood and Trex­ more intensively at a number of large mines. The Mid­ ler, 1968b, sheets 1,2). In the Lykens quadrangle it was dle Split has been traced throughout the area, except mined as the Primrose (No. 11) bed (Wood and Trex­ where it merges into the Top Split (No. 9) coal bed ler, 1968c, sheet 3). In addition, at many places where from a point near the west border of Minersville quad­ the Top Split is exceptionally thick, it has been known rangle to near Blackwood mine (Wood and Trexler, as the Mammoth bed. 1968b, sheet 2), and except where it is combined with The roof and floor rock of the Top Split is commonly the Bottom Split coal bed for a distance of about 500 shale and siltstone, but locally, conglomerate and sand­ feet near the east border of the same quadrangle (Wood stone rest directly on the coal bed (pis. 1-3). Generally, and Trexler, 1968b, sheet 1). the roof rock contains a well-preserved fossil flora, and The Middle Split has been mined under a variety of the floor rock contains numerous Stigmaria impressions. names in the area. In the Heckscherville syncline it The Top Split coal bed averages 8.3 feet thick, of was known as the Lelar bed, and south of the Mine Hill which 7.4 feet is coal (table 3). The maximum thick­ anticline it was mined as the Middle Branch and Seven ness is about 30.0 feet in Pine Knot mine (Wood and Foot bed (Wood and Trexler, 1968b, sheet 1). On Sharp Trexler, 1968b, sheet 1). The average and maximum Mountain in the Pine Grove and Tower City quad­ thicknesses of the Top Split were obtained from about rangles (Wood and Trexler, 1968b, sheet 4; 1968c, sheet 600 measurements largely made by mining company 2), it has been called the Big Dirt, White Ash, Four employees. The bed gradually thins southweptward and Foot, and Barclaugh bed, and in the Lykens quadrangle southward from an average thickness of about 11.2 feet (Wood and Trexler, 1968c, sheet 3) it was mined as the in the Heckscherville syncline (Wood ard Trexler, Holmes (No. 10) bed. At many places it was known 1968b, sheet 1) to an average thickness of 4.8 feet in simply as the Mammoth bed. Shale and siltstone generally are the floor and roof the western and southern parts of the area. E,efuse aver­ rocks of the Middle Split, but from the vicinity of New ages about 11 percent of the bed, which is considerably Mines to the Colket mine (Wood and Trexler, 1968b, less than the refuse content of the other coal beds in the sheets 2, 3), the bed is overlain by a coarse pebble and Mammoth coal zone (table 3). Despite this low refuse cobble conglomerate that resembles the basal con­ content and the high average thickness, the Top Split glomerate of the Sharp Mountain Member of the Potts- coal bed has not been as important commercially as ville Formation. either the Middle or Bottom Splits. The Middle Split averages 8.7 feet thick and contains At a few localities where the Top Split was exposed, an average of 6.1 feet of coal (table 3). It reaches a it was a bright banded anthracite, which consisted from maximum thickness of 41.4 feet in Colket mine (Wood the base up of a 1- to 3-foot unit of bright sttrital coal and Trexler, 1968b, sheet 3). The average and maximum containing thin layers of impure coal or bone near the thicknesses are from about 400 measurements that were base, a 2- to 4-foot unit of vitrain containing thin lam­ largely obtained from mine records. The bed thins in all inae of fusain, and a 2- to 4-foot unit of bright attrital directions from the Colket mine, but thins less rapidly coal containing %- to i^-inch layers of vitr^.in. to the northeast than in other directions. Where observed, the Middle Split coal bed is a banded HOLMES (NO. 10) COAL BED anthracite consisting of thin to thick layers of bright attrital coal, vitrain, dull attrital coal, and impure coal. The Holmes (No. 10) coal bed has been ar important Locally, thin layers of fusain are scattered throughout source of anthracite throughout the area. It was mined the bed, and benches of bony coal are present in the as the Church bed in the Heckscherville syncline, as the upper and lower parts. Black Heath bed in the vicinity of Donaldscn and Tre- ECONOMIC GEOLOGY 129 mont, as the Pat Martin, Little Orchard (No. 12), or feet thick, of which 8.4 feet is coal (table 3). A maxi­ Twin bed in the Lykens quadrangle, as the No. 1 or mum thickness of 23.3 feet is recorded in the Thom^«ton Peacock bed on Sharp Mountain, and as the Black Mine mine (Wood and Trexler, 1968b, sheet 1). The average bed near Silverton (Wood and Trexler, 1968b, sheets and maximum thicknesses were obtained from about 1-4; 1968c, sheets 2,3). 600 measurements, made largely by employees of mining The Holmes bed averages 8.9 feet thick, of which 8.2 companies. Refuse averages 16 percent (table 3) in the feet is coal (table 3). The maximum recorded thickness Primrose, which is rather low for the coal beds cf the is about 84.7 feet in the trough of Heckscherville syn- Llewellyn Formation. This bed probably would have cline (Wood and Trexler, 1968b, sheet 1). This enor­ been the most intensively mined coal if it had underlain mous thickness, the greatest recorded for any coal bed a larger part of the area and if it had been closer s^.rati- in the area, was caused by structural flowage and dis- graphically to the other important sources of anthr^-cite. hannonic flexing of coaly material towards the trough At most localities the Primrose is rather clean anc?, has during folding. On the limbs of the syncline this bed been considered extremely desirable for mining o^iera- averages about 12.0 feet thick; thus, the thickness of the bed has been increased about seven times in the trough. tions, but at the East Franklin and Goodspring mines it The Holmes averages 10.5 feet thick in the northern is dirty (Wood and Trexler, 1968b, sheets 3, 4). part of the Minersville quadrangle, 9.0 feet in the south­ Shale is the principal floor rock of the Primrose coal ern part, 10.6 feet in the southern part of the Tremont bed. It commonly contains impressions of .Stigmarfji or quadrangle, 9.4 feet in the Tower City and Pine Grove a well-preserved fossil leaf flora. Shale is also the prin­ quadrangles, and 4.2 feet in the Lykens quadrangle cipal roof rock, but locally either conglomerate or rand- (Wood and Trexler, 1968b, sheets 1-4; 1968c, sheets stone prevail. A pebble conglomerate overlies the F^m- 1-3). The average and maximum thicknesses for the rose at many places in the Minersville, Tremont, and area and for specific parts were obtained from about Pine Grove quadrangles (Wood and Trexler, 1968b, 400 measurements from mining company records. sheets 1-4). Conglomerate, shale, and sdltstone are the principal The Primrose coal bed is a banded anthracite that roof rocks of the Holmes coal bed, with shale pre­ consists of alternating thin to thick layers of bright dominating slightly. Sandstone is present at many places, but is not so common as are the other three. attrital coal, dull attrital coal, vitrain, and thin laminae Shale is the chief floor rock. Abundant fossil leaves are of f usain. The upper and lower parts of the bed contain preserved at many places in the roof shale, and well-pre­ considerable amounts of bony or impure coal at nany served impressions of Stig-maria are common in the places. floor shale. The Primrose has been of great economic and strati- The Holmes is a banded anthracite, which consists of graphic importance because it is the uppermost coal thin to thick layers of vitrain interbedded with similar bed in the Llewellyn Formation that has been widely layers of bright attrital coal, dull attrital coal, and bone. mined. The Diamond (No. 14), Tracy (No. 16), and Impure coal or bone generally is concentrated in the Peach Mountain (No. 18) coal beds also have been lower and upper few inches of the bed. mined intensively; but as their outcrop areas are con­ Refuse averages 8 percent in the Holmes coal bed siderably smaller, they have not been as valuable for (table 3), which is less than that determined for the stratigraphic correlations and structural interpre­ other coal beds of the Llewellyn Formation. Consider­ tations. ing the great average thickness of the Holmes and the OBCHAED (NO. 12) COAL BED low refuse content, it is difficult to understand why this bed was not the most heavily mined bed in the area; The Orchard (No. 12) or lower split of the Twin coal however, Smith (1895, p. 2111,2122,2131) reported that bed has been widely recognized and intensively mined the Holmes was a rough and dirty bed that is locally locally. At most places, however, this bed is dirty and variable in thickness and purity. Despite the low aver­ variable in thickness. It averages 6.8 feet thick, of which age amount of refuse, the coal itself apparently con­ 5.0 feet is impure coal (table 3), and reaches a maximum tains much ash, which has adversely affected the com­ thickness of 14.0 feet in workings of the East Frarklin mercial value and mining. mine (Wood and Trexler, 1968b, sheet 4). Because of PBIMEOSE (NO. 11) COAL BED the variable thickness, included impurities, and dirtr the The Primrose (No. 11) coal bed has been traced Orchard coal bed has been of limited economic impor­ throughout the central part of the area and has been one tance, and it does not seem likely that its relative im­ of the principal sources of anthracite. It averages 10.0 portance will be different in the future. 130 GEOLOGY, SOUTHERN ANTHRACITE TTELD, PENNSYLVANIA LITTLE: OBCHABD (NO. 13) COAX BED Refuse averages 19 percent; but at many places the The Little Orchard (No. 13) or upper split of the coal itself is impure, and the bed has not be^n mined so Twin coal bed has been mined at many places, but gen­ intensively as have the underlying beds. The average erally is too thin and dirty to be mined profitably. This and maximum thicknesses were determined from about bed and the Orchard merge in many localities into a sin­ 150 measurements largely made by mining company gle bed that is shown on the maps and illustrations of employees. There is little information con"«rning the this report as the Orchard. The Little Orchard averages bed in the western and southern parts of tl ^ area; but about 4.5 feet in the Tremont and Minersville quad­ locally in these parts, the bed has been squeezed by rangles and reaches a maximum thickness of about 6 adjacent more competent strata so that tH thickness feet in the Lytle and Oak Hill mines (Wood and Trex- is highly variable and the coal is commonly shelly. ler, 1968b, sheets 1-3). It has been, and probably will Shale and sandstone are the dominant roof rocks, and be, of little economic importance. shale is the principal floor rock. A large assemblage of fossil plant leaves commonly is present in the roof DIAMOND (NO. 14) COAL BED rock. The Diamond (No. 14) coal bed has been mined at The Tracy is a banded anthracite that consists of many places, but it has not been so important as the thin to thick layers of vitrain, bright attrital coal, dull underlying more heavily mined coal beds because of its attrital coal, and impure coal or bone. Thin laminae limited areal extent. It averages 6.9 feet thick, of which of fusain are common at many places. At the Salem 5.6 feet is coal (table 3). It reaches a maximum thick­ mine near Silverton, the Tracy coal bed WTS mined as ness of 13.4 feet in the Phoenix and Lytle shafts (Wood the Tunnel coal bed, and north of the towr of Miners­ and Trexler, 1968b, sheets 1,2). The bed thins gradually ville it was mined as the Cockle bed (Wood pnd Trexler, from these shafts southwestward to an average thick­ 1968b,sheet2). ness of about 4.0 feet in tne Tremont quadrangle, thick­ LITTLE TRACT (NO. 17) COAL BED ens to an average of 10.0 feet in the Tower City quad­ rangle, and thins to about 5.0 feet in the Lykens quad­ The Little Tracy (No. 17) coal bed has been mined rangle (Wood and Trexler, 1968b, sheet 3; 1968c, sheets at many places in the area. It averages alout 6.4 feet 1-3). Southward from the shafts the Diamond main­ thick, of which 4.7 feet is usually clean corl (table 3). tains an average thickness of about 6.5 feet. The aver­ A maximum thickness of about 14 feet was recorded in age thickness, the thickness in specific parts of the area, workings of the John Veith shafts (Wood and Trexler, and the maximum thickness are based upon about 100 1968b, sheet 2). Locally, this bed has been mined inten­ measurements obtained largely from mining records. sively south of the Eed Mountain fault, ^hich aided Generally, the Diamond is variable in quality and pu­ greatly hi correlating this and other beds between the rity, but in the vicinity of Forestville (Wood and Trex­ vicinities of Llewellyn and Tremont (Wooi and Trex­ ler, 1968b, sheets 1, 2) it is exceptionally clean and was ler, 1968b, sheets 2-4). The Little Tracy has been of mined intensively. economic value in limited areas and probaHy will con­ At most localities the floor and roof of the Diamond tinue to be of value in places where it h^s not been coal bed are shale and siltstone, but locally, the roof is intensively mined. fine pebble conglomerate. Plant fossils generally are ab­ PEACH MOUNTAIN (NO. 18) COAL BED sent or are poorly preserved in the floor and roof shales. The Diamond coal is a banded anthracite that com­ The Peach Mountain (No. 18) is the best known coal monly consists of thin layers of vitrain, bright attrital bed in the middle part of the Llewellyn Formation and coal, dull attrital coal, bone, and thin, laminae of fu- is the uppermost intensively mined bed in the forma­ sain. Bone is generally concentrated in the lower and tion. Its thickness is relatively uniform, averaging 8 upper few inches of the bed. feet, of which 6 feet is usually clean coal (table 3). A maximum thickness of about 19 feet is recorded in TRACT (NO. 16) COAL BED workings from the John Veith shafts (Woe d and Trex­ The Tracy (No. 16) coal bed has been worked at ler, 1968b, sheet 2). The average and maximum thick­ many of the mines that had workings in coal beds in the nesses are from about 150 measurements obtained large­ middle part of the Llewellyn Formation. In the central ly from mining records. and eastern parts of the area it averages 7.8 feet thick, The Peach Mountain has been mined und^r numerous of which 6.3 feet is coal (table 3). The bed reaches a names, principally as the Spohn, Lewis, Black Mine, maximum thickness of about 17.8 feet in workings of the and Grate coal beds. The outcrop pattern of this multi- Middle Creek mine (Wood and Trexler, 1968b, sheet 3). named bed is intricate, and the strip pits on it in the ECONOMIC GEOLOGY 131 central part of the coal field clearly outline many anti­ ranges from about 0.5 to 2.0 percent and averages clines >and synclines. Workings on this bed and on the slightly less than 0.7. Variations in ash and sulfur con­ Tracy (No. 16) and Little Tracy (No. 17) coal beds tent are unrelated to the rank of the coal. south of Red Mountain aided in correlating the strata Calorific value ranges from 10,640 to 14,130 Btu on of the middle part of the Llewellyn from near Tremont an as-received basis and from 14,730 to 15,500 Btu en a to Silverton (Wood and Trexler, 1968b, sheets 2-4). dry-mineral-matter-free basis. On an as-received b^sis The roof and floor rocks of the Peach Mountain the coal has an average heat value of 12,650 Btu and coal bed are principally shale and siltstone. An abun­ on a dry-minneral-matter-free basis, 15,170 Btu. The dant fossil plant assemblage is commonly preserved in heat value of semianthracite generally exceeds that of these rocks. Examination of this assemblage by C. B. anthracite of similar ash content by several hundred Kead and Sergius Mamay (oral commun., 1956-58) in­ Btu. dicates that the Peach Mountain is probably of early Late Pennsylvanian age and that it probably correlates Moistures averages about 4.2 percent and ranges from with the upper part of the Allegheny Formation or the a minimum of 0.9 percent in semianthracite beds of the lower part of the Conemaugh Formation of western Pottsville Formation in the East Brookside mine to a Pennsylvania. maximum of 7.9 percent in anthracite beds of the Llew­ The Peach Mountain is a banded 'anthracite con­ ellyn Formation near Zerbe. The reason for the increase sisting of thin to thick layers of bright attrital coal and in moisture content in anthracite is not known. vitrain with thinner layers of dull attrital coal and On a moisture-and-ash-free basis, hydrogen rarges impure coal or bone. from 'a minimum of 2.3 percent in anthracite to a maxi­ Because of its thickness and purity the Peach Moun­ mum of 3.8 in semianthracite and averages 2.9 for all tain probably would have rivaled any split of the Mam­ coal. Similarly, nitrogen ranges from 0.7 percent in moth coal zone in productivity if it had underlain a anthracite in the eastern part of the area to 1.5 in semi- larger part of the area. anthracite in the western part and averages about 1.1. CHARACTERISTICS OF THE COAL Oxygen ranges from 1.1 percent in anthracite to 4.1 in PHYSICAL PROPERTIES semianthracite and averages about 2.3.

The anthracite and semianthracite of the area are in TABLE 4. Physical properties of semianthracite and antrhacite from general distinguishable by their physical properties. the west-central part of the Southern Anthracite field The properties of each are perhaps best compared in table 4, which has been modified and expanded from Property Anthracite Semianthracite a table published by Turner (1934, p. 332). Luster _ _ _ Vitreous to dull_____ Vitreous to dull. Semianthracite is most easily distinguished from Structure. Laminated to amor­ Laminated to anror- phous, laminations phous laminations, anthracite in the field by its tendency to break along commonly ob­ generally distirot prismatic and rectangular fractures rather than along scured because of because of con­ uniformity of trasts in luster. conchoidal fractures. It is also generally much dirtier luster. when handled. Fracture. Predominantly con­ Predominantly rec­ choidal, but locally tangular and CHEMICAL COMPOSITION prismatic and rec­ prismatic, rarely tangular, usually conchoidal, com­ The coal of the area is of semianthracite and anthra­ widely spaced. monly closely spaced. cite rank, according to analyses of the U.S. Bureau of Streak____. Chiefly black. Chiefly black. Mines and to specifications of the American Society for Hardness. _ _. 2.75-3.00__ 2.50-2.75. True specific 1.50-1.75__ 1.45-1.55. Testing Materials (1954). On a dry-mineral-matter-free gravity. basis the percentage of fixed carbon ranges from 90.3 to Toughness. _. 23-51 percent fri­ 46-53 percent frable, able, averages 35 averages 50 per­ 98.6 and averages about 94.2 (tables 5-7). Volatile mat­ percent friable. cent friable. ter on a similar basis ranges in percentage from a maxi­ Agglomeration. Noncoherent residue, Noncoherent residue, nonagglomerating. nonagglomerating. mum of 9.7 in the semianthracite of the western part of Ash______Red, gray, creamy, Red, gray, creamy, the area to a minimum of 1.4 in the anthracite of the white. white. Stain______Will not stain hands. Commonly stains eastern part and averages about 5.8 for both types of hands; black cr coal. dark gray. Ash-softening 2,200°-2,960°C. 2,150°-2,450°C. Ash content on an as-received basis ranges from about temperature. 7.0 to 24.0 percent and averages about 12.2. Sulfur 132 GEOLOGY, SOUTHEKN ANTHRACITE FIELD, PENNSYLVANIA

TABLE 5. Chemical analyses of bed samples from the west-central part of the Southern Anthracite field

[Analyses by U.S. Bureau of Mines]

Percent Dry-mineral- Fusibility of ash (°F) matter-free lasis Proximate Ultimate !» g a B Labo­ O ratory Bedt B '^o a Mine M I 1 or a 2 2 index No. Fixedcar Conditioi Moisture Volatiler Fixedcar Nitrogen Calorific Initialde temper as, Truespe< percent Calorific i 2 1 B I 02 I 0 0 02 £

Dauphin County

LV5 1 1.1 9.6 79.5 9.8 0.7 3.2 82.7 1.1 2.5 13,590 890.3 A1859 2 9.7 80.4 9.9 .7 3.1 83.6 1.1 1.6 13,740 3 10.8 89.2 .8 3.5 92.8 1.2 1.7 15, 260 LV5 1 1.9 8.1 80.3 9.7 .5 3.2 81.5 1.0 4.1 13, 440 2,210 391.8 A7 5152 2 8.3 81.8 9.9 .5 3.0 83.1 1.0 2.5 13,700 3 9.2 90.8 .6 3.4 92.2 1.1 2.7 15, 210 LV5 1 2.1 7.5 80.3 10.1 .5 3.3 80.9 1.0 4.2 13,480 2,430 891.8 A75153 2 7.6 82.1 10.3 .6 3.1 82.6 1.0 2.4 13, 760 3 8.5 91.5 .6 3.5 92.1 1.2 2.6 15, 350 LV5 1 1.1 8.0 80.4 10.5 .6 3.1 82.1 1.0 2.7 13, 560 2,260 892.1 A75154 2 8.1 81.3 10.6 .6 3.0 83.0 1.0 1.8 13, 710 3 9.1 90.0 .7 3.4 92.8 1.1 2.0 15, 340 LV5 1 1.2 8.3 80.2 10.3 .5 3.1 81.8 1.0 3.3 13, 540 2,230 891.7 A75155 2 8.4 81.2 10.4 .5 3.0 82.7 1.1 2.3 13,700 3 9.3 90.7 .6 3.4 92.4 1.2 2.4 15,300 LV5 1 3.6 7.8 81.5 7.1 .6 3.4 82.6 1.0 5.3 13,700 2,180 392.2 A75156 2 8.1 84.5 7.4 .6 3.1 85.6 1.1 2.2 14,200 3 8.8 91.2 .6 3.3 92.4 1.2 2.5 15, 330

LV7 1 1.3 8.2 72.3 18.2 1.3 3.2 72.9 1.2 3.2 12, 130 292.0 A1861 2 8.3 73.3 18.4 1.3 3.1 73.9 1.2 2.1 12, 290 3 10.2 89.8 1.6 3.8 90.5 1.5 2.6 15,060

Lebanon County

'LalrmlaTnina 6(?) 1 2.2 6.6 84.2 7.0 0.7 3.3 85.0 1.0 3.0 14, 130 2,330 393.6 A93499 2 6.8 86.1 7.1 .7 3.2 86.9 1.0 1.1 14,470 3 7.3 92.7 .8 3.4 93.6 1.1 1.1 15,580

Schuylkill County

Eas t Brookside mine __ LV5 1 2.6 8.3 76.2 12.9 0.5 2.9 78.1 0.9 4.7 12,750 2,080 2,160 2,340 1,574 91.5 15,300 A75890 2 8.5 78.2 13.3 .5 2.7 80.2 1.0 2.3 13,100 3 9.9 90.1 .6 3.1 92.5 1.1 2.7 15,100 LV4 1 .9 7.9 83.9 7.3 .5 3.1 85.8 .9 2.4 14,070 2,110 2,190 2,470 1,495 92.1 15,440 A75889 2 7.9 84.7 7.4 .5 3.0 86.5 1.0 1.6 14,200 3 8.6 91.4 .6 3.3 93.4 1.0 1.7 15,330 No. 7 1 4.7 7.1 75.9 12.3 .8 3.4 76.2 1.1 6.2 12,580 2,370 2,660 2,730 1,556 92.9 15,370 A75669 2 7.4 79.7 12.9 .8 3.0 80.0 1.2 2.1 13,200 3 8.5 91.5 .9 3.4 91.8 1.4 2.5 15,150 No. 8 1 4.8 6.4 78.0 10.8 1.0 3.4 77.9 1.0 5.9 12, 910 2,620 2,800 2,910 1,514 93.7 15,500 A75664 2 6.7 82.0 11.3 1.1 3.0 81.8 1.1 1.7 13,570 3 7.6 92.4 1.2 3.4 92.3 1.2 1.9 15,310 No. 8 1 3.6 6.5 79.2 10.7 .9 3.3 79.0 1.2 4.9 13,070 2,750 3 93.7 A75663 2 6.8 82.1 11.1 .9 3.0 82.0 1.2 1.8 13,660 3 7.6 92.4 1.0 3.3 92.2 1.4 2.1 15,250 No. 8M 1 3.6 7.7 74.5 14.2 .6 3.2 75.3 1.2 5.5 12,430 2,710 2,800 2,860 1,483 92.2 15,360 A75682 2 8.0 77.3 14.7 .6 2.9 78.1 1.2 2.5 12,890 3 9.4 90.6 .7 3.4 91.6 1.4 2.9 15. 110 See footnotes at end of table. ECONOMIC GEOLOGY 133

TABLE 5. Chemical analyses of bed samples from the west-central part of the Southern Anthracite field Continued

[Analyses by U.S. Bureau of Mines]

Percent Dry-mineral- Fusibility of ash (°F) matter-free basis Proximate Ultimate Labo­ ratory Bed' deformationInitial Mine (Btu)valueCalorific temperatureFluid specificgravityTrue (Btu)valueCalorific or Volatilematter index temperature temperature No. Condition2 Fixedcarbon carbonFixed Moisture Hydrogen Nitrogen Softening percent Carbon I 3 | O

No. 9 1 4.2 7.2 64.6 24.0 0.6 2.9 G4.9 0.9 6.7 10,640 2,550 2,780 2,920 1,669 92.7 15,260 A75666 2 7.5 67.4 25.1 .6 2.5 67.8 .9 3.1 11, 110 3 10.0 90.0 .8 3.4 90.5 1.2 4.1 14, 820 No. 9 1 3.4 6.6 67.1 22.9 .6 2.9 67.3 .9 5.4 11, 070 2,730 2,870 2,9604 1,640 93.7 '15,430 A75665 2 6.8 69.5 23.7 .6 2.7 G9.7 .9 2.4 11,460 3 8.9 91.1 .8 3.5 91.3 1.2 3.2 15, 020 No. 10 1 5.0 6.9 78.1 10.0 .8 3.4 78.1 1.0 6.7 12, 920 2,350 2,740 2,920 1,48 93.1 15.38C A75667 2 7.3 82.1 10.6 .9 3.0 82.2 1.1 2.2 13,600 3 8.1 91.2 1.0 3.3 91.9 1.2 2.6 15, 210 No. 11 1 6.9 6.4 68.7 18.0 1.3 3.3 68.2 1.0 8.2 11,280 2,360 2,580 2,730 1,63 93.9 15,380 A75668 2 6.9 73.7 19.4 1.4 2.7 73.2 1.0 2.3 12,120 3 8.5 91.5 1.7 3.3 90.8 1.3 2.9 15,030 Phoenix Park No. 3...... No. 14 1 2.8 2.5 82.1 12.7 .5 2.2 79.2 4.6 12, 580 398.6 5956 2 2.5 84.4 13.1 .6 2.0 81.5 2.5 12, 930 3 2.9 97.1 .6 2.3 93.7 .8 2. f 14, 870 Pine Hill rninn No. 6 1 1.6 4.4 83.3 10.7 .5 2.2 81.8 . 7 4.1 13, 130 396.0 A10897 2 4.4 84.7 10.9 .5 2.1 83.1 .7 2.7 13, 340 3 5.0 95.0 .5 2.3 93.2 .8 3.2 14, 960 Pine Knot No. 5 1 5.3 3.8 74.9 16.0 .6 2.5 73.8 .6 6.5 11, 700 2,880 2,980 2, 990-+ 1,710 97.0 15, 140 A75479 2 4.1 79.0 16.9 .6 2.0 77.9 .6 2.0 12,360 3 4.9 95.1 .7 2.4 93.7 .8 2.4 14,860 No. 6 1 4.5 3.9 83.2 8.5 .5 2.5 82.5 1.2 4.9 12, 970 2,940 2,960-f- 1,662 96.5 15,030 A 75488 2 4.1 87.1 8.8 .5 2.0 86.4 1.2 1.1 13, 580 3 4.5 95.5 .6 2.2 94.8 1.3 1.1 14, 890 No. 7 1 5.1 4.6 80.9 9.4 .6 2.5 80.9 .7 5.9 12, 680 2,570 2,780 2,870 1,675 95.7 14,980 A75487 2 4.9 85.2 9.9 .6 2.0 85.2 .8 1.5 13,360 3 5.4 94.6 .7 2.3 94.6 .9 1.5 14,830 No. 7 1 3.5 4.0 77.2 15.3 2.0 2.3 75.7 .6 4.1 12, 030 2,320 2,500 2,670 1,733 97.5 15, 110 A75486 2 4.1 80.1 15.8 2.1 2.0 78.4 .6 1.1 12,460 3 4.9 95.1 2.5 2.3 93.1 .7 1.4 14, 800 No. 8J4 1 4.8 4.3 77.3 13.6 .6 2.5 76.5 .8 6.0 12,900 2,420 2,710 2,810 1,700 96.3 15,040 A75482 2 4.5 81.2 14.3 .6 2.0 80.3 .8 2.0 12, 710 3 5.2 94.8 .7 2.4 93.7 1.0 2.2 14,820 No. 8 1 5.3 4.3 80.9 9.5 .7 2.7 80.1 .8 6.2 12, 750 2,630 2,790 2,860 1,644 96.1 5,130 A75483 2 4.6 85.3 10.1 .8 2.2 846 .8 1.5 13,460 3 5.1 949 .9 2.5 94.0 .9 1.7 14,960 No. 9 1 4.8 4.7 81.6 8.9 .6 2.7 81.0 .8 6.0 12,930 2,340 2,810 2,900 1,625 95.6 15, 130 A75484 2 4.9 85.8 9.3 .6 2.3 85.1 .9 1.8 13, 590 3 5.5 945 .7 2.5 93.8 .9 2.1 14,980 No. 10 1 6.5 4.0 76.9 12.6 .8 2.8 75.4 .7 7.7 12,070 2,790 2,860 2,940 1,658 96.7 15, 140 A75480 2 4.3 82.3 13.4 .9 2.2 80.7 .8 2.0 12,920 3 4.9 95.1 1.0 2.5 93.2 .9 2.4 14,920 No. 10 1 4.6 5.4 77.4 12.6 .5 2.6 77.5 .8 6.0 12,340 2,270 2,360 2,550 1,668 94.8 15, 110 A4481 2 5.7 81.1 13.2 .6 2.2 81.3 .8 1.9 12,940 3 6.5 93.5 .7 2.5 93.7 .9 2.2 14, 920 No. 11 1 6.2 4.9 79.1 9.8 .6 2.8 79.3 .7 6.8 12,540 2,760 2,830 2,910 1,639 95.3 5,090 A75485 2 5.3 84.3 10.4 .7 2.2 84.6 .8 1.3 13, 370 3 5.9 941 .7 2.5 94.5 .9 1.4 14,930 No. 8 1 2. 7 6.5 76.4 14.4 .6 2.3 76.1 1.1 5.5 9 ftSfl 93.7 A28774 2 6.6 78.6 148 .7 2.1 78.3 1.1 3.0 12,410 3 7.8 92.2 .8 2.5 91.9 1.3 3.5 14, 570 1 2.2 6.6 842 7.0 2 6.8 86.1 7.1 3 7.3 92.7 .8 3.4 93.6 1.1 1.1 15,580 93. 6± ...... S W est Brookside mine __ . LV 5 1 3.3 3.3 84.3 9.1 .6 3.1 81.4 .8 5.1 13, 350 97.3d= 5943 2 3.4 87.2 9.4 .6 2.8 84.2 .8 2.2 13, 810 3 3.7 96.3 .6 3.1 92.9 .9 2.4 15,248

i Names and numbers of coal beds are those used in this report and not those s Dry mineral-matter-free fixed carbon percentages calculated by authors used by U.S. Bureau of Mines. 4 U.S. Bureau of Mines analysis compiled from data in tables 3-5 (Turner, *1, sample as received; 2, dried at 105° C; 3, moisture and ash free. 1934). 134 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYUVIANIA

TABLE 6. Chemical analyses of breaker samples from the west-central part of the Southern Anthracite field [Analyses by U.S. Bureau of Mines]

Percent Dry- Calorific mineral- Proximate Ultimate value, matter-free Btu, as basis Saimples analized and collected at Principal source of coal processed in Dry coal breaker on specified date breaker basis (Fixed t ureas Volatile Fixed Ash Sulfur carbon, received matter carbon percent)

Schnylkill County

Blaekwood____ 5.9 8.1 77.4 14.4 0.6 12,240 91.9 7 analyses, Mar. 18, 1948_ Coal beds in Llewellyn For­ mation near village of Llewellyn on Sharp Moun­ tain. Branch______5.0 6.6 79.5 13.9 .6 12,270 93.8 4 analyses, Oct. 7, 1948. Colitz______5.0 5.0 81.8 13.1 .5 12,180 95.6 8 analyses, Sept. 13, 1948... Coal beds in up^er part of Llewellyn Formation near Marlyn in Pottsville quad­ rangle. Joliet______3.7 7.6 82.3 10.1 , 8 13, 030 93. 7 1 analysis of delivered coal Coal beds in Llewellyn For­ in fiscal year 1948. mation near Joliet. D and B_____ 6.0 5.8 78.6 15.6 ,7 11,820 94.8 2 analyses of delivered coal Coal beds in Llewellyn For­ in fiscal year 1952. mation near village of Llewellyn. Kemble______5.1 5.8 81.5 12.7 5 12, 540 94. 7 1 analysis of delivered coal Coal beds in Prttsville For­ in fiscal year 1952. mation abou^ 1^ miles east of Fountain. Marlyn______5.0 5.3 78.1 16.6 .4 11, 790 95.3 8 analyses, Nov. 17, 1949__. Coal beds in Llewellyn For­ mation southeast of Minersville. Penna______5.9 5.6 82.0 12.3 . 7 12, 290 94. 8 2 analyses, June 28, 1949__. Coal beds near Oak Hill mine. Sehrader_____ 4.3 5.2 80.3 14.4 . 6 12, 220 95. 4 7 analyses, Oct. 11, 1948___ Coal beds near Lytle shaft.

Dauphin County

Franklin-Lykens. 2.6 9.2 80.3 10.4 0.5 13,240 90. 7 7 analyses, Jan. 20, 1949 ___ Coal beds on Coal Mountain near Lykens Gap.

RELATION OF FIXED CARBON TO DEFORMATION It also proved that in addition to depth of burial and variations in original composition, some other geologic As early as 1873, Hilt showed that the fixed carbon phenomena must influence the fixed carbon content of content of coal beds increases with depth of burial in the higher rank . some places and concluded that the depth of burial was C. D. White (1915; 1925, p. 269-271; 1935) pro­ the principal reason for coal increasing in rank from pounded and supported his theory of progressive re­ lignite to anthracite. gional carbonization of coal in the eastern United States A detailed study of the coal beds of South Wales and stated that the controlling factor in carbonization (Strahan and Pollard, 1908) showed that the more was horizontal stress or thrust. He demonstrated that deeply buried coal in a single shaft commonly had the chemical variations in lesser rank coals are largely higher fixed carbon content than shallow coal. How­ due to original composition but that in the higher rank ever, when the coal was considered areally, Strahan and coals these original differences "yield to the effects of Pollard found that deposits with the highest fixed car­ dynamochemical transformation and became less con­ bon were located where the overburden apparently had spicuous" (1925, p. 272). White believed that the weight been the least. They concluded that depth of burial was of overburden was responsible for the er.rly stages of a factor in the increase of fixed carbon, but that differ­ fixed carbon increase but that it was of minor impor­ ences in original composition were also important. tance in the more advanced stages. He also believed that Ashley (1918, p. 17) determined that differences in the weight of overburden provided resistance to hori­ amount of fixed carbon in benches of cannel coal versus zontal thrust in the progressive metamor^hism of coal benches of woody bituminous coal or semianthracite at and that the later stages of fixed carbon increase were the same locality gradually disappear as the fixed carbon the result of combining overburden weight, thrust pres­ content approaches 75 percent. This determination sure, and increased temperature resultirg from com­ showed that variations in original composition were pression and friction. White attempted to prove that gradually nullified as the fixed carbon content increases. horizontal thrust was the controlling factor in convert- ECONOMIC GEOLOGY 135

TABLE 7. Average chemical analyses of breaker samples from the west-central part of the Southern Anthracite field [Form of analysis: As received. Analyses by U.S. Bureau of Mines]

Percent Dry mineral - matter-free basis Analyses are averages of samples Proximate Ultimate Calorific identified by following U.S. Principal source of coal processed Breaker value Fixed Calorific Bur. Mines laboratory or index in breaker Mois- Volatile Fixed Ash Sulfur Btu carbon value numbers ture matter carbon percent Btu

Dauphin County

Williamstown__ 3.0 8.7 75.7 12.7 0.7 12,790 91.2 83, 84, 86, 91, 94, 95___ Coal beds north of Williamstown.

Schuylkill County

Buck Run. 5. 0 4. 6 78. 7 11. 5 0.7 12, 430 95. 6 15, 080 1380, 1382 1384-1386, Coal beds near Buck 1389, 1390. Run. Correale__. 5. 9 6. 0 75. 1 12. 9 . 6 12, 140 94. 0 1448-1454______. Coal beds near Donald- son. Di Renzo_. 3. 7 6. 0 78. 7 11. 6 .5 12, 750 94. 2 H10119-H10123. Coal beds close to breaker, which is 2 miles west of Miners ville. K and P. 6. 7 5. 1 77. 4 10. 7 .5 12, 320 94. 9 G67055-G67058. Coal beds near Miners- ville. Legal__ 3. 1 7. 0 76. 5 13. 4 .9 12, 670 93. 2 F66917-F66920. Various coal beds as much as 5 miles from breaker, which is 3 miles north of Goodspring. Lohb__ 4. 5 5. 4 80. 8 9. 3 5 13, 090 94.7 F48297-P48302. Primrose No. 11 coal b^d near Tremont. Lytle__ 3. 8 4. 1 79. 4 12. 8 6 12, 420 96.7 15, 080 1624, 1626, 1627, 1632, Various coal beds in 1637, 1638. Lytle mine. Oak Hill. 3. 6 4. 2 80. 7 11. 6 6 12, 650 96.5 15, 100 1639, 1641, 1645, 1648, Various coal beds in Or.k 1649. Hill mine. Otto____ 6. 9 6. 2 74. 7 12. 1 5 11, 770 93.6 14, 730 1373, 1374, 1376, 1377, Various coal beds in Otto 1379. mine. Penag__ 3. 5 6. 1 79. 4 11. 0 5 12, 980 93.9 F80974-F80981 _ _ __ . Lykens Valley No. 2 coal bed. Sherman. 4. 8 5. 7 76. 6 13. 0 6 12, 350 94.5 1813, 1815, 1816, 1818- 1820, 1822. Swatara_ 7. 9 4. 5 78. 7 8. 8 8 12, 450 95.6 G70356-G70363______Coal beds near Zerbe. Primrose. 5. 3 4. 4 78. 1 12. 2 5 12, 300 96.0 15, 110 1653, 1655, 1657, 1659, 1662, 1665, 1668, 1670. Indian Head. _ 4.6 4.9 76.1 14.3 5 12, 160 95.4 15, 240 1928, 1931, 1935, 1938, Coal beds near Indian 1942, 1945, 1949, 1953. Head breaker, which is between Newton and Tremont. West-West.. 6. 6 5. 9 76. 9 10. 6 12, 150 94. 0 14, 840 1671 and 1673. Coal beds south of Miners ville. New Castle. 7. 4 5. 0 78. 3 9. 3 12, 350 95. 2 1828 and 1829. Coal beds near New Castle, delivered coal, 2 miles east of Pine Knot mine. Westwood.. 2. 9 7. 6 76. 5 12. 0 7 12,920 92. 3 1956, 1958, 1960, 1964, Various coal beds near 1968, 1970. Joliet. ing bituminous coal to anthracite by citing the eastward tween lines of equal volatile matter and structural axes progressive regional carbonization across the Appalach­ "was brought about by thrust pressures applied prior ian basin into the area of this report (192i5, p. 257-258, to and in a different direction from the immediate 265-266). pressures that caused the present anticlines and In 1934, Turner (p. 339-342) strongly endorsed synclines." White's theory of progressive regional carbonization. A year later, Hendricks (1935, fig. 1), in a report on He also presented a map (Turner, fig. 3) on which lines the Arkansas-Oklahoma coal field, showed lines of equal connecting points of equal volatile matter cross the mod­ fixed carbon that trend at a large angle to the known ern anticlinal and synclinal axes at nearly 90° in the structural trends. He attributed this to a regional in­ western part of the Anthracite region. Turner (1934, p. crease in unrelieved thrust pressure, during the str^c- 339-340) stated that this divergence of nearly 90° be­ tural deformation of the coal basin and Ouachita Monn- 136 GEOLOGY, SOUTHERN ANTHRACITE FIELD, PENNSYLVANIA tains to the south, that coincided with the regional in­ as to the timing of this deformation. Heiidricks main­ crease in fixed carbon content. However, in two areas tained that variations in fixed carbon in the Arkansas- where the number of analyses was sufficient to provide Oklahoma coal field were largely due to the forces that detailed control (Heiidricks, 1935, fig. 1 and p. 946), the deformed the Ouachita Mountains whereas Turner be­ maximum fixed carbon content of the coals was found lieved that such variations in the Anthracite region were "to coincide closely with the location of the most tightly caused by forces preceding those that formed the mod­ folded anticline along lines drawn at right angles to the em Appalachians. Ouachita Mountains and extending through these two All available coal analyses of bed, breaker, and tipple areas," Heiidricks' concluded (p. 947), "The major vari­ samples in the area were assembled to determine ations in the fixed carbon content of the coals are di­ whether variations in fixed carbon are due to an early rectly related to structural deformation produced by episode of deformation (Turner's theory), to deforma­ pressure exerted from the south." tion that resulted in the modern structural features Barnes (1962) found that coal in flat-lying unde- (Hendricks' theory), or to depth of burial. Most of formed Tertiary beds in the Cook Inlet area, Alaska, in­ these samples were collected and analyzed by the U.S. creases in rank vertically from subbitimiinous C at the Bureau of Mines, and some are listed in tables 5-7. After surface to high-volatile B bituminous coal at a depth of assembly, the fixed carbon content of each analyzed coal about 11,000 feet. He also found that at the surface sample was calculated according to specifications of the where these beds are deformed structurally, the coal in­ American Society for Testing Materials (1954). The creases in rank from subbituminous to anthracite in a calculated fixed carbon of each sample or group of sam­ distance of about 55 miles in the direction of increasing ples was then plotted on a base map at thQ, correct geo­ structural deformation. graphic position. Finally, a contour map showing lines Heiidricks (1935) and Turner (1934) agreed that de­ of equal fixed carbon content was constructed (fig. 42). formation was the major factor in determining the Normally, only bed or face analyses ar^ used in de­ fixed carbon content of a coal at a specific locality. termining the rank of coal. However, in the Anthracite They arrived at diametrically opposed views, however, region bed analyses are lacking, and present conditions

76°15'

EXP'.ANATION

Isocarbs Contour interval 1 percent

Boundary of Southern Anthracite field

F'.xed carbon Percentage determined from bed sumple analysis

F'xed carbon Percentage determined from breaker and tipple sample analyses

BERKS CO SWATARA HILL

FIGURE 42. Isocarb map of the west-central part of the Southern Anthracite field, Pennsylvania. Samples for bed, breaker, and tipple analyses collected and analyzed by the U.S. Bureau of Mines. ECONOMIC GEOLOGY 137 are not favorable for a program of sample collection tion, the fixed carbon content of beds in the East Brook- and analysis. Because of the lack of proper analyses, it side mine seemingly increases as the overburden de­ was decided to incorporate pertinent data from breaker creases ; but when the analyses are properly located three and tipple analyses in constructing figure 42. This deci­ dimensionally, the fixed carbon content actually in­ sion was made with the full understanding that such creases toward the core of the tightly folded Tremont data are not customarily considered to be satisfactory syncline. In contrast, in the Pine Knot mine, when the for rank determination because the source of the an­ analyses are located correctly, the fixed carbon content alyzed coal generally is not known with sufficient ac­ not only increases as the overburden increases, but also curacy. This possible objection is not pertinent with increases toward the complexly deformed Jugular reference to figure 42 because the source of the coal for thrust fault. Thus, despite the apparent reversal with each breaker and tipple analysis is known with consid­ reference to stratigraphy, the fixed carbon content in erable accuracy. both mines increases toward areas of greater de­ The part of Turner's map (1934, fig. 3) that covers formation. the area was based on 31 bed analyses of coal collected In conclusion, the regional eastward increase of fixed in seven localities. When these analyses are plotted at carbon in the area with greater depth of burial substan­ their correct locations on a map, it is possible to draw tiates Hilt's law. The parallelism of equal fixed carbon lines, as he did, that connect points of equal fixed carbon lines with structural features also substantiates White's, at nearly 90° to the structural axes. However, when the Hendricks', Turner's, and Barnes' conclusion that struc­ breaker and tipple analyses are located properly, it is tural deformation is exceedingly important in de*er- obvious that such connections are not correct. mining the rank of anthracite and semianthracite. Figure 42 shows that lines of equal fixed carbon in AMOUNT OF COAL IN THE REPORT AREA the west-central part of the Southern Anthracite field During the last seven decades, three estimates of ong- regionally parallel the trend of the larger structural inal tonnage of coal preserved in the Anthracite region features and locally parallel the smaller structural fea­ have been made. The earliest of these was by Smith tures. It also shows that the fixed carbon increases east­ (1895, p. 2147-2152). Ashmead (1926, table 20), after ward and toward the cores of the more highly de­ an examination of mine maps, revised Smith's estimate. formed large synclines. The regional eastward increase Subsequently, in 1945, Ashley revised Ashmead's esti­ in fixed carbon is in the direction of the regional plunge mate slightly to include county and culm bank reserves of the major structural features and also in the direction and to show coal produced by river dredges. of greater depth of burial. Turner (1934, fig. 3) and Smith (1895, p. 2150) determined that the SoutHrn White (1925, fig. 1) recognized the eastward increase Anthracite field originally contained 9,198,435,263 gross in fixed carbon, but they did not identify the regional tons, or 10,302,247,474 net tons, of coal in beds more or local parallelism to structural features. The parallel­ than 2.0 feet thick. He used 2,040 net tons of coal per ism between the lines of fixed carbon and structural fea­ acre foot over most of the field, but locally used 2,190 tures shown in figure 42 points inevitably to the fact net tons per acre foot. He did not divide the coal ton­ that the variations in fixed carbon were largely deter­ nage into categories based on coal thickness, amount of mined at the time the structural features were deformed. overburden, and reliability of data. The first step in Secondarily, the regional eastward increase in fixed car­ Smith's method was to determine the probable average bon must have been caused by a greater depth of burial, cumulative thickness of all coal beds along 21 cross which substantiates Hilt's law (1873) and corroborates sections. He then computed the probable average cumu­ the evidence from the South Wales coal field (Strahan lative thickness of coal in the 22 areas that lay between and Pollard, 1908) and the Cook Inlet area, Alaska the cross sections by averaging the probable cumulative (Barnes, 1962). White's (1925, fig. 1), Hendricks' (1935, thickness of coal in the adjacent cross sections. The ton­ p. 947), and Barnes' (1962) conclusion that fixed carbon nage of coal was then determined by multiplying the increases toward areas of greater deformation are vali­ average thickness of coal for each of the 22 areas by dated by the area. Finally, the conclusion reached by the acreage of each of the areas. The combined areas White and Turner (1934, fig. 3) that the lines of equal lying between his cross sections 20 through 29 is approxi­ fixed carbon in the area trend across the structural axes mately the same as the report area. Between and ad­ at nearly right angles is not validated. jacent to his cross sections 20 through 29, he estimated The analyses from East Brookside and the Pine Knot 4,451,176,000 gross tons, or 4,985,317,000 net tons of mines (table 5) seem to contradict one another, in prov­ original coal, which is 48.39 percent of the total origi­ ing that higher rank coal is concentrated in the more nal coal (10,302,247,474 net tons) that he estimated for highly deformed areas. According to stratigraphic posi­ the Southern Anthracite field. 138 GEOLOGY, SOUTHEEN AJSTTHRiACITE FIELD, PENNSTLVIANIA Ashmead in 1926 (table 20) estimated that the origi­ lion tons; Orchard (No. 12) coal bed, 300 nillion tons; nal content of coal in the Southern Anthracite field was Primrose (No. 11) coal bed, 570 million tons; Holmes 10,114,000,000 gross tons, or 11,327,736,000 net tons. He (No. 10) coal bed, 490 million tons; Top Split (No. 9), apparently followed Smith in not calculating reserves Middle Split (No. 8^), and Bottom Split (No. 8) coal in beds less than 2.0 feet thick and by using 2,040 and beds of the Mammoth coal zone, 1.75 billior tons; Skid- 2,190 net tons per acre. Assuming that 48.39 percent more (No. 7) coal bed, 410 million tons; Buck Mountain of the total original coal in the Southern Anthracite (No. 5) coal bed, 470 million tons; Lykens Valley No. 4 field is in the report area as determined from Smith's coal bed, 390 million tons; Lykens Valley No. 5 coal estimate, 5,481,490,000 tons of coal originally underlay bed, 510 million tons; all other coal beds, 1.95 billion the area according to Ashmead's estimate. tons. In 1945, Ashley (table 2) revised Ashmead's estimate The present estimate of the original tonnage of an­ of the original coal in the Southern Anthracite field to thracite which underlay the area is about 2,615 million 10,880,000,000 net tons. Assuming that 48.39 percent tons greater than that of Smith (1895), about 2,118 of the total original coal in the field underlay the area, million tons greater than that calculated by tihe authors the original coal in the area was 5,264,832,000 net tons from Ashmead's 1926 estimate, and about 2,336 million according to Ashley's estimate. tons greater than that calculated by the authors from In this report the original coal content of the area was Ashley's 1945 estimate. calculated as follows: The great discrepancy between the present estimate Using the coal cross sections (Wood and Trexler, and those of Smith, Ashmead, and Ashley is due to the 1968b, sheet 4; 1968c, sheets 5, 6) the underground following: length of each coal bed was measured to 0.04 mile (about 1. The coal beds were found to descend to much greater 200 ft.). The average thickness of coal in each coal bed depths than thought previously, on each cross section was then determined, taking into 2. Much previously unknown thrust fauHng has re­ account the thousands of surface and subsurface meas­ peated coal beds at many places so tl Geol. Soc. SAND AND GRAVEL America, Guidebook for field trips, Pittsburgh Meeting, 3959, Sand has been excavated at several points in the area Field Trip No. 1: p. 1-59. Arndt, H. H., Danilcnik, Walter, and Wood, G. H., Jr., 1963, where weathering has caused the Montebello Sandstone Geology of anthracite in the western part of Shamokin Member of the Mahantango Formation to disintegrate. quadrangle, Northiumiberland County, Pennsylvania: U.S. Principal among these localities are the crests of Fisher Geol. Survey Coal Inv. Map C-47. Kidge and Hooflander Mountain in the Klingerstown Arndt, H. H., and Wood, G. H., Jr., 1960, Late Paleozoic o^og- quadrangle (GQ-700) and the crest of Swope Moun­ eny in eastern Pennsylvania consists of five progressive stages: U.S. Geol. Survey Prof. Paper 400-B, p. B182-B184. tain in the Swatara Hill quadrangle (GQ-689). Arndt, H. H., Wood, G. H., Jr., and Danilcnik, Walter, 1963, Gravel has been quarried from the Sharp Mountain Geology of anthracite in the southern part of the Trevorton Member of the Pottsville Formation on Broad Moun­ quadrangle, Northumberland County, Pennsylvania: U.S. tain north of the villages of Heckscherville and Mount GeoL Survey Coal Inv. Map C-48. Arndt, H. H., Wood, G. H., Jr., and Trexler, J. P., 1962, Sub­ Pleasant (Wood and Trexler, 1968b, pt. 1, sheet 1). division of the Catskill Formation in the western par4: of This gravel was used as base material in highway con­ the Anthracite region of Pennsylvania: U.S. Geol. Survey struction. The conglomerate units of the Sharp Moun­ Prof. Paper 450-C, p. O32-C36. tain are suitable for quarrying at many other places Ashbumer, C. A., and others, 1883-1885, Atlas of Soutt"*rn where they have weathered into gravel. anthracite field, pts. 1-4, 4B, 5, and 6: Pennsylvania GeoL 'Survey, 2d. ROAD METAL Ashley, G. H., 1907, The maximum rate of the deposition, of coal: Econ. Geology, v. 2, p. 34-47. The upper beds of the upper shale member of the 1918, Cannel coal in the United States: U.S. Geol. Surrey BulL 659,127 p. Mahantango Formation and the lower beds of the Trim­ 1923, A geologic time scale: Eng. Mining Jour., v. 115, no. mers Rock Sandstone have been quarried for road metal 25, p. 1106-1109. in numerous shallow pits in the Pine Grove and Swa­ 1945, Anthracite reserves: Pennsylvania Geol. Surrey, tara Hill quadrangles. Some of these pits are large 4th ser., Prog. Rept 130,13 p. and have been excavated extensively during recent Ashmead, D. O., 1926, Anthracite losses and reserves in Pomn- sylvania: Pennsylvania Geol. Survey, 4th ser., Bull. M8, years. As road building continues, these rocks will prob­ 71 p. ably be quarried increasingly for highway construction Averitt, Paul, 1961, Coal reserves of the United States A p^og- materials. ress report, January 1, 1960: U.S. GeoL Survey Bull. 1136, BUILDING STONE 116 p. Barnes, F. F., 1962, Variation in rank of Tertiary coals in the Conglomerate and sandstone of the Tuscarora Sand­ Cook Inlet basin, Alaska: U.S. Geol. Survey Prof. P*Mjer stone, Pocono Formation, and Pottsville Formation 450-O, p. C14-C16. have been widely used in the past for building materials Barren, Joseph, 1907, Origin and significance of tihe MHnch Chunk Shale: Geol. Soc. America Bull., v. 18, p. 449-476. in the Anthracite region. However, because of the ease 1913-14, The Upper Devonian delta of the Appalacl '

316-352 O 69 10 140 GEOLOGY, SOUTHERN" ANTHRACITE HELD, PENNSYLVANIA Behre, O. H., Jr., 1927, Slate in Northampton County, Penn­ Danilchik, Walter, Rothrock, H. E., and Wagner, H. O., 1955, sylvania: Pennsylvania GeoL Survey, 4tih ser., BudL M9, Geology of anthracite in the western part of the Shenan- 308 p. doah quadrangle, Pennsylvania: U.S. GeoL Survey Coal 1933, Slate in Pennsylvania: Pennsylvania Geol. Survey, Inv. Map C-2L 4tih ser., Bull. M16,400 p. Darton, N. H., 1896a, Description of the Piedmont sheet [West BerryhilL, H. L. Jr., and de Witt, Wallace, Jr., 1965, Revised Virginia and Maryland]: U.S. GeoL Survey GeoL Atlas, correlation of Koontz coal and Pennsylvainan-Permian Folio 28. boundary in Georges Creek basin, Allegheny County, Mary­ 1896b, Description of the Franklin quac>angle [West land: Am. Assoc. Petroleum Geologists Bull., v. 39, no. 10, Virginia]: U.S. GeoL Survey GeoL Atlas, FoU^ 32. p. 2087-2090. de Witt, Wallace, Jr., and Colton, G. W., 1959, Revised correla­ BerryhiU, H. L., Jr., and Swanson, V. E., 1962, Revised strati- tions of Lower and Upper Devonian rocks ir western and graphic nomenclature for Upper Pennsylvanian and Lower central New York: Am. Assoc. Petroleum Geologists BulL, Permian rocks, Washington County, Pennsylvania: U.S. v. 43, no. 12, p. 2810-2828. GeoL Survey Prof. Paper 450-O, p. O43-O46. 1964, Bedrock geology of Evitts Creek and Patterson Bode, Hans, 1958, Die floristiische Gliederung des Oberkarbons Creek quadrangles, Maryland, Pennsylvania, and West Vir­ der vereinigten Staaten von Nordamerika: Deutsche GeoL ginia : U.S. Geol. Survey BulL 1173,90 p. OeselL Zeitschr., Jahrg. 1958, v. no, pt. 2, 217-259. Drake, A. A., Jr., Davis, R E., and Alvord, D. C., 1960, Taconic Bowen, Eli, 1848, The coal , being a and post-Taconic folds in eastern Pennsylvania and western general geological, historical, and statistical review of the New Jersey: U.S. GeoL Survey Prof. Paper 400-B, p. B180- anithonacite districts: Pottsville, Pa., E. N. Oarvafflho & Co., B181. 72 p. Dyson, J. L., 1963, Geology and mineral resources of the New Burtner, Roger, Weaver, Richard, and Wise, D. U., 1958, Struc­ Bloomfield quadrangle: Pennsylvania Geol- Survey, 4th ture and stratigraphy of Kittatinny Ridge at Sohuylkill ser., Atlas 137 A, B, 63 p. Gap, Pennsylvania: Pennsylvania Acad. Sd Proc., v. 32, Fenneman, N. M., 1938, Physiography of eastern United States: p. 141-145. New York, McGraw-Hill, 714 p. Ohadwick, G. H., 1933a, Hamilton red beds in eastern New Folk, R L., 1960, Petrography and origin of t^e Tuscarora, York: Science, new ser., v. 77, no. 1986, p. 86-87. Rose Hill, and Keefer Formations, Lower and Middle Siluri­ 1933b, CatskUl as a geologic name: Am. Jour. Sci., 5th ser., an of eastern West Virginia: Jour. Sed. , v. 30, V. 26, no. 155, p. 479-484. no. 1, p. 1-58. 1935a, Summary of Upper Devonian stratigraphy; Am. Frakes, L. A., 1961, Sedimentary structures of the Upper De­ Midland Naturalist, v. 16, no. 6, p. 857-862. vonian of central Pennsylvania: Pennsylvania Acad. Sci. 1935b, Chemung is Portage: GeoL Soc. America BulL, v. Proc., v. 35, p. 116-123. 46, no. 2, p. 343-354. Geiger, H. R, and Keith, Arthur, 1891, The structrre of the Blue Clarke, J. M., 1885, A brief outline of the geological succession Ridge near Harper's Ferry: GeoL Soc. Amer'ra BulL, v. 2, in Ontario Co., New York: New York State Geologist, Ann. no. 1, p. 155-165. Rept 4, p. 9-22. Goddard, E. N., chm., and others, 1948, Rock-color chart: Wash­ Clarke, J. M., and Ruedemann, Rudolph, 1912, The Eurypterida ington, D.C., NatL Research GounciL 6 p. [r>pub. by GeoL of New York: New York State Mus. Mem. 14, 439 p. Soc. America, 1951]. Claypole, E. W., 1885, A preliminary report on the paleontology Goldring, Winifred, 1931, Handbook of paleontology for begin­ of Perry County, describing the order and thickness of its ners and amateurs; pt 2, The formations: N?w York State formations and its folded and faulted structure: Penn­ Mus. Handb. 10,488 p. sylvania GeoL Survey, 2d, Prog. Rept F2, 436 p. Grabau, A. W., 1921, A textbook of geology. Part II, Historical Cleaves, A. B., 1939, The Qriskany Group, m The Devonian of geology: Boston, D. C. Heath & Co., 976 p. Pennsylvania: Pennsylvania GeoL Survey, 4th ser., BuU. Gray, Carlyle, and others, 1960, Geological map of Pennsylvania: G19, p. 92-130. Pennsylvania GeoL Survey, 4th ser., scale 1:250,000. Oloos, Ernst, 1940, Crustal shortening and axial divergence in Gwinn, V. E., 1964, Thin-skinned tectonics in tin Plateau and the Appalachians of southeastern Pennsylvania: Geol. Soc. northwestern Valley and Ridge provinces of the central Ap­ America Bull., v. 51, no. 6, p. 845-872. palachians : Geol. Soc. America BulL, v. 75, p. 863-900. Oolton, G. W., 1961, Geologic summary of the Appalachian Haley, B. R., Arndt, H. H., Rothrock, H. E., and Wagner, H. O., basin, with reference to the suibsuirface disposal of radio­ 1953, Geology of anthracite in the western pr.rt of the Ash­ active waste solutions: U.S. Geol. Survey, TEI-791, 121 p. land quadrangle, Pennsylvania: U.S. GeoL Si\rvey Coal Inv. Conrad, T. A., 1842, Observations on the Silurian and Devonian Map C-13. Systems of the United States, with descriptions of new 1954, Geology of anthracite in the eastern part of the organic remains: Philadelphia Acad. Nat. Sd. Jour., v. 8, Ashland quadrangle, Pennsylvania: U.S. Gecl. Survey Coal pt 2, p. 228-280. Inv. Map O-14. Cooper, G. A., 1930, Stratigraphy of the Hamilton Group of New Hall, James, 1839, Third annual report of the fourth geological York: Am, Jour. Set, 5th ser., v. 19, p. 116-134, 214-236. district of the state of New York: New Yorl- GeoL Survey, Cooper, G. A., ohm., and others, 1942, Correlation of the Devoni­ Ann. Rept 3, p. 238-339. an sedimentary formations of North America: GeoL Soc. Hartnagel, O. A., 1912, Classification of the geoloric formations America BulL, v. 53, no. 12, pt. 1, p. 1729-1798. of the state of New York: New York State Mus. Handb. 19, Danilchik, Walter, Arndt, H. H., and Wood, G. H., Jr., 1962, 2d ed., 99 p. Geology of anthracite in the eastern part of the Shamokin Hendricks, T. A., 1935, Carbon ratios in part of the Arkansas- quadrangle, Northumberland County, Pennsylvania: U.S. Oklahoma coal field: Am. Assoc. Petroleum Glogists BulL, GeoL Survey Coal Inv. Map C-46. V. 19, no. 7, p. 937-047. REFERENCES 141

Hilt, Carl, 1873, Die Bezsiehungen zwisehen der Zusammenset- 1960: WasMngton, U.S. Govt Printing Office, v. 2, p. 149- zung und den technischen Eigensehaften der SteinkoMe: 203. Ver. deutscher Ingenieare. Zeitschr., v. 17, no. 2, p. 194-202. Nevin, C. M., 1936, Principles of structural geology: 2d ed., New Hoskins, D. M., 1961, Stratigraphy and paleontology of the York, John Wiley & Sons, 248 p. of Pennsylvania and adjacent Parker, J. M., 1942, Regional systematic jointing in slighitir de­ states: Pennsylvania Geol. Survey, 4th ser., Bull. G36, formed sedimentary rocks: Geol. Soc. America BulL, v. 53, 124 p. no. 3, p. 381-408. Hoskins, D. M., and Conlin, R. R., 1958, Invertebrate fossils from Pelletier, B. R., 1958, Pocono paleocurrents in Pennsylvania and the Bloomsburg Formation of central Pennsylvania: Penn­ Maryland: GeoL Soc. America BulL, v. 69, no. 8, p. I'M®- sylvania Acad. Sci. Proc., v. 32, p. 156-161. 1063. Hudson Coal Company, 1932, The story of anthracite: New Pennsylvania Bureau of Statistics and Information, 1944, Penn­ York, Hudson Coal Co., 425 p. sylvania's mineral heritage: Harrisburg, Pa., Dept. Internal Joesting, H. R., Keller, Fred, Jr., and King, Elizabeth, 1949, Affairs, 248 p. Geologic implications of aeromagnetic survey of Clearfield- Pennsylvania Geological Survey, 1954, Guidebook, 20th annual Philipsburg area, Pennsylvania: Am. Assoc. Petroleum field conference of Pennsylvania geologists, Hershey, May Geologists Bull., v. 33, no. 10, p. 1747-1766. 28-30,1954: Harrisburg, Pa., 44 p. Kehn, T. M., and Wagner, H. C., 1955, Geology of anthracite in Perry, W. J., Jr., 1964, Geology of the Ray Sponaugle well, the eastern part of the Shenandoah quadrangle, Pennsyl­ Pendleton County, West Virginia: Am. Assoc. Petroleum vania : U.S. Geol. Survey Coal Inv. Map C-19. Geologists Bull., v. 48, no. 5, p. 637-669. Kindle, E. M., and Taylor, F. B., 1913, Description of the Niagara Platt, Franklin, and Platt, W. G., 1877, Report of progress in quadrangle [New York]: U.S. Geol. Survey Geol. Atlas, the Cambria and Somerset district of the bituminous coal Folio 190, 25 p. fields of western Pennsylvania; Part I, Cambria: Pennsyl­ Klemic, Harry, Warman, J. C., and Taylor, A. R., 1963, Geology vania Geol. Survey, 2d, Rept. HH, 194 p. and uranium occurrences of the northern half of the Lehigh- Prime, Frederick, D'lnvilliers, E. V., Sanders, R. H., and others, ton quadrangle, Pennsylvania, and adjoining areas: U.S. 1884, Geologic map of Berks County: Pennsylvania OeoL Geol. Survey BulL 1138,97 p. Survey, 2d. Lesley, J. P., 1876, The Boyd's Hill gas well at Pittsburgh, Read, C. B., 1947, Pennsylvanian floral zones and floral prov­ Pennsylvania: Pennsylvania Geol. Survey, 2d, Rept. L, app. inces: Jour. Geology, v. 55, no. 3, pt. 2, p. 271-279. E, p. 217-237. 1955, Floras of the Pocono Formation and Price Sand­ Lesley, J. P., D'lnvilliers, E. V., and others, 1892-95, A sum­ stone in parts of Pennsylvania, Maryland, West Virginia, mary description of the geology of Pennsylvania: Pennsyl­ and Virginia: U.S. Geol. Survey Prof. Paper 263, 32 p. vania Geol. Survey, 2d, Final Rept., 3 v., 2588 p. Read, C. B., and Mamay, S. H., 1960, Upper Paleozoic floral roues Lesquereux, Leo, 1880-84, Description of the coal flora of the of the United States: U.S. Geol. Survey Prof. Paper 400-B, formation in Pennsylvania and throughout p. B381-B383. the United States: Pennsylvania Geol. Survey, 2d, Rept. P, Reeside, J. B., Jr., 1917, The Helderberg Limestone of central 3 v., 977 p.; atlas (1879). Pennsylvania: U.S. GeoL Survey Prof. Paper 108-F, p. Lohman, S. W., 1937, Ground water in northeastern Pennsyl­ 185-225. vania: Pennsylvania Geol. Survey, 4th ser., Bull. W4, Rodgers, John, 1963, Mechanics of Appalachian foreland fold­ 312 p. ing in Pennsylvania and West Virginia: Am. Assoc. Petro­ Mclver, N. L., 1960, Upper Devonian paleocurrents in the central leum Geologists Bull, v. 47, no. 8, p. 1527-1536. Appalachian Mountains [abs.]: Geol. Soc. America Bull., Rogers, A. E., and Kerr, P. F., 1933, Thin section mineralogy: v. 71, no. 12, pt 2, p. 1926. New York, McGraw-Hill, 311 p. McKee, E. D., and Weir, G. W., 1953, Terminology for strati­ Rogers, H. D., 1843, An inquiry into the origin of the Appalachian fication and cross-stratification in sedimentary rocks: Geol. coal strata, bituminous and anthracitic: Assoc. Am. Geolo­ Soc. America Bull., v. 64, no. 4, p. 381-389. gists and Naturalists, Reports of the first, second, and Mather, W. W., 1840, Fourth annual report of the first geological third meetings, 1840-42, Rept. 71, p. 433-474. district of the state of New York: New York Geol. Survey 1858a, Geological and topographical map of the anthra­ Ann. Rept 4, p.. 209-258. cite fields of Pennsylvania: Pennsylvania Geol. Survey, 1st. Maxwell, J. A., and Rothrock, H. E., 1955, Geology of anthracite 1858b, The geology of Pennsylvania, a government sur­ in the western part of the Delano quadrangle, Pennsylvania: vey : Pennsylvania Geol. Survey, 1st, 2 v.: 586 p., lO'.tfl p. U.S. Geol. Survey Coal Inv. Map C-25. Rothrock, H. E., Wagner, H. C., and Haley, B. R., 1950, Geology Miller, B. L., 1926, Taconic folding in Pennsylvania: Geol. Soc. of anthracite in the west-central part of the Mount Carmel America Bull., v. 37, no. 3, p. 497-511. quadrangle, Pennsylvania: U.S. Geol. Survey Coal Inv. Map Miller, J. T., 1961, Geology and mineral resources of the Loysville C-3. quadrangle, Pennsylvania: Pennsylvania Geol. Survey, 4th Rothrock, H. E., Wagner, H. C., Haley, B. R., and Arndt, H- EL, ser., GeoL Atlas 127,47 p. 1951a, Geology of anthracite in the southwestern part of Miller, J. T., and Conlin, R. R., 1959, Upper Devonian rock-strati- the Mount Carmel quadrangle, Pennsylvania: U.S. GeoL graphic nomenclature in Pennsylvania [afos.]: Geol. Soc. Survey Coal Inv. Map O-7. America BulL, v. 70, no. 12, pt. 2, p. 1645-16. 1951b, Geology of anthracite in the east-central part of Moore, R. C., chm., and others, 1944, Correlation of Pennsyl- the Mount Carmel quadrangle, Pennsylvania: U.S. GeoL vanian formations of North America: GeoL Soc. America Survey Coal Inv. Map O-10. Bull., v. 55, no. 6, p. 657-706. 1953, Geology of anthracite in the southeastern part o* the Moyer, F. T., Vaughan, J. A., and Oooke, M. I., 1961, Coal Penn­ Mount Carmel quadrangle, Pennsylvania: U.S. GeoL Survey sylvania anthracite, in U.S. Bur. Mines, Minerals Yearbook, Coal Inv. Map C-12. 142 GEOLOGY, SOUTHEEN ANTHRACITE FIELD, PENNSYLVANIA Sanders, B. H., 1881, Geological map of Dauphin County: Penn­ and prospects of the Stony Creek Coal Estat^ . . .: Phila­ sylvania GeoL Survey, 2d. delphia, E. G. Dorsey, 113,74 p. Schuchert. Oharles. 1916. Silurian formations of southeastern Taylor, R. C., 1841, Notice of a model of the western portion of New York, New Jersey, and Pennsylvania: Geol. Soc. Amer­ the Schuylkill or Southern coal-field of Pennrvivania: Am. ica Bull., v. 27, no. 3, p. 531-554. Jour. Sci., v. 41, no. 1, p. 80-91. Sheppard, R. A., 1956, A systematic joint study in the folded Trexler, J. P., 1964, The geology of the Klinger^town, Valley Appalachians: Pennsylvania Acad. Sci. Proc., v. 30, p. 142- View, and Lykens quadrangles, Southern Anthracite field, 145. Pennsylvania: U.S. GeoL Survey open-file rept, 519 p., 55 Smith, A. DW, 1891, Geological map of Schuykill County: Penn­ figs. sylvania Geol. Survey, 2d. Trexler, J. P., and Wood, G. H., Jr., 1968a, Geologic map of 1895, Report on the Anthracite region, in Lesley, Klingerstown quadrangle, Dauphin, Northumberland, and J. P., and others, A summary description of the geology of Schuylkill Counties, Pennsylvania: U.S. Geol. Survey Geol. Pennsylvania: Pennsylvania Geol. Survey, 2d., Final rept., Quad. Map GQ-700. v. 3, pt. 1, p. 1916-2152. 1968b, Geologic map of Lykens quadrangle, Dauphin, Stevenson, J. J., 1893, Origin of the Pennsylvania anthracite: Lebanon, and Schuylkill Counties, Pennsylvania: U.S. Geol. Geol. Soc. America Bull., v. 5, p. 39-70. Survey GeoL Quad. Map GQ-701. 1904, Carboniferous of the Appalachian basin: Geol. Soc. 1968c, Geologic map of Valley View quadrangle, North­ America Bull., v. 15, p. 37-210. umberland and Schuylkill Counties, Penns7lvania: U.S. 1906, Carboniferous of the Appalachian basin: Geol. Soc. Geol. Survey GeoL Quad. Map GQ-699. America Bull., v. 17, p. 65-278. Trexler, J. P., Wood, G. H., Jr., and Arndt, H. H., 1961, Angular Stose, G. W., 1909, Description of the Mercersburg-Ghambers- unconformity separates Catskill and Pocono Formations in burg district [Pennsylvania]: U.S. Geol. Survey Geol. Atlas, western part of Anthracite region, Pennsylvaria: U.S. GeoL Folio 170. Survey Prof. Paper 424-B, p. B84-B88. 1930, Unconformity at the base of the Silurian in south­ 1962, Uppermost Devonian and Lower Mississippian rocks eastern Pennsylvania: Geol. Soc. America Bull., v. 41, no. 4, of the western part of the Anthracite region of eastern p. 629-657. Pennsylvania: U.S. Geol. Survey Prof. Paper 450-C, Strahan, Aubrey, and PoUard, William, 1908, The coals of South p. C36-O39. Wales, with special reference to the origin and distribution Tryon, F. G., and Mann, L., 1928, Coal in 1925, in U.S. Bur. of anthracite: Great Britain Geol. Survey Mem., 78 p. Mines, Mineral resources of the United States 1925: Wash­ Strong, H. K., chm., and others, 1839, Report to the legislature of ington, U.S. Govt. Printing Office, p. 393-533. Pennsylvania, containing a description of the Swatara min­ Turner, H. G., 1934, and semianthracites of Penn­ ing district: Harrisburg, Pa., Boas & Ooplan, 61 p. sylvania: Am. Inst. Mining and Metall. Engineers Trans., Swartz, C. K., 1913, Correlation of the Lower Devonian: Mary­ v. 108, p. 330-343. land Geol. Survey, Lower Devonian, p. 96-132. Twenhofel, W. H., chm., and others, 1954, Correlation of the Swartz, C. K., and Swartz, F. M., 1930, Age of the Shawangunk Ordovician formations of North America: Geol. Soc. Amer­ Conglomerate of eastern New York: Am, Jour. Sci. 5th ser., ica Bull., v. 65, no. 3, p. 247-298. v. 20, p. 467-^74. Uhler, P. R., 1905, The Niagara period and its associates near 1931, Early Silurian formations of southeastern Pennsyl­ Cumberland, Maryland: Maryland Acad. Sci, Trans., new vania : Geol. Soc. America Bull., v. 42, no. 3, p. 521-661. ser., v. 2, p. 19-26. 1941, Early Devonian and Late Silurian formations of Ulrich, E. O., 1911, Revision of the Paleozoic systens: Geol. Soc. southeastern Pennsylvania: GeoL Soc. America Bull., v. 52, America Bull., v. 22, p. 281-680. no. 8, p. 1129-1191. U.S. Atomic Energy Commission, 1962, Civilian nu?lear power Swartz, C. K., chm., and others, 1942, Correlation of the Silurian a report to the President 1962: Washington, 67 p. formations of North America: Geol. Soc. America Bull., U.S. Bureau of Mines, 1928-32, Mineral resources of the United v. 53, p. 533-538. States, 1924-1931: Washington, U.S. Govt. F-inting Office Swartz, F. M., 1932, Revision of the ostracode family Thlip- (annual publication; continued by U.S. Bur, Mines, Min­ suridiae, with description of new species from the Lower erals Yearbook, 1932 to date). Devonian of Pennsylvania: Jour. Paleontology, v. 6, no. 1, 1933 to date, Minerals Yearbook [1932]: Washington, p. 36^58. U.S. Govt. Printing Office (annual publication). 1939, The Keyser Limestone and Helderberg group, in The U.S. Geological Survey, 1883-1927, Mineral resources of the Devonian of Pennsylvania: Pennsylvania Geol. Survey, 4th United States, 1882-1923: Washington, U.S. Govt. Printing ser., Bull. G19, p. 29-91. Office (annual publication; continued by U.S. Bur. Mines to 1946, Faunal development, conditions of deposition, and 1931, then by U.S. Bur. Mines, Minerals Yearbook, 1932 to paleogeography of some Appalachian mid-Paleozoic sedi­ date). ments: Oong. Panamericano Ingeniaria Minas e Geologia, Vanuxem, Lardner, 1839, Third annual report of the geological 2d, Rio de Janeiro, 1946, Oomm. Geologia, Paleontologia, survey of the third district: New York Geol. Survey Ann. Mineralogia e Petrologia, Anais, v. 3, no. 2a, p. 9-33. Rept. 3, p. 241-285. 1948, Late Ordovician and Silurian facies, conditions of 1840, Fourth annual report of the geological survey of the deposition and paleogeography in north-central Appalach­ third district: New York Geol. Survey Ann. Rept 4, ians [abs.] : Aim. Assoc. Petroleum Geologists Bull., v. 32, p. 355-383. no. 11, p. 2160. -1842, Geology of New York. Part III, comprising the Taylor, R. C., 1840, Two reports: on the coal lands, mines, and survey of the third geological district: Albany, 306 p. improvements of the Dauphin and Susquehanna Coal Com­ Ver Wiebe, W. A., 1936, Geosynclinal boundary faults: Am. pany and of the geological examinations, present condition Assoe. Petroleum Geologists Bull., v. 20, no. 7, p. 910-938. REFERENCES 143

Wagner, H. O., 1953, Constitution diagrams of Pennsylvania Williams, H. S., 1887, On the fossil faunas of the Upper Devoni­ anthracite: U.S. GeoL Survey Bull. 995-A, 18 p. an ; the Genesee section, New York: U.S. GeoL Survey PulL Weller, J. M., chm., and others, 1948, Correlation of the Missis- 41,123 p. sippian formations of North America: Geol. Soc. America Willis, Bailey, 1893, The mechanics of Appalachian struolr^re: Bull., v. 59, p. 91-196. U.S. GeoL Survey Ann. Bept. 13, pt 2, p. 211-281. White, C. D., 1900, The stratigraphic succession of the fossil 1912, Index to the stratigraphy of North America: U.S. floras of the Pottsville formation in the Southern Anthracite Geol. Survey Prof. Paper 71,894 p. field, Pennsylvania: U.S. Geol. Survey Arm. Rept. 20, pt. Wilmarth, M. G., 1938, Lexicon of geologic names of the Urited 2 (1898-99), p. 749-953. States: U.S. GeoL Survey Bull. 896,2 v., 2396 p. 1904, Deposition of the Appalachian Pottsville: Geol. Soc. Wood, G. H., Jr., 1968, Geologic map of Tower City quadrangle, America Bull., v. 15, p. 267-282. Dauphin, Lebanon, and Schuylkill Counties, Pennsylvania: 1915, Some relations in origin between coal and petro­ U.S. Geol. Survey Geol. Quad. Map GQ-698. leum: Washington Acad. Sci. Jour., v. 5, no. 6, p. 189-212. Wood, G. H., Jr., and Kehn, T. M., 1961, Sweet Arrow fault, east- central Pennsylvania: Am. Assoc. Petroleum Geolo'dsts 1925, Progressive regional carbonization of coals: Am. Inst. Mining and Metall. Engineers Trans., v. 71, p. 253-281. Bull., v. 45, no. 2, p. 256-263. 1968a, Geologic map of Swatara Hill quadrangle, F^rks 1934, The age of the Pocono: Am. Jour. Sci., 5th ser., and Schuylkill Counties, Pennsylvania: U.S. GeoL Survey v. 27, no. 160, p. 265-272. Geol. Quad. Map GQ-689. 1935, Metamorphism of organic sediments and derived 1968b, Geologic map of Pine Grove quadrangle, B?rks, oils: Am. Assoc. Petroleum Geologists Bull., v. 19, no. 5, p. Lebanon, and Schuylkill Counties, Pennsylvania: U.S. Geol. 589-617. Survey Geol. Quad. Map GQ-691. White, I. C., 1881, The geology of Susquehanna County and Wood, G. H., Jr., and Trexler, J. P., 1968a, Geologic map of Wayne County: Pennsylvania Geol. Survey, 2d, Kept. G5, Tremont quadrangle, Northumberland and Schuylkill Coun­ 243 p. ties, Pennsylvania: U.S. GeoL Survey GeoL Quad. Map 1882, The geology of Pike and Monroe Counties: Penn­ GQ-692. sylvania Geol. Survey, 2d, Kept. G6,334 p. 1968b, Geologic maps of anthracite-bearing rocks in the 1883, The geology of the Susquehanna River region in west-central part of the Southern Anthracite field, Pennsyl­ the six counties of Wyoming, Lackawanna, Luzerne, vania : eastern area: U.S. GeoL Survey Misc. Geol. Inv. Map Columbia, Montour, and Northumberland: Pennsylvania 1-528. Geol. Survey, 2d, Kept. G7,464 p. 1968c, Geologic maps of anthracite-bearing rocks in the Willard, Bradford, 1933, "CatsMll" sedimentation in Pennsyl­ west-central part of the Southern Anthracite field, Pennsyl­ vania : GeoL Soc. America Bull., v. 44, no. 3, p. 495-516. vania: western area: U.S. GeoL Survey Misc. GeoL Inv. 1934, Early Chemung shore line in Pennsylvania: GeoL Map 1-529. Soc. America Bull., v. 45, no. 5, p. 897-908. Wood, G. H., Jr., Trexler, J. P., and Arndt, H. H., 1962. Pennsyl- 1935a, Hamilton Group in central Pennsylvania: GeoL vanian rocks of the southern part of the Anthracite rcsgion Soc. America Bull., v. 46, no. 2, pp. 195-224. of eastern Pennsylvania: U.S. Geol. Survey Prof. Paper 1935b, Middle-Upper Devonian contact in Pennsylvania: 450-C, p. C39-C42. Pennsylvania Acad. Sci. Proc., v. 9, p. 39-44. Wood, G. H., Jr., Trexler, J. P., Arndt, H. H., Telenosky, Andy, 1935c, Portage Group in Pennsylvania [abs.]: Geol. Soc. and Soren, Julian, 1956, Subdivision of the Pottsville forma­ America Proa, 1934, p. 123. tion in Southern Anthracite field, Pennsylvania: Am. A ssoc. 1935d, Portage Group in Pennsylvania: GeoL Soc. Amer­ Petroleum Geologists Bull., v. 40, no. 11, p. 2669-2688. ica Bull., v. 46, no. 8, p. 1195-1218. Wood, G. H., Jr., Trexler, J. P., Soren, Julian, and Telennsky, 1936, Continental Upper Devonian of northeastern Andy, 1962, Geology of rocks of Pennsylvanian age in the Pennsylvania: Geol. Soc. America Bull., v. 47, no. 4, pp. 565- southern half of the Tremont quadrangle, Schuylkill Connty, 607. Pennsylvania: U.S. Geol. Survey Bull. 1112, p. 181-2(K 1939a, Middle and Upper Devonian, in The Devonian of Wood, G. H., Jr., Trexler, J. P., and Telenosky, Andy, 1968, Pennsylvania: Pennsylvania Geol. Survey, 4th ser., Bull. Geologic map of Minersville quadrangle, Schuylkill County, C19, p. 131-445. Pennsylvania: U.S. GeoL Survey GeoL Quad. Map G<;-690. 1939b, Guide to the geology of the upper Schuylkill Val­ Wood, G. H., Jr., Trexler, J. P., Telenosky, Andy, and Soopen, ley: Pennsylvania Geol. Survey, 4th ser., Bull. G14, 23 p. Julian, 1958, Geology of the northern half of the Miners­ ville quadrangle and a part of the northern half of the 1941, The Harrisburg axis: Pennsylvania Acad. ScL Proc., v. 15, p. 97-102. Tremont quadrangle, Schuylkill County, Pennsylvania: U.S. Geol. Survey Coal Inv. Map C-43. 1943, Ordovician clastic sedimentary rocks in Pennsyl­ Woodward, H. P., 1964, Central Appalachian tectonics an*T the vania : Geol. Soc. America Bull., v. 54, no. 8, p. 1067-1121. deep basin: Am. Assoc. Petroleum Geologists Bull., v. 48, Willard, Bradford, and Cleaves, A. B., 1933, Hamilton Group no. 3, p. 338-356. in eastern Pennsylvania: GeoL Soc. America Bull., v. 44, Teakel, L. S., 1958, Early Silurian and Late Ordovician paleo- no. 4, p. 757-782. currents in the central Appalachians [abs.]: GeoL Soc. 1938, A Paleozoic section in south-central Pennsylvania: America Bull., v. 69, no. 12, pt. 2, p. 1667-1668. Pennsylvania Geol. Survey, 4th ser., Bull. G8, 33 p. 1962, Tuscarora, Juniata, and Bald Eagle paleocurrents 1939, Ordovician-SUurian relations in Pennsylvania: and paleogeography in the central Appalachians: GeoL Soc. GeoL Soc. America Bull., v. 50, no. 7, p. 1165-1198. America Bull., v. 73, no. 12, p. 1515-1539.

INDEX

[Italic page numbers indicate major references]

Page Catskill Formation Continued Page Big Lick Mountain anticline...... 86, 87,89,106,114 Spechty Kopf Member.... 18, 41,51,52, 53,55,84 Acadia..____.....__._...... 51,53,56 Big Lick Mountain fault complex__.--.-._ 108 coal beds..______121 Acadian anticlines_..___.. ______._ 84 Big Lick Mountain tunnel...____.-..__. 97 thickness______..___ 57 Acadian orogeny.______.... 17, Big Lick prospect-______.____ 132 Walcksville Sandstone Member. _____ 45 48,51,52, 55,57, 58,60,63,116 BiUy Best coal bed.- 127 Cayuga Series, Mich., Ohio, and N.Y..___ 15 structural features formed during_------8, 84 Black Mine coal bed.--.._ ...... 129,130 Center iron sandstone.. ______12 Acadian syncllnes.______.______84 Blackheath coal bed.._....._...... _ 127,128 Chemical analyses, average, breaker sample.. 134, Acknowledgments_.______._ 7 Blackwood fault.------___...... _.... 87,89, 135 Albion Group, N.Y..___-----____.______.__. 11 90,92,102,103, 104, 105,108,109,114,117 Chemicalanalyses, coal-bed samples_.____ 132 Albion Sandstone.-...__..__.-.-.--_._ 11 Blackwood mine...... _...... __..__... 128 Chemung Formation______41, 45 Allegheny Formation______. ___ 79,82,131 Bloomsburg delta...__.___.______16 Cherry Ridge Member of Catskill Formation. 18, Lower Kittanniag coal bed____..-...- 78 Bloomsburg Red Beds...... 18,13,15,104: 41,^,58 Allegheny Plateau______.______.._ 113 depositional environment-.._------15 depositional environment... __.. ____ 53 Ailing, H. L., cited- ...... 15,16 minerals______._____- 14 isopach map_..._ . . ___ 58 Alluvium______. _ 8& thickness____.______.______13 minerals_____..__..___..__.. 53 Alsen Limestone, N.Y..___.______22 Bloyd Shale...... 78 pebbles in conglomerate..-..____..... 53 Altitude of area.__...._____--_____. 4 Blue Mountain...... 8,9,10, IS, 82,84,89,108 thickness__..__..__------_..... 5% Analomink Red Shale..______45 Bluefield Shale, W. Va__. 70 Church coal bed-...-_.. .-.-. .__ 128 Anticlines, Acadian..__.___._____..... 84 .._____._ _... 70 Clarke, J. M., cited..__. 11 description. .______87 Bode, Hans, cited...______... 78 Clarks Ferry Member of CatskUl Formation.. 51 Appalachian Mountain system....__..__... 113 plant identifications by...... _-____ 83 Claypole, E. W., cited 32 Appalachian orogeny ______. ______. 8, Bossardville Limestone, Pa., N.J., and N.Y.. 16 Cleavage. ...._....._...._...... US 17, 48, 52, 58, 70, 71, 73, 74, 78, 81, 84, 85, Bottom Split (4B) bench..-...... -.---.----- 126 Cleaves, A. B., cited-______.____ 7,24,26 112, 114, 116. Bottom Split (No. 8) coalbed-. -- 128 Applebee fault______.._.. 93,108 Bowen, Eli, cited.-_____._____._.. 6 Clinch Sandstone, southern Appalachians__ 11 Arkansas-Oklahoma coal field. _.______. 136 Boyd's Hill well ...... - 70 Clinton Formation...... __...... 10,11,108 Arndt, H. H., cited.. ... 42,53,55,59,62,65,113 Brallier Shale,...... 37,38,41 depositional environment--...- __... IS Ashley, G. H., cited..-...... 37,81,134,137,138 Branchdale anticline... _. ______85,87,88,106 fossils.... 13 Ashmead, D. C., cited . 137,138 Briggs, L. L, cited..___-______15,16 minerals__-- .- - -._____... IS Atlantic Coastal Plain fall line___...... 64,78 Broad Mountain...... _.... 55,58,59,62, thickness.-----.______1 2 Auburn promontory._ __.- ___ 16, 71, 73,74, 77,82,84,97,99,101,103,117,122 Cloos, Ernst, cited-.-.-_...... ___.. 64,78 17,23,25,26,27,29,34,36,116 Broad Mountain anticlinorium. ______. 37, Coal,.... _ ._ 117 Averitt, Paul, cited___...___...._____ 121 42,53, 58,84, 85, 88,94,96,98,108,114,117 amount in report area. ...-. .. 137 ancestral....______.______116 characteristics______.______131 Brookside mine..______92,97,188,184,128 chemical composition__. ______131 Baird Run...... 103 Buck Run mine______.___ _... 127 physical properties.______... 131 Barclaugh coal bed.-..-.___.__..__ 127,128 Buddys Run Member of Catskill Formation.. 18, production. ..___..___..__ 119 Barnes, F. F., cited.__..__._.___.. 136,137 37,^,51,53,54,55 reserves of anthracite___....__.._ 3,7,137 BarreU, Joseph, cited ._..__. . 6,47,68 correlation..______55 Coal beds: Bass Island Dolomite, Mich., and Ohio....__ 16 depositional environment-..-- - 55 average thickness and range, Llewelyn Bear Creek ______5 isopath map.. __..-.___ _ 54 Formation...______1%S Bear Mountain_____...... ___. 71, 73,74,82,97 minerals.______. 54 PottsviUe Formation...... 122 Beckville Member of Pocono Formation_ 56,59,84 pebbles in conglomerate..______. 54 Beckville Member of Pocono Formation.. 121 coal beds______121 thickness______54 chemical analyses of bed samples____ 1SS isopach map_ ___.. ______. 59 Building stone..__.___..__.. _ 139 description._ ____..______.. 1S1 minerals...______61 Burket Black Shale Member of Harrell Shale. 37, 38 LleweUyn Formation_____. __ 121,1£%,1S6 pebbles and cobbles in conglomerate___ 60,61 Bottom Split (No. 8) ... 80, thickness______69 86,87,89,90,^7,^38 Buck Mountain (No. 5).______75, Beckville Member of Pocono Formation and Canadaway Group....__ _ 51 Spechty Kopf and Cherry Ridge 77,79,80,82,86,91, 1S5, !»* 138 Members of Catskill Formation, Cape Cumberland..______. 34 Clinton (No. 15J£)__. ... 81,126 unconformity between... 59 Carbon-ratio theory, advanced by C. D. description.- ...... ___. 126 Becraft Limestone, N.Y______.____... 22 White._...... 6 Diamond, (No. 14)... 79,80,126,129, 13P, 138 Berry Mountain ...... 5,56,58,59,62,65,84,85 Catsfcill-Chemung Group_..__ . 41 Diamond Leader (14L)______80,126 Berry Mountain anticline__..___.... 58,86,107 CatskUl Formation...... _.. 6,7,18,37,^,112 Faust (No. 21)___...._...__.. 83.126 Beuchler fault___.______51, Buddys Run Member______18, 37,^,51,53 Holmes (No. 10) __- 80,89,90,126,12P. 138 52, 55, 58, 59, 103, 104, 105, 108, 109, 114, Cherry Ridge Member.______18,41,51,58 Little Clinton (No. 15^) ______80,126 117. Clarks Ferry Member.______51 Little Diamond (No. 15) ___.__ 80,126 Beurysyncline. .____.___ 86,97,102,103 Damascus Member______18,37, 41,46, 104 Little Orchard (No. 13)_____ 80,126, ISO Big Dirt coal bed ._...... 128 Honesdale Sandstone Member...... 18,41,48 Little Tracy (No. 17)...... 80,126, ISO, 131 Big Lick mine...... __...... 122,124,126,127 Irish Valley Member ______. 18, Lower Four Foot (No. 9J_)_____ 80-126 Big Lick Mountain-__._. 5,71,73,74,82,91,97,98 37,38, 40,41,42, 88,92,104,105 Lykens Valley Nos. l-4_ ...... 8f, JSf 145 146 INDEX

Coal beds Continued Coal mines Continued Page Llewellyn Formation Continued Page Sharp Mountain Member of Pottsville East Franklin mine______129 Middle Split (No. fyQ~ ~ 86, Formation, Qoodspring mine_.. 125 East George Head anticline______56,87,107 87,89,107,126,127,128 Penag mine_. ______125 Eastern Middle Anthracite field______67 Orchard (No. 12)...... 80,92,126, 189,138 Pine Knot mine______125 Economic Geology__..______117 Peach Mountain (No. 18)__.___ 79, Tumbling Run Member of Pottsville 80,87,89,126,129, ISO, 138 Formation, Brookside mine__ 722,124 Eden Group______9 Primrose (No. 11)____...... ___ 80, Big Lick mine...... __ 122,124 Eisenhuth Run anticline______86,97,102,103 89,90,126,128,129,138 Kalmia mine______122 Elk Mountain Sandstone______5 7 Rabbit Hole (No. 20)_.__...... 80,126 Porter mine.__...... 122,124 Seven Foot (No. 6).._...... 80,86,126,127 Short Mountain mine______122,124 F Skidmore (No. 7)______80, Tower City mine_....__...... 122,124 Faults: 92,126,127,138 Valley View mine. _ -_--...-.... 122,124 bedding-plane, defined_....____ 94 Top Slit (No. 9).. 80,90,107,126,127, 128, IS 8 Williamstownmine...... /22.124 occurrence__..______... 109 Tracy (No. 16)...80,91,126,129,130,131,138 Coal Mountain...... 71,73,74,82,97,107 description______93 Tunnel (No. 19)._..._..... 80,87,89,126 Coal Mountain fault complex______107,108 high-angle, in northern p art of area ___ 108 Twin...... _...... 126,129,130 Cobleskill Limestone, N.Y...._-.-...... -. 17 high-angle reverse, defined______... 93 Upper Four Foot (No. Wtf)...... 80,126 Cockle coal bed______. _ 130 description__..______105 6 L ....__..__._____...... 80,126 Coeymans Limestone Member of Helderberg low-angle folded thrust______94,97,99 7 L...... ___._...... _....__ 80,126 Formation___.__...._. 17,19,20 low-angle nonfolded thrust and under- S>4...... 80,126 Colkietmine._...... __...... 127,128 thrust__.______.__.__ 102 10L. _____..__...... _..... 80,126 Colton, G. W., cited ... . 19,115 tear, defined______84 13}£_.. . _ 80 Conemaugh Formation______79,82,131 occurrence______108 UM--...... - ...... 81,126 Conlin, R. R., cited... .._ _.... 15 thrust, defined...... _.__.______83 \4^i...... 81 Conrad, T. A., cited_...__-----___----- 11,18 underthrust______.. 84,85 22 __...... __._____._.. 81,126 Cook Inlet area, Alaska...... 136,137 denned______.______83 22L. __.______...._ 81,126 Cooper, G. A., cited...... _--....._._ 16 Fauna, Helderberg Formation______... 21 23...... 81,126 Crosby coal bed___. ______128 Mahantango Formation.______.. 36 2S!^...... 81,126 Crystal Run anticline___..._ 86,88, 101,125,126 MarceUus Shale_____.______29 24-29...... 81,126 Crystal Run canyon______.. 80 Selinsgrove Limestone______.. 27 Lykens quadrangle__ 122,124,127,128,120,130 Shriver Chert... 23,24 9H- 127 D Tonoloway Limestone______IS Minersville quadrangle ____.. 122, Dalmatia...... -. .... 15,20,23,26,27,37 Trimmers Rock Sandstone...___ 40,41 125,126,127, 128, 12P, ISO Fisher Ridge...... -.. 33,35,36 Mount Carbon Member of Pocono Forma­ Dam syncline ...... 56,97,101,102,122,125,126 tion__._...... ___..._.. 121 Damascus Member of Catskill Formation....- 18, Fisher Ridge fault....__.__ __ 84 Pine Grove quadrangle______128,120 37,41,42,45,104 Fisher syncline_____...... 87 Pottsville Formation...... _...... 121,122 correlations.___.__.. _...----. 48 Fishing Creek....___...... 13 deposltional environment_...... _ -. 47 Folk, R. L., cited... . 13 Schuylkill Member of Pottsville Forma­ fossils ...... 47 tion______...._._ 121 isopach map___ 45 Forestville syncline-._ 88, 88,101,122,125 description______124 minerals.______..______... 47 Fort Littleton Formation _ __ 37 Lykens Valley No. I...... 74,124 pebbles in conglomerate_ ____... 47 Fossil plants: flora...... 78 thickness.__...... __-....____.. 46 Llewellyn Formation____-___ 80,52 Lykens Valley No. 1J^______74,124 Daniel coal bed______...... ____ 127 Pottsville Formation.. 83 Lykens Valley No. 2____....__ 74,184 Dan's coal bed___...._...... _._._ 128 Schuylkill Member of Pottsvffle Forma­ Lykens Valley No. 3_____...... 74,124 Darton, N. H., cited_.... . 10 tion... 78 Lykens VaUey No. 3}£____...... 124 Dauphin County, Pa.._...... 35,134 Sharp Mountain Member of Pottsville Sharp Mountain Member of Pottsvil le For­ anthracite ______.. 138 Formation- - 78 mation______121 average chemical analyses of breaker Tumbling Run Member o* Pottsville description______125 samples_ 135 Formation 78 Little Buck Mountain (No. 4)...... 77,185 chemical analyses of coal-bed samples 132 Fossils: Scotty Steel No. 2__...... 77,125 recoverable coal__ 13P Adiantttes spp__ 56 Seotty Steel No. 3__...... 77,125,126 Dauphin syncline.. 6, Alethopteris lonchitica...... - 83 Spechty Kopf Member of Catskill For­ 87, 89, 91, 82, 97, 103, 105, 107, 108, 109, serin...... 83 mation______121 114, 122,124. Aneimttes spp 78 Tower City quadrangle__ in, 124,128,128,130 Decker Formation of N. Y., N.J., and Pa. 17 Annulari sphenophylloides . : 83 Tremont quadrangle . __ 122,125, ISO Deep Creek______.. 82,94 steUata_____.._____ 83 Tumbling Run Member of Pottsville For­ Deep Creek syncline______... 86,90,81,94,95,96 Arthrophycus alleghaniesis...... - - 11 mation . ______121 Deep Creek valley______66 Asterophyllttes equisetiformis ... 83 description __ 122 Deformation, depth..____ .. 115 Aulacotheca sp__ 83 Lykens Valley No. 3^_....___ 72,122 Delaware Limestone, Ohio 29 Bowmanttessp...... 83 DeUviUe Sandstone_ 45 Cattipteridium pteridium__- - 83 Lykens Valley No. 3J6_.______72, 122 Dempsey, W. J., cited.. 115 sp 83 Lykens Valley No. 4...... 72, Des Moines Series____ 79,82 Cordattes sp___ 83 74,86,100,107,110,113,124,138 Devonian rocks______14,16,41 Damascus Member of Catskill Formation. Lykens Valley No. 5 72, thickness ._...... 8,17 Dolichopterus ostius...... - 86,100,107,110,113,122,138 Devonian System, description 17 Erettopterus sp_ Lykens Valley No. 6____ 72,110,113,12 2 de Witt, Wallace, Jr., cited... _. - 19 Eurypterusmaria...... ---- Lykens Valley No. 7______.. 72,122 Dirt coal bed . - 127,128 Hughmttlerfa shawangunk...... Valley View quadrangle ... 122 Donaldson syncline___ 87, 91, 97, 105, 106,107, 108, 110, 113,122,124 Hypatliyridina venustula...... 37, Coal maps______3 Drake, A. A., Jr., cited. . 64,78 Linopteris rubella...... ------Coal measures. ______6,79 , Mien.. 29 Mariopteris cordata-ooata... Coal mines, Pottsville Formation, East Brook- Dyer Run canyon. 86 eremopteroides...... side____.____._____ 131,132 Dyer Run fault______...... 86,88,100,117 muricata...... Schuylkill Member of Pottsville Forma­ tion, Brookside mine______124 E Lincoln mine______124 pygmaea...... Penag mine______124 East Branch Blackwood fault.. 103,104,108,108,117 sphenopteroides...... 83 Tower City mine______124 East Brookside mine__ 131,137 Megalopteria spp 79 INDEX 147

Fossils Continued Page Page Neuropteris clarksoni...... 83 Hooflander Mountain. .___.... 20,23,33,35,36 Lebanon Reservoir.. ..__~ 65 fdlcata...... 83 Hooflander Mountain anticline....____... 15, Lee Formation, Pa., W. Va., Va., Ky., anc* flexuosa...... ____ 82,83 16,17,22, 24,26,29,31,86,88,94 Tenn______70,78 grangeri...... 83 Hooflander Mountain syndine______86,94 Lehighton quadrangle. ____ .. 37,45,48,51 heterophytta...... 83 Hoskins, D. M., cited_ ...... __ 15 Lelar coal bed..__._.____. .__ 128 missouriengis...... 83 Lesley, J. P., cited.. 10,41,59,65,68,70 ovata...... 83 I Levant White Sandstone_ __ __ 10 pocahontas...... 78 Indiantown quadrangle______93 Lewis coal bed.-- - . ... . 130 rarinerste...... 79,82,83 Introduction....______3 Lincoln mine ...... 124,126,127 scheuchzeri ...... 83 Inwood Sandstone..______25 Line Mountain...... 55,56,58,59,62,96,99 tennesseeana...... 78 Irish Valley Member of Catskill Formation 18, Little Mahantango Creek___.. _ 82 tenuifMa...... 79,83 37,38, 40,41,42, 88,92,104,105 Little Mountain. 71,73,74,91,96.97,99 oermicularis...... 83 depositional environment___. _ _... 44 Little Mountain syncline- 86, 90,94, 101,122,125,126 Odontopteris spp . ...--.--..__... 83 isopach map_....____...... _.... 42 Little Orchard (No. 12) coal bed 129 Pecopteris arbarescens...... 83 regional cor relations_.____.__... 45 Llewellyn Formation... . . 6, candoGiana...... 83 thickuess_....___..____.._... 4® 78, 70, 87, 88, 90, 91, 92, 94, 93, 102, feminaeformis...... 83 Irving syndine___.______..- 93 104, 105, 107,109, 112, 116, 131. lamuriana...... 83 Isopach map: coal beds...... 79,80, 121,122 unita...... 83 Beckville Member of Pocono Formation. 59 average thickness and range.... 123 vesttta...... 83 Buddys Run Member of Catskill For­ description..__.... . 126 spp ...... 82 mation_____..__.___... 54 depositional environment______81 Pterygotus globiceps...... 11 Cherry Ridge Member of Catskill For- fossil plants..... 80,82 SiqiUaria sp .. 83 mation...__.._.______. 52 minerals_.... . 81 Sphenophyttum emarginatum...... 83 Damascus Member of Catskil L Formation. 46 thickness______. 79 majus...... 83 Honesdale Sandstone Member of Catskill See also Coal mines. oblmtgifdium...... __ __ 83 Formation .____...... 48 Llewellyn syndine... . 87,89,117,114 Stigmaria.-...... 126,127,128,129 Irish Valley Member of Catskill Forma­ Location and area.. 3 Stylonurus myops...... 11 tion-. .- 42 Locust Mountain anticline 86 Four Foot coal bed__.______--___ 128 Mahantango Formation__ 36 Longwood Formation, N.J., and N.Y__. 15 Frackvllle antidine...... 86,88,97,116 Mandata Member of Helderberg Forma­ Lorberry Creek______. 5 brakes, L. A., cited-_....__._...... 40 tion... 21 Lorberry fault .__-__.._ __ 102, J04 Marcellus Shale. ...._...... _... 29 Lorberry syncline._...... ___ ... 86,122,124 Q Montebello Sandstone Member of Mahan­ Gate coal bed. ______130 Lower Little Swatara Creek 82 tango Formation.....- .. 34 Lower Mine Hill fault- D1.102 Qeiger, H. R., cited.- ...... 8 Mount Carbon Member of Pocono Forma­ Qenesee Formation, N.Y_____...____ 41 tion-.. 63 Lower Kittanning coal bed, Allegheny Forma­ Geologic features, principal____...____ 7 Ridgeley Sandstone__.__ .... 24 tion... 78 Geologic structure...... ___. 8 Selinsgrove Limestone.___ . 27 Lower Rausch Creek. 89 Georges Head anticline___..._.__ 86,87,124 Sharp Mountain Member of Pottsville Ludlowville Shale.. 28 Glen Dean Limestone, Va______70 Formation_.____ . .. 75 Lykens quadrangle 17, Qlendower mine___._____..____ 90 Shriver Chert-_____._... . 23 45, 48, 51, 54, 55, 58, 66, 84, 86, 87,83, Gold Mine Bun mine______ISS Spechty Kopf Member of Catskill Forma­ 89, 91, 94, 95, 97, 98, 99, 105, 10'. 108. Goodspringmine.-_...... 125,126,127,129 tion.______.___ 55 110,112,113. Gordon fault______103 Tonoloway Limestone__ IS coal beds-. 122,124,127,128,1,^9,180 Qratz mine______108 Trimmers Rock Sandstone.. . 38 Lytlemine. m,130 Qratz tunnel..______... 97 Tumbling Run Member of Pottsville For­ Lytle shaft-- - 130 Great Valley__ 64,78,93 mation______71 Greenbrier Limestone, Pa., Md., Va., and M W. Va..- ...... 70 J Griswold Gap Conglomerate______60 Joesting, H. R., cited_...... 115,116 McKenzie Formation - 15 John Veith shafts. ._...... 91,127,130 Mahanoy Basin syncline. 86 Joliet antidine ... 51,58,86,87,89,97,107,122,124 Mahanoy City.___ .... 117 Haley, B. R., cited___.__.__.__.__ 65 Jolietmine ...... - 126,127 Mahanoy Creek... 66,82 Hall, James cited...... __...... __._ 28 Joints.-...... 110 Hamilton Group______._-...... 28,29,32 Jugular coal bed___. ___ 127 Mahanoy Creek anticline.. 86 Hans Yost anticline_____._..... 86,94,97,100 Jugular fault..... 00,700,117,127,137 Mahantango Creek 82 HansYost fault- .. 86, 99,100, 117 Jugular syncline ...... 86,97,100,101,125,126 Mahantango Formation___ .. 27,28 20,94 age____.... - 86 Harrell Shale ... 38,41 K Burket Black Shale Member.....__.... 57,38 correlation.. 36 Kalmia mine ______. . 122 depositional environment- - 36 Harrisburgarch______.____ 27 Kanawha Formation, W. Va., Va., and Ky 79 Hartnagel, C. A., cited...... 42 fauna..._ _ - __...- -- 88 Keefer mine-----___.____ 92 isopach map.. 36 Heckschervillesyncline.______86, Keith, Arthur, rated 8 90, 91,100,101,125,126,127,128,129 lower and upper members. 112 Keller, Fred, Jr., cited-. 115,116 lower shale and sandstone member.. 29 Heginsfault ...... 94,117 Kemble mine __ ___ 101 Heister coal bed..__.. ______..... 127 thickness_ SI Keyser Limestone - 16 Montebello Sandstone Member. 29,32, 35, 88,104 Helderberg Formation ...... __.__. 16,^7,18 depositional environment_ 17 Coeymans Limestone Member. .... 17,19,20 thickness- 36 thickness-..__ __ ....- -- 17 upper shale member___ 35,88,94,104 depositions! environment. __.. £1 Kindle, E. M., rated -__ - - 11 fauna_____....______.__.... 21 King, Elizabeth, cited 115,116 Mahantango Mountain. - 5,55,58,59,62,65,96 Mandata Shale Member...... 17,19,20,112 Kings Mill Sandstone and Shale.. 45 Mahanoy Mountain- 71.73,97 New Scotland Limestone Member._... 19,20 Klemic, Harry, cited.- . 51 Mamay, S. H., cited 82 Hendricks, T. A., cited ...... 135,136,137 Klingerstown quadrangle___ 16, plant identifications by - 83 Hentzes fault..______101,102,109 17, 19, 22, 26, 29, 37, 42, 53, 54, 58, 64, 66, Mammoth coal bed.. 127,128 High Falls Formation, N.J., and N.Y 15 86, 88, 91, 94, 95, 96, 112. Hinton Formation, W. Va.______... 70 Mammoth coal zone_____ 79,81,127,128,131, 188 History and methods, miuing______117 L Mandata Member of Helderberg Formation 17, Honesdale Sandstone Member of Catskill Lakmia mine______182 19,29,112 Formation-______-___ 18,4^,^8 Lebanon County, Pa_____ 35 isopach map.. M isopach map______48 anthracite______... 1S8 thickness.--.. M minerals______.____.__ SO chemical analyses of coal-bed samples. 1S2 Manlius Formation of N.Y., N.J., and Pa.. 17 pebbles in conglomerate______50 recoverable coal______189 Mann, L., cited____..._ 119 148 INDEX

Page Page Pebbles in conglomerate Continued Page MarceUus Shale...... 27,28,30,104,112 Mississippian rocks __... _._____ 41,65 Tumbling Run Member of P ittsviUe Forma­ fauna______...____. 89 thickness______8 tion______...._____._ 71 isopach map.. 89 Mississippian System. _____.._____ 58 Tuscarora Sandstone____.______10 thickness___ ....____. 89 Montebello Sandstone Member of Mahantango Pebbles in conglomerate sandstone, SehuylkiU Martinsburg Shale 8, 84 Formatioa...... 29,30,35, 88,104 Member of PottsvUle Formation__ 74 depositions! environment .... _ 9 isopach map______84 Pebbles in Ridgeley Sandstone._____._ 84 fossil fauna.____.__..______. 9 minerals______S4 PeUetier, B. R., cited __.. . 64,78 thickness.. ..__ 9 thickness______33 Penag mine______..____ 124,125,126 Mather, W. W., cited_____._...._.... 41 Montour anticline.______116 Pennington Formation, Va______70 Mauch Chunk Formation ...... _. 6, Mount Carbon Member of Pocono Formation. 68 Pennsylvania, structural proviices______118 64, 66, 88,90,94,112,114,116,117 coal beds______121 Pennsylvanian rocks______66, 115 age...... 70 thickness______8 cobbles in conglomerate of upper member.. 64,67 minerals______68 Pennsylvanian System______70 correlation______. 70 pebbles and cobbles in conglomerate_ _ 6S Peters Mountain___. __. ___ 55,58,59,62,65,84 deposition__.___.__...... 68 thickness...______68 PhUadelphia, Pa., shipment of coal to___ 117 lower member____...... _ 65 Mount Pleasant Conglomerate..______59 Phoenix Park anticUne______87 minerals______66 Mount Pleasant Red Shale.______57 Phoenix Park No. 3mine.-.______1SS middle member_ 66, 91,95,96,97,98, 99, 103,114 Moyer, F. T., cited ..____-_.__._ 119 Phoenix Park syncline______... 87 minerals.______68 Phoenix shaft___.__.______130 sections-______68 N Physical features______.. 4 upper member______67, 78, 97, 98,99,102 Necho Alien...... 117 PiUow quadrangle______17 minerals______------__... 68 Needmore Shale______#0,104,112 Pine Creek.._.______.__ 5,82 Mauchono fault ...._. . 94,95,98,114,116,117 depositional environment- .- 86 Pine Creek Gap_....______. 59 Medina White Sandstone__.____..-..-- 10 thickness-. --._. .. ..__.. 86 Pine Creek vaUey______._____ 66 Middle Branch coal bed______. _ 128 western Maryland- ______.__ 27 Pine Grove quadrangle______8, Middle Creek anticline__...... 87 Nevin, C.M., cited-. 115 10, 12, 13, 26, 29, 37, 42, 48, 55, 58, 62, Middle Creek mine...... 130 New Bloomfleld anticlinorium.... 84,85,86,114,117 80, 86, 87, 89, 92,103, 104,107,109. Middle Mine Hill fault...... 101,109 ancestral..______...__. 116 coal beds...._...... 128,189 Middle Split (No. 8J-0 coal bed . 128 New Boston syncline .____ . 86,97,103 Pine Grove syncline 35,37,38 42,45,89, 98, 105,108 Mill Creek...... 5,82 New Lincoln mine 126 Pine HiU mine. ______101,188 Mill Creek Gap___._...... 48,55,59,62 New Mines-- ____ . 128 Pine Knot mine- . 90,12f, 126,127,128, 188, 137 Mill Creek valley...... 103 New Mines anticline.._____ 87,101 Pitch coal bed . 128 Mill syncline______._____. .-. 93,105 New Ringgold__._____.._____._._ 93 Platt, Franklin, cited ...... 41,59 MiUer ,J. T., cited ...... 86 New River Formation______78 Platt, W. G., cited ...... 41,59 Mine HIU...... 73,74 New Scotland Limestone Member of Helder- Pocono-CatskiU Transition Group .. ___ 41,57,59 Mine HiU anticline__...... 86,101,125,126,128 berg Formation. 19, SO Pocono faUline______.______- 64,66 Mine HiU fault_...... 102,117 Newtownfault...... 89,99, 105,106,114. Pocono Formation..______.. 51,57 Mine Hill fault complex______99,101 Niagara Series_.______... 13 age and correlation... .. 66 Mine workings, condition______118 North Coal Mountain fault___._....___ 108 BeckviUe Member.. __...... __ - 69, 84 extent______118 North Hooflander Mountain anticline____ 86,94 coal beds_ _... 121 Minerals: North Little Mountain syncline 86,90,94,97 ion. Beckville Member of Pocono Formation-.. 61 North Sweet Arrow fault___.____._ 35,104 Mount Carbon Member .. 68 Bloomsburg Bed Beds. . __....___ 14 Northern Anthracite field. ______.__ 67 coal beds. ._ 121 Buddys Run Member of Catskill Forma- Northumberland County, Pa . 42 thickness-___...____ 63 mation______54 Pocono Plateau____ .... . _.. 45,59,113 Cherry Ridge Member of Catskill For­ O Pocono Sandstone . 41,59 mation.______53 PoUard, William______.______134,137 Clinton Formation______18 Oak HiU mine . 101,130 Port Ewen Limestone of Helderberg Group . . 22 Damascus Member of Catskill Formation. 47 Onondaga Limestone of N.Y_____ 27 Porter mine...... 92,122,124 Honesdale Sandstone Member of Catskill Ordovician rocks, thickness______7 Post-Ridgeley unconformity.. 26 Ordov i cian-SUurian unconformity-.... 7,9 Formation...______. 50 Pottchunk fault.. 97,99,103,105 106,107,114,116,117 Ordovician System. ______._. 8 Llewellyn Formation______81 imbricate faults from... 99 Mauch Chunk Formation, lower member. 66 Oriskany Group..______..__ 17,82 Oriskany Sandstone, N.Y...__...... 25 PottsvUle Formation_ 6,64, middle member. ...______68 70,87, 88,90,91,94,98,99,104,106,109 upper member...______68 Orwin fault . 107 Oswayo Formation. .. 57 age and correlation- 78 Montebello Sandstone Member of Mahan- coal beds ______. ______181,188 tango Formation.______84 Ouachita Mountains. . . 185 Outwoodanticline..____.__._____ 93,105 average thickness and ra uge 182 Mount Carbon Member of Pocono Forma­ cobbles.. 64,78 tion...._____.___ .. .. 63 deposition- . 77 Pottsville Formation______78 fall line 78 Ridgeley Sandstone..___.______26 Paleozoic rocks_... 116 fossU plants.____ 83 Spechty Kopf Member of Catskill For­ Parker, J. M., cited 112 minerals 78 mation...______56 Pat Martin coal bed______.__._ . 129 Pa., W. Va., Va., Ky., and Term.. 70 Trimmers Bock Sandstone.______38 Payne mine..______90 SchuylkUl Member_... 7J, 78,100,102 Tumbling Bun Member of Pottsville For­ Peacock coal bed .. 129 Coal beds . 121 mation______78 Peaked Mountain anticline__86, 90, 97,101,125,126 See also Coal beds, SchuylkiU Mem­ Schuylkill Member of Pottsville Forma­ Pebbles and cobbles in conglomerate, BeckviUe ber. tion______74 Member of Pocono Formation 60 Sharp Mountain Member. 74, 78,100,102,128 subgraywacke of Tuscarora Sandstone_. 11 Mount Carbon Member of Pocono Forma­ Coal beds 121 Mlnersville quadrangle...... --._...... 4, tion.._. ______68 See also Coal beds, Sharp Mountain 48, 64, 66, 77, 79, 80, 86, 88, 89, 90, Tumbling Run Member of PottsvUle Forma­ Member. 91, 97, 98, 100, 102, 103, 106, 107, 108, tion. _...... 78 thickness__-__ ?7 117. Pebbles in conglomerate, Buddys Run Member Tumbling Run Member. 67 coal beds...... 122,125, ISO, 127,128,129, ISO of CatskiU Formation_____.... 54 70,74,78,90,100,102,110 Minersville synclinorium______. _____ 58, Cherry Ridge Member of CatskiU Forma­ Coal beds . 121 66, 72, 79, 84, 85, 87, 88, 89, 91, 92, tion______68 See also Coal beds, Tumbling Run 93, 96,106,109, 114, 117. Damascus Member of CatskiU Formation.. 47 Member. ancestral,______.___ 116 Honesdale Sandstone Member of CatskiU See also Coal mines, SchrylkiU, Sharp Mines, principal underground______181 Formation.______50 Mountain, and Tumbling Run Mem­ Mining, history and methods______117 SchuylkiU Member of PottsvUle Formation. 74 bers. INDEX 149

Page Page Page PottsviUe quadrangle_ 68 Sharp Mountain fault_____._.__... 102, iOS Taconic orogeny . . 9 Powder Hill anticline___ _ - 86,97,100,125 Sharp Mountain Member of PottsviUe Forma­ structural features formed during .._. 84 Powell Creek valley______. 51 tion__..______- 74,78,100,102,128 Talus fields- ______82 Precambrian basement complex 115 coal beds...... 121 Taylor, F. B., cited...... __...... 11 Pre-Pocono unconformity . . 57,59,116 description__ __ 185 Taylor, B. C., cited______6 Pre-Bidgeley unconformity___ .__ 24 cobbles in conglomerate__..._ 75,76 TaylorviUe______-__- 64,66 Present investigation B fbssU plants______79 Thomaston mine______90,126,127,129 Previous work_ 6 isopach map____.__.. . 75 Tonoloway Limestone__.__.._ _ 15, 16 of W. Va. . 70 thickness______-__ 75 depositional environment- . __ ___. 16 Shawangunk Conglomerate...______11,13 fauna______16 Q Sheppard, B. A., cited_____._____ 112 isopach map. . . 16 Quaternary deposits, Sherman Mountain______71,73,96 thickness.______._ _ 16 thickness Shipment of coal to Philadelphia_____ 117 Tower City mine______92,122, 184, 126,127 B Shiro syncline__.______87,97,110 Tower City quadrangle .. . 26, Battling Creek...____.._ __ _ 5,55 Shiro tunnel______97 37, 46, 48, 55, 66, 86, 87, 89, 91, 92, 93, Battling Creek canyon______55,58,86,103 Shohola Formation, Pa., and N.Y____... 45 97, 98, 99,104,105,107,108,112. Battling Creek Gap______59 Short Mountain_____ 71,73,74,82,97,98,107,108 coal beds______188,124,188,119, ISO Battling Creek gorge______... . _ 84 Short Mountain fault______...__ 94, 109, 110 Tremont fault..______... 99,115, J06 Battling Creek syncline______58,86 Short Mountain mine ___ __ 122,124,126,127, 1S8 Tremont quadrangle.. _ _ .. . 53, Bauseh Creek______89,91,114 Shriver Chert__...__._____.___ 20,22 55, 58, 66, 80, 86, 88, 89, 90, 91, 94, 95, Bausch Creek fault complex__ ... .. J07.108 fauna. .______.______23,24 96, 97, 98, 99, 100, 101, 106, 107, 109, Bead, C. B., cited__.____.___ _ 78,82 isopach map______23 112,124,125. plant identifications by . 83 SUurian rocks______14, J6 coal beds______.____.. 122,125,JS0 Beading Prong _ ...... 64,78 thickness______.______7 Tremont syncline-______86,87,ftf,106 Bed Mountain fault__...... __ 99,105, 107, 130 SUurian System______. 9 Trexler, J. P., cited. ______42,53,55,59 62,72 Beeside, J. B., Jr., cited__._.__..._- 17,20 Smith, A. DW, cited_...... _ 129,137,138 Trimmers Rock Sandstone.. . .. 18, Regional tectonics_ . ... US , N.Y.. ______41 SB, 37, 41,42,51,92,94,1H, 105 Relation of fixed carbon to deformation...__ IS4 South Coal Mountain fault __.. _.__._ 108 depositional environment.-___.__ Ift Reservoir fault______.._ 102, 108,117 South Newtown fault__...... 91,92,99,105, 106 fauna .. __._...... 40,41 Bidgeley Sandstone____.__.... 13,23,24,104 South Wales coal field. _..______134, 1S7 isopach map______._____ 38 depositional environment_ __ _- SB Spechty Kopf Member of CatskiU Formation. 18, minerals______... 33 isopach map______..__ 84 41,B1,B8,63,BB,M thickness______.__ SS minerals______86 coal beds______121 Tryon, F. G., cited.____. ... . 119 pebbles.. ... _ . 84 correlation..____..______57 TuUy Limestone. 37,38,41 thickness- _ _.. _ . 84 depositional environment. -..-.... 56 Tumbling Run Member of PottsviUe Forma­ Boad metal.._. 139 isopach map_____.. ____.__ 55 tion_..._ 67, 70, 74,78,90,100,172,110 Boehester Shale______.__ 11 minerals...... _..______...... 56 coal beds... . 121 Boedersvffle anticline______13,29,89,93,105 Spohn coal bed_____.___. ... 130 description_ _ 188 Bogers, H. D., cited.______-__- 6,10,68 Sterretts Gap______.__.____.. 9 fossU plants.. _____ . . 78 Rohresville syncline...... 101,125,126,127 Stevenson, J. J., cited._.______6 isopach map .. . _ . 71 Bondout Formation of N.Y., N J., and Pa_ 17 Stone Ridge .. ..- 33 minerals______.__.__ 72 Rothrock, H. B., cited - 65 Stony Mountain__...... 71,73,74,82,97,98 pebbles and cobbles in conglomerate_... 71, 72 Round Head fault.__..._ _ _. 108 Strahan, Aubrey.. _.__ 134,137 thickness_.______.___._ 71 Ruedemann, Rudolph, cited...... _ 11 Stratigraphy..______8 Tunnel coal bed ______130 Structural history______116 Turner, H. G., cited 7,135,136,137 S Structural provinces, Pennsylvania.. 113 Tuscarora Sandstone_____.__ 40,84,108 Salem mine______130 Structure______.___ . 84 cross-stratification____.__.._ . 10 Salina Formation, N.Y., Ohio, and Mich..... 16 Structure sections.______.. 3 depositional environment. 11 Sand and gravel..______..__ 1S9 Seudberg anticline. .______._ 93 fossils.___.__ .___..__ 11 Schoharie Grit______..__ 26 Suedberg fault...... __..._..... 93 minerals in subgraywacke.... . 11 SchuylkiU County, Pa__..._.. 34,35,36,42, 184 Susquehanna Gap______9 pebbles in conglomerate.. _ 10 anthracite______138 Susquehanna Group___-... . 18 thickness__..__...... 10 average chemical analyses of breaker sam­ description__ . 37 Twin coal bed. ples______._ 1SB Susquehanna River_..___ 4,113 See Coal beds, Llewellyn Formation, Bud- chemical analyses of coal-bed samples. _ 132 Susquehanna Valley.______. 16 Mountain (No. 5). recoverable coal. ______- 139 Swartz, C. K., cited... 7,11,12,13,15,16,17,22,24,25 U SchuylkiU Gap______.__... 9,62,68,70,74,84 Swatara anticUne_..______86,88,101 Uhler, P. B., cited.. 15 SchuylkiU Member of PottsviUe Formation... 71, Swatara Creek_...__.__.___... 5,38,42,82 Ulrieh, B. O., cited...... 16 78,100,102 Swatara Creek Gap___.______- 48,52,59,62 TJmbahauer coal bed. coal beds . ... . 121 Swatara Creek gorge______.... 87 See Coal beds, Llewellyn Formation, Bud- description.. __ .... 124 Swatara Gap...... 9,11,13,25,33 Mountain (No. 5). fossil plants._ 78 Swatara HiU quadrangle..... 4,8,10,12,13,26,27,29, Unconformity: minerals...... _.______. 74 31, 37, 42, 46, 48, 58, 80, 84, 89, 92, 93, between BeckviUe Member of Pocono For­ pebbles in conglomerate and conglomerate 103,104,108. mation and Spechty Kopf anc" sandstone.______74 Swatara iron sandstone____ . 12 Cherry Bidge Members of CatsMT SchuylkiU Navigation Canal.. _ . 117 Swatara mining district.____ 6 Formation______.._ 59 SchuyUdU River______. __.... 4,38,73 Sweet Arrow fault.___.__ 33,35,102, 104, 114,117 between Bloomsburg Red Beds and SchuylkiU River Gap_.___.__ .... 48 Sweet Arrow fault zone. 15,16, 17, 26, 37, 38, 85, 87, Bidgeley Sandstone IS Second Mountain____ 5,45,48,51,55,59,62,93,109 89,90,92,93,103, 104, 108,114 between Cherry Ridge Member of CatskiU Selinsgrove anticline______..__ 116 Sweet Arrow Lake....____ 31,33 Formation and Pocono Formation. 51 Selinsgrove Limestone______26,104 Swope anticline.....__...... ___ 93,108 between Martinsburg Shale and Tuscarora depositional environment. .____....-- 27 Swope fault.__._.....__.. - - 93 Sandstone____ _ . 9,10 fauna______#7 between Pocono and CatskiU Formations. 7 isopach map______-__ _. 27 Swope Mountain______29,33 between Spechty Kopf Member of CatskiU thickness______.__. 27 Synclines, Acadian______84 Formation and Pocono Formatter. 55, 57 Seven Foot coal bed______128 Synclines, description______.__ 90 Pre-Pocono_____...._-___- 57, 59,116 Shamokin__ ___..______.__ 117 Pre-Bidgeley-__.... 24 Sharp Mountain._ .. 5, T versus structural origin of Hegins1, 64, 67, 70,71, 73,74,77, 78,93,103,104, Taconic disturbance... 10 Mauchono, and Pottchunk dis­ 109,125, 188, 127,128. structural features. cordancies . 98 150 INDEX

Page W Page Page U.S. Bur. Mines, average chemical analyses Wadesvtilemine-._...... 101 White, I. C., cited..__...... __ 13,41,48,53,59 of breaker samples... 134,135 Wagner, H. C., cited _-__ .__...- 65 White Ash coal bed...... 127,128 White Horse fault . 93,108 chemical analyses of bed samples...... 132 Walcksvtile Sandstone Member of Catskill cited...__...... ___.. ... 119 Wiconisco Creek___.____.______. 82 Upper Little Swatara Creek ..... 82 Formation__.__. _____. 45 Willard, Bradford, cited...... 7, Upper Mauchono fault.-.. . 95,96 West Big Lick Mountain anticline____.... 86 26,29,32,34,35,36,37,42,45,48,51,53,57,58 Upper Mine Hill fault...... 101,102 West Branch Gap...... _.__. . 48,55,59,62,68 Williams, H. S., cited...... 42 West Brookside mine.__-______- 133 Williamstown mine_____ 107,108, US, 1&4, 126,127 West West Falls anticline__._ 86,94,95,96,97,101 WUlis, Bailey, cited ...... 6 Valley View mine...... 107,122,124,126 Western Middle Anthracite field __..... __. 67 Wills Creek Shale...... __.. IB Valley View quadrangle. . 37, thickness-____.______..__. 15 Westphalian zone A of Europe_ ... - 78 Wilmarth, M. G., cited....._ . 22 42,53,55,58,66,86,88,90,91,94,95,96,97,99 Westphalian zone D of Europe_ ..._... 79 coal beds...... _ 122 Wind gaps______..___._____..__. 5 Vanuexm, Lardner, cited.. . 22,28,41 Westphalian zones B and C ___.. _ - 79 Wood, G. H., Jr., cited...... 53, Ver Wiebe, W. A., cited_ . 115 Westwood mine...... _...... 92,126,127 55,59, 62,70,72,73,74,79,113 Vernon Shale of Salina Group, N.Y_ _. 15 White, C. D., cited...... 6,7,57,70,82,134,137 Woodmont Shale, Md. _. _. ______41