BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA Vol. 39. pp. 1031-1072 December 30. 1928

AGE OF THE FOLDING OF THE OKLAHOMA MOUNTAINS— % THE OUACHITA, ARBUCKLE, AND WICHITA MOUN­ TAINS OF OKLAHOMA AND THE LLANO-BURNET AND MARATHON UPLIFTS OF TEXAS 1

BY SIDNEY POWERS 2

(Presented by title before the Society December SI, 1927)

CONTENTS Tage Introduction ...... 1031 Stratigraphy ...... 1036 The, Ouachita Mountains ...... 1037 Problems...... 1037 Age of the Carboniferous sediments ...... 1038 Origin of the “glacial” boulders ...... 1042 Date of the folding and overthrusting ...... 1047 The Arbuckle Mountains ...... 1049 The Wichita Mountains ...... 1056 Former extent ...... 1056 Criner Hills ...... 1057 “Red Bed” syneline west of the Criner Hills ...... 1059 Red River-Gainesville uplift ...... 1060 Geologic history and geographic extent ...... 1062 The Llano-Burnet uplift ...... 1062 The Marathon uplift ...... 1066 The Ancestral Rocky Mountains...... 1068 Summary ...... 1069

I ntroduction

This paper discusses the folding, in Carboniferous time, which resulted in the Ouachita, Arbuckle, and Wichita Mountains and the Llano-Burnet and Marathon uplifts (see figure 2). A new name, the Oklahoma Moun-

1 Manuscript received by the Secretary of the Society December 31, 1927. 2 Published by permission of Mr. E. De Golyer, President of the Amerada Petroleum Corporation of Tulsa, Oklahoma. LXVII— B ull. Geol. Soc. Am., Vol. 39, 1927 (1031)

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CORRELATION CHART

MARATHON U PLIFT ARDMORE BASIN ARBUCKLE MOUNTAINS OUACHITA MOUNTAINS GLASS MOUNTAINS BETWEEN ARBUCKLES SOUTH-CENTRAL OKLA. WEST TEXAS BASIN AND CHINER HILLS WESTERN OKLAHOMA

lesse y fm. E l t f f S : Quartermaster fn Quartermaster fm. Big gasin fm. 1032 Cloud Chief , s Hackberry fm. Pecos Red Beds Oav Cr. dolomite 1 f

MSS Delaware Mt.fm. gci'sRh”- il Blaine Gypsum Chic kasha fm. Chickasha fm. S IN A T N U O M A OKLAHOM OF FOLDING OP ------AGE S R E W O P S. Leonard fm. Harper ss. San Ar>ylo fm Wellinqtonfm. Clear Fork fm. Ted beds" Marlon Group wichita-Albany Wichita fm. Chase Group ^ rWijtoBiQ L'rr.el Council Prove gp Council Grove qp. i Putnam fm Pontotoc Group Pontotoc Group Neva Is. Wabaunsee qp Pawhuska fm. Shawnee qp Ada fm. NeVagoney fm. Douglas qp. Va moo sa fm Lansinq qp. Ochelata fm Upper Gaptank fm Magdalena Is. Nellie Biv fm. Kansas City fm »¿fry,. Hogshocfter Is. Francis fm. Coffey ville fm Lenapah is. Nowata sh. Aitamont Is. bandera sh. Pawnee is. PENNSYLVANIAN Labette sh. “To; Wetumka sh Fört Scott Lower Gaptank fm. Canyon Group Cherokee fm. Cherokee fm.

savanna ss McAiester sh. Milisap ..... Lower Glenn fm. Hartshorne ss. Raymond fm. (Lower strawn) D im p le fm . Otterville I». wapanucka is. M orrow fm.

(Springer fm) (Springer fm)

(Helms Group) can ey sh . , Pitkin Is. caney sh Jackferk ss. ' &V4sviiie*s*h' Stanley sh. Hot Springs si Sycamore Is. Woodford Chert 3 (Vfoodford chert) Caballos novacoUte - s ffrlsco.frn. ■jv Arkansas novaculite I Bols d Arc is. ®jHaragan sh. c. Henryhouse sh. St.Clair Is Chimneyhill Is. ? I (.Chimney hill Is Blayl ïlJpçlkCk.sh. Maravilla» fm »*V' 3 3 jBigfork chert

■Wilcox' sands) St Peter ss. f Borgen ss.i Marathon series Ellenburqer Is.

B re w ste r fm H ickory ; Reagan ss. PRE-CAMBRIAN Schist, granite 6 ranite _i ------CONFORMITY ------UNCONFORMITY »IMPORTANT FOLDING

F ig u r e 1.— Correlation Chart of Formations in Kansas, Oklahoma, Texas, and southeastern Neio Mexico The chart is based on charts of the U. S. Geological Survey, with revisions especially by B. H. Harlton. The age of the Stanley, Jackfork, and Caney is doubtful. INTRODUCTION 1033

tains; is introduced to designate all these ranges.3 The Ozark Mountains are not included because they are essentially a part of a broad dome that extends from southeastern Missouri far west into Oklahoma, and that has undergone, uniformly, throughout its extent, broad periodic tilting and gentle folding unlike the sharp folding of the mountain

F ig u r e 2.— Outline Map of Oklahoma and Texas Map shows the principal mountain ranges exposed at the surface and those which have been found by the drill.

masses on the south. Llanoris4 is discussed because of its bearing on the folding of the adjacent mountains.

3 The Ouachita Mountain system of R. T. Hill (Physical geography of the Texas region, Top. Atlas U. S., U. S. Geol. Survey Folio No. 3, 1900, p. 3) included the Massern Ranges (now called the Ouachitas), the Arbuckle Hills, and the Wichita Mountains. Hill first described these mountains in the Annual Report of the Arkansas Geological Survey for 1888, vol. 2, 1888, p. 10. 4 Charles Schuchert has introduced endings in is for former land areas, in his “A Textbook of Geology,” part 2, revised edition, 1924.

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Only the movements in Carboniferous time are considered. Earlier movements in southern Oklahoma, except, possibly, an upwarp of the western part of the Wichita Mountains, were of minor effect. In the Arbuckle Mountains the top of the Hunton limestone is in places missing and its absence indicates movement; in Texas there is a hiatus between the Silurian (Hunton?) and the Mississippian limestone (of Boone age) which indicates a movement in Llanoris, on the east. The earlier mountain systems were no doubt slightly different in posi­ tion and configuration from those now existing. The Ouachita géosyn­ clinal prism of accumulation, probably lay southeast of the present Ouachita Mountains. The beds were folded and afterward overthrust to the north. A hypothetical uplifted mountain mass, called the pre- Ouachita uplift, composed of rocks like those in the Arbuckle Mountains (or perhaps a part of the Arbuckle Mountains themselves), probably existed in Mississippian time where the present Ouachitas are. Originally the Arbuckle Mountains occupied a larger area than they do now, extending westward as far as Pauls Valley, northward beyond Seminole, and southeastward to Durant. The Wichita Mountain system extended eastward from the New Mex­ ico line to beyond Gainesville, Texas. Its north rim was a line of lime-" stone hills, most of them now buried, which ran from Gotebo past the Criner Hills. Its south rim, which was far more complex in structure and probably included several faulted anticlines, extended from Foard County, Texas, on the west, to and beyond Cooke County, on the east. A branch (the real south rim) ran northwestward past Nacona, Texas, and Waurika, Oklahoma. The Llano-Burnet, or “Central Mineral,” region is an area of gently folded and highly faulted Pennsylvanian and older rocks, which are overlapped on the south and east by Cretaceous beds and on the west and north by early and middle Pennsylvanian beds ; so that it represents only a fragment of a once extensive domal uplift, which rose like a horst and withstood fairly well the ravages of diastrophic movements, although it is now a topographic depression. The Bend Arch forms the north flank of the uplift. The Marathon region in Texas appears to show a western extension of the folding of the Oklahoma Mountains, while the Glass Mountains, but not the folds of the Marathon uplift, are related to the Ancestral Eocky Mountains. The Solitario dome is in the farthest southwest “window” of the Oklahoma Mountains. It is thought that the beds in the pre-Ouachita uplift, which are com­ posed of rocks like those of the Arbuckle Mountains and are now covered

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by the Ouachita Mountains, were folded first, and that the movement is recorded in conglomerates in the Caney shale and Wapanucka limestone (Mississippian and early Pennsylvanian) of the present Ouachita Moun­ tains. Next rose the Wichita Mountains, as recorded in conglomerates above the Wapanucka (Otterville) limestone on the east side of the Criner Hills. The main Wichita folding came somewhat later, as is shown by gravel in the Glenn formation (early Pennsylvanian). Con­ comitantly the eastern and northeastern sides of the Arbuckle Moun­ tains and the Llano-Burnet region, including the Bend Arch, were up­ lifted. The folding of the Wichita Mountains and of the northeastern side of the Arbuckle Mountains continued spasmodically through Penn­ sylvanian time, the structural features now revealed having been com­ pleted in middle or late Pennsylvanian time. In late Pennsylvanian time the rocks were greatly eroded and at the end of Pennsylvanian time limestone conglomerate containing some granite pebbles was deposited around both mountain systems. The folding of the Ouachita Mountains occurred before middle Penn­ sylvanian time and was followed somewhat later by notable overthrusting of the sheet (Decken) type, probably at about the same time as the major folding of the Arbuckle Mountains. Similar compressive forces produce different types of structure in different geosynclinal prisms—in one of 8,000 feet of limestone overlain by shale as contrasted with one of 21,000 feet of sliale, sandstone, and chert but no limestone. The overthrusting of the Ouachita Mountains and the final folding of the Arbuckle Moun­ tains may therefore have resulted from the same crustal compression. Between the Arbuckle and Wichita Mountains the sediments of the Ardmore basin, of Pennsylvanian age, were folded sharply by regional compression toward the end of the Pennsylvanian time. In late Pennsylvanian time there was folding also in the Llano-Burnet and Marathon regions and in the Pennsylvanian outcrop area between Llano-Burnet and the Red River uplift, but it was not so pronounced as that in Oklahoma. Intense folding in the Marathon area at the end of Pennsylvanian time was followed by refolding early in Permian time. The folding in Permian time was a reflection of what had gone before. Folds between and over buried hills in the older rocks fade out as the thickness of the Permian section increases. The Anadarko trough north of the Wichita Mountains is one of the large structural features developed during or after the Permian epoch. It includes anticlinal folds such as that at Cement. On the other hand, erosion on the flanks of the Wichita Mountains in pre-Permian time produced many isolated knobs and ridges like those seen there today, but not all of those that are still

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covered by Permian rocks are reflected in the present structure. The basin in western Texas beneath the Llano Estacado is a similar Permian basin. After Cretaceous deposition and probably during Oligocene time there was folding, such as that seen in the Preston anticline, but this is an exceptional occurrence, because there is no structural reflection in the Cretaceous strata of the anticlines in the older rocks in Montague and Cooke counties, Texas. Cross-sections of the mountain areas (see figures 4-6 and the paleo- geographic maps, figures 7-11) are given to show more clearly the con­ ditions described briefly in the text. Several summaries of the literature and some interpretations of orogenic movements have been made, notably by McCoy5 and Miser,6 and this paper merely brings the discussion of the subject up to date.7 The writer wishes to express his gratitude for discussions of these problems to H. D. Miser, J. A. Taff, E. 0. Ulrich, P. V. Roundy, C. W. Honess, F. B. Plummer, C. W. Tomlinson, Ralph A. Birk, Sidney Paige, J. Y. Howell, J. L. Ferguson, and R. C. Moore. The micropaleontologi- cal determinations have been made by B. H. Harlton, of the Amerada Petroleum Corporation, who has described some new species in the Jour­ nal of Paleontology.

S tratigraphy

The stratigraphic sections in the Arbuckle and Wichita areas are similar and are comparable to those in the Ozark uplift on the northeast, and those in the Llano-Burnet uplift on the southwest. In all these areas lower Paleozoic limestone was deposited over a broad region whose structural axis ran from northeast to southwest (see figure 7). The sec­ tion in the Ouachita Mountains is very different. Here shale, sandstone, and chert appear instead of limestone; yet the Arbuckles and the Ouachi- tas are now only 15 miles apart. If the intervening mantle of Cretaceous sandstone should be removed we should probably find that the beds in the Ouachitas are overthrust on those in the Arbuckles.

5 A. W. McCoy : A short sketch of the paleogeography and historical geology of the Mid-Continent oil district and its Importance to petroleum geology. Bulletin Am. Assoc, of Petroleum Geologists, vol. 5, 1921, pp. 541-584. 6 H. D. Miser: Llanoria, the Paleozoic area in Louisiana and eastern Texas. Am. Jour. Sci., 5th ser., vol. 3, no. 8, August, 1921, pp. 61-89. 7 Since this was written a new set of paleogeographic maps of Oklahoma has been published by C. N. Gould and R. A. Wilson, Upper Paleozoic rocks of Oklahoma (Okla­ homa Geol Survey Bull. 41, (1927), and another set by R. H. Dott, Pennsylvanian paleogeography, with special reference to south-central Oklahoma. Idem, Bull. 40J, 1927.

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The correlations shown in figure 1 follow in general the correlation chart prepared by the U. S. Geological Survey in 1925,8 supplemented by the results of investigations made by B. H. Harlton of the micro­ faunas and by P. B. Plummer of the macrofaunas and by the results of lithologic work done by C. W. Tomlinson, Ralph A. Birk, and the writer.

The Ouachita M ountains

p r o b l e m s The Ouachita Mountains extend from Atoka, Oklahoma, to Little Rock, Arkansas, a distance of 225 miles, and are 50 miles wide. They are bounded on the north by the Arkansas Valley and in Oklahoma are sharply defined by the Choctaw fault for more than 120 miles. Their southern and eastern sides are overlapped by Cretaceous and younger formations. Topographically, the Ouachita Mountains in Oklahoma are a unit; but geologically they are two units,9 separated by the Ti Valley fault that lies north of Winding Stair Mountain and its extensions toward the southwest (see figures 3 and 4). The rocks north of Winding Stair Mountain may all be assigned to the Woodford, Caney, Wapanucka, and Atoka formations. The rocks on the southeast of Winding Stair Moun­ tain consist of Arkansas novaculite and older rocks—the Stanley, Jack- fork, Caney, Wapanucka, and Atoka formations. Sections in the south­ ern unit measured near Hot Springs, Arkansas, show about 5,000 feet of pre-Carboniferous shale, chert, sandstone, and novaculite,10 and columnar sections measured in Le Flore and McCurtain counties, Oklahoma, show about 4,700 feet of similar rocks.11 In both units the detrital material that formed the sediments was derived from rocks on the south, in Llanoris.12 The Carboniferous section is thickest in Oklahoma, where it is believed to have a maximum thickness of 23,000 feet,13

8 Published in index to the stratigraphy of Oklahoma, by C. N. Gould. Oklahoma Geol. Surrey Bull. 35, 1925. The Frisco formation, a t the top of the old “Hunton limestone,” was added by C. A. Reeds: The Arbuckle Mountains, Oklahoma, Nat. Hist. (New York City), vol. 26, 1926; The Arbuckle Mountains, Oklahoma Geol. Survey Circular 14, 1927. 8 E. O. U lrich: Okla. Geol. Surrey Bull. 45, 1928. 10 A. H. Purdue and H. D. Miser: Geologic atlas of the United States, U. S. Geol. Survey, Hot Springs Folio, (No. 215), 1923. 11C. W. Honess: Geology of the southern Ouachita Mountains of Oklahoma. Okla­ homa Geol. Survey Bull. 32, 1923. 12 H. D. Miser : Llanoria, the Paleozoic area In Louisiana and eastern Texas. Am. Jour. Sci., 5th ser., vol. 3, no. 8, August, 1921, pp. 61-89. Charles Schuchert: Op. cit. H. D. Miser and C. W. Honess: Carboniferous rocks of the Ouachita Mountains. Okla­ homa Geol. Survey Bull. 44, 1927. 13 C. W. Honess: Geology of southern Le Flore and northwestern McCurtain counties, Oklahoma. Bureau of Geology (Norman, Okla.), Circular 3, 1924. Geology of the southern Ouachita Mountains of Oklahoma. Oklahoma Geol. Survey Bull. 32, 1923.

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comprising the Stanley shale, Jackfork sandstone, Caney shale, and Atoka sandstone, which are also supposed to have been derived from material carried from Llanoris and laid down as delta deposits.14 Several major problems regarding the Ouachita Mountains have yet to be solved: (1) The age of the Carboniferous sediments; (2) the origin

F ig u r e 3.— Outline Map of the Ouachita Mountains in Oklahoma The map shows the principal overthrust faults and the outcrops of boulder-bearing Caney and Wapanucka shale. The eastern end of the Arbuckle Mountains is shown on the western side of the map. The locations of sections in figure 4 are given. The center of the Potato Hills is a “fenster,” surrounded by the trace of the Winding Stair fault as determined by H. D. Miser. The Ti Valley fault, on the north side of Winding Stair Mountain, is after Miser. The northern unit of the Ouachita Mountains is be­ tween it and the Choctaw fault.

of the “glacial” boulders; (3) the date of the folding and overthrusting. An hypothetical solution of each problem is as follows, without details, which can be obtained from the papers cited:

AOE OF THE CARBONIFEROUS SEDIMENTS The chert that forms part of both the northern and the southern unit of the Ouachitas can be identified in the northern unit, at Bengal, by

14 C. W. Honess: Idem, p. 22 ; also Miser, op. cit.

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its fossils as the Woodford chert; and in the southern unit, by its lith- ology, as Arkansas novaculite, possibly in part of Woodford age. The chert is separated from the overlying Carboniferous sediments by a dis- conformity or an unconformity. Conglomerate consisting exclusively of chert pebbles rests on the Arkansas novaculite in the Potato Hills.15

SEC.A-A'

MT. SECTION PRE” OUACHITA UPLIFT

WINDING STAI BENGAL

•Scales : Horizontal 5 miles Vertical - Diagram ma tic

F i g u r e 4.— Cross-sections of the Ouachita Mountains on Lines shown in Figure 3 and Cross-section of the Arbuckle Mountains and- Criner Hills The Ouachita Mountain sections are diagrammatic to indicate the nature of the over­ thrusting and the possible location of the pre-Ouachita uplift under the sole of the Choctaw fault. Many of the minor faults may be interpreted as overturned folds. The Arbuckle Mountain section show's the Criner Hills, Ardmore Basin, Mannsville inlier of the Arbuckle Mountains, and the small, low folds which characterize the Ordovician limestones of these mountains.

Elsewhere an unconformity can only be inferred, but in the northern unit the Caney shale appears to lie on different members of the chert at dif­ ferent exposures.

15 H. D. Miser : Oklahoma Geological Survey Bull. 44, 1927. Chert conglomerate is described by Honess near the base of the Stanley shale, in the southern part of the Ouachitas, in Oklahoma Geol. Survey Bull. 32, p. 192.

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In the southern unit the only inliers are the Potato Hills and the Black Knob Ridge, a ridge between Atoka and Stringtown. At these places and along the southeast edge of the core of the older rocks the chert is overlain by the Stanley shale. The age of this shale has not been satisfactorily determined. The fossil plants in it, as determined by David White,16 indicate Mississippian (Chester?) age; the invertebrates, as determined by Charles Schuchert and' E. 0. Ulrich,17 indicate earliest Pennsylvanian age. Harlton has found microfossils of post-Chester, pre-Pottsville age in basal Stanley shale in the Potato Hills. The Jackfork sandstone overlies the Stanley shale. Its age, as indi­ cated by its fossil plants, is the same as that of the shale. The thickness of the shale is about 6,000 feet; that of the sandstone is about 4,000 feet, and both thin toward the north. Caney shale containing “glacial boulders” overlies the Jackfork sand­ stone in Winding Stair Mountain, Johns Valley, and other synclines, but it has not yet been found south of Talihina. The type locality of the Caney shale is in Johns Valley, in sections 2, 3, 4, 9, 10, 11, township 1 south, range 16 east, Pushmataha County. Most of the shale is prob­ ably of Mississippian age,18 but the upper part (the Springer formation) is regarded as Pennsylvanian.19 Microfossils collected at Johns Valley and elsewhere are post-Chester and pre-Pottsville (Bendian) in age, according to Harlton. Overlying the Springer in Winding Stair Mountain, and probably in other synclines where the Atoka is preserved, is the Wapanucka lime­ stone or its equivalent, a fossiliferous calcareous sandstone in the Bok- tukola syncline and both limestone and conglomerate in Compton Cut and the near-by Lambersons Spur limestone at Weathers and elsewhere. The Wapanucka contains “glacial” boulders in Winding Stair Mountain. The Wapanucka is of earliest Pennsylvanian age.

18 Personal communication from Mr. White December 21, 1926. Oklahoma Geol. Sur­ vey Bull. 32, pp. 176-178. Other determinations by Mr. White have been published by Miser in Bulletin 44, Oklahoma Geol. Survey. 17 U. S. Geol. Survey Geologic Atlas, Hot Springs Folio, no. 215, 1923, p. 9. C. W. H oness: Stanley shale of Oklahoma. Am. Jour. Sci., 5th ser., vol. 1, 1921, pp. 75-78. 15 G. H. Girty: The fauna of the Caney shale of Oklahoma. TJ. S. Geol. Survey Bull. 377, 1909. The Caney in the Arbuckle area is divided by the U. S. Geological Survey into a Mississippian member, equivalent to the Moorefield shale (Meramecian according to Ulrich), and (in the Ardmore Basin) a Pennsylvanian member, called the Springer. 19 E. O. Ulrich : Oklahoma Geol. Survey Bull. 45, 1927. Charles Schuckert: Text­ book of Geology, 1924, p. 343. Ulrich believes th at the Pennsylvanian in the southern unit of the Ouachitas carries Mississippian fossils transported from the Arbuckle area. He proposes a new name, “Johns Valley shale,” for what he considers the Pennsylvanian part and from which Girty, Miser, and Honess have collected Mississippian macro­ fossils. Schuchert introduced the epoch Bendian to include formations from the Stanley to the Upper Caney (Springer), inclusive, and the Bend series. The Bendian epoch is transitional between the Mississippian and Pennsylvanian.

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The highest formation in the Ouachita Mountains is the Atoka, which consists of sandstone and shale. The upper part of the Jackfork of Honess 20 is Atoka. In the Boktukola syncline the Atoka is 7,000 feet thick. Its age is lower Pennsylvanian (Pottsville). Two beds of conglomerate are exposed on the Kansas City Southern Eailroad a mile south of Stapp (southwest ^4, section 7, township 3 north, range 26 east, 10 miles from the Arkansas line. The thickest bed measures more than 15 feet, but its base is concealed. The boulders of black chert and Ordovician limestone in this conglomerate are rounded and are tightly cemented in a sandy matrix. They are 4 to 6 inches in diameter and the largest is a foot long. Although this locality is mapped as Caney, the sandstone here21 indicates that it is Atoka. Black shale in a railroad cut in section 16, township 3 north, range 26 east, 21/2 miles southeast of the conglomerate, has yielded a Pennsylvanian micro­ fauna. Caney shale containing boulders several feet long is exposed both east and west of Stapp. In the northern unit of the Ouachita Mountains the Stanley and Jackfork are probably absent and the sandstones are probably Atoka. This suggestion is made because it seems to be justified by the field evidence and because it simplifies the interpretation of both the stra­ tigraphy and the structure. The Woodford chert crops out half a mile west of Bengal (in the center of section 11, township 4 north, range 21 east) and at Wesley (east y2, section 36, township 2 north, range 13 east), and chert, prob­ ably of the age of the Arkansas novaculite (including the Woodford), crops out at two other localities—at the new Pulcher place, in the center of section 8, township 3 north, range 17 east and at Pine Top school- house (Brushy Creek), in sections 4 and 5, township 2 north, range 15 east. It is overlain by Caney shale. The age of the chert here, as at all other Ouachitan localities, is disputed, but is considered Mississippian by Girty and Ulrich. The shale is found at all the localities named except Bengal and Pulcher. It is found also at the Allen place (north­ east !/4, section 20, township 3 north, range 16 east) and near Recyl (section 25, township 4 north, range 17 east). “Glacial” boulders are found only at the place last named, south of Recyl (Higgins).

20 Bureau of Geology Circular 3, 1924. H. D. Miser in Oklahoma Geol. Survey Bull. 35, 1925, p. 37 (footnote). 31 In a letter to the writer dated January 28, 1927, J. A. Taff states that these boulders are in the “basal or lower portion of the Atoka,” and that similar well-worn and reworked boulders occur in the basal Atoka near Compton.

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Wapanucka limestone has been found only at Wesley and was prob­ ably either not deposited at the other places or it has been removed by erosion. Sandstone and shale of the Atoka formation overlie the Wapanucka both south and northwest of the Choctaw fault. The absence of Stanley and Jackfork may be due to their deposition far south of their present outcrops and to extensive overthrusting, which conceals the transition. An enormous thickness of sediments (about 10,000 feet) must have been deposited in the Ouachita geosyncline south of the present Ouachita Mountains, while the Caney and most of the Springer sandstones and shales were being deposited in the southern part of the Arbuckle geosyncline and while shale and some sandstone was being deposited in the'northern part of this geosyncline. Yan der Gracht, in letters to C. N. Gould dated July 7, 1926, and October 5, 1926, writes: “I have thought that it might be possible that the exotic (Ouachita) chert facies would be confined to the overthrust sheet, but where, in front of the same, the autochthon substratum is buried, the Arbuckle limestone facies of the Ordovician might still be represented. . . . The real thrust-plane, as now saved from erosion, lies considerably farther to the south and southeast of the Choctaw fault. . . . The original Ouachita geosyncline was (prob­ ably) deeper than that of the Arbuckles because of the deep-sea chert facies of the Ordovician and Silurian.”

ORIGIN OF THE “GLACIAL" BOULDERS Blocks of limestone and chert containing fossils indicating that the rocks are identical with formations exposed in the Arbuckles, and rang­ ing in age from Ordovician (Arbuckle) to Mississippian (Woodford and Sycamore) and Pennsylvanian ( ?), occur in the upper part of the Caney shale and in the Wapanucka formation of the southern unit of the Ouachita Mountains and in beds near Eecyl, probably of Wapanucka age, in the northern unit (figure 2).22 The boulders are found from the west end of the Ouachita Mountains, near Atoka, to the Arkansas line, a distance of 100 miles. They are sub- angular or rounded and mosts of them are corroded by solution. Their length ranges from about 2 inches to 50 feet or more and averages about

22 J. A. Taff: Ice-borne boulder deposits in mid-Carboniferous marine shales. Bull. Geol. Soc. Am., vol. 20, 1909, pp. 701-2. J. B. Woodworth : Boulder beds of the Caney shales at Talihina, Oklahoma. Idem, vol. 23, 1912, pp. 457-462. E. O. Ulrich: Revision of the Paleozoic system. Bull. Geol. Soc. Am., vol. 22, 1911, p. 352, footnote, p. 361; also, Bull. 45, Okla. Geol. Survey, 1927. H. D. M iser: Oklahoma Geol. Survey Bull. 44, 1927. G. H. G irty : U. S. Geol. Survey Bull. 377, 1909. Charles Schuchert: Text­ book of Geology, 1924, p. 370.

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1 foot. A few notably large masses have been found, most of them in Johns Valley, the first of which were discoveread by the writer in the fall of 1926. Other large boulders, which are about 25 feet long, are found in and near Compton Cut (sections 17, 18, 19, township 4 north, range 22 east) and at a place south of Eecyl, where one 20 feet long is exposed to a thickness of 10 feet. Johns Valley contains some of the largest of these detached masses of rock. Masses in conglomerate at Levis and Bic, Quebec, though much smaller, offer the same problem as to their origin. Many of the large masses in Johns Valley are apparently Viola limestone and contain abundant fossils interbedded and in place. They are believed to be at the same stratigraphic horizon, about 5 to 10 feet above the Jackfork sandstone, and to be underlain and overlain by Caney shale containing microfossils. The measurements of the exposed parts of certain masses are, approximately, 550 feet by 65 feet (stratigraphically, dip about 30 degrees) ; 200 feet by 150 feet, and 200 feet by 50 feet by 4 feet thick at one end. Small boulders of other kinds of limestone occur near these large masses.23 Stratigraphic arrangement of boulder beds in the shale is apparent in Johns Valley and between Compton Cut and Bengal. In Johns Valley there are two ‘‘boulder” beds, one near the base of the shale, which in­ cludes the enormous masses of limestone just described, and the other near the center of the valley, where the boulders are only 1 foot to 3 feet long and overlie a concretionary bed. North of Compton Cut there are three or four boulder-bearing beds, the lowest being near the top of the Jackfork. At other places there are no boulders in the lowest Caney black shales, and the overlying boulder-bearing shales are gray, not black. Boulders occur also in the Wapanucka, if this formation includes all the shale between the fossiliferous members and the first overlying sand­ stone (Atoka). The best-known locality is in Compton Cut, where R. C. Moore and H. D. Miser found Wapanucka fossils. The fossiliferous fine­ grained conglomerate is in the middle of the cut, where the relations are obscured by faulting and close folding. The boulders have been elon­ gated, slickensided, and grooved into each other by intense compression and shearing. A good exposure of Wapanucka limestone underlain by boulder-bearing Caney shale and overlain by boulder-bearing Wapanucka (or Atoka?) shale was found at Lambersons Spur, a mile south of Compton Cut, by

23 Detailed information concerning these boulders is being published by C. W. Miller in a Bulletin of the Oklahoma Geological Survey.

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H. D. Miser. The boulders above the Wapanucka are all less than a foot in diameter and are scattered through the shale as in a tillite. Some of them are embedded in the base of the overlying Atoka sandstone. Other exposures of boulders in the Wapanucka shale, with the same small-pebble chert conglomerate as in Compton Cut, are found overlying boulder-free Caney shale in the Winding Stair Mountain syncline north and west of Weathers, in section 26, township 3 north, range 16 east; southwest ^4 section 4, township 2 north, range 16 east. The writer has made no attempt to determine the age of the limestone in each boulder, but after visiting most of the boulder beds he has in­ ferred that the boulders were derived from different sources at different times. The fact that boulders of Arbuckle and Yiola limestone occur in the lowest bed indicates that the entire stratigraphic section was exposed when the deposition of the boulders began. Nowhere do the beds of the boulder-bearing shale contain sandstone, or even pockets of sand or small pebbles, but they do contain small-pebble conglomerate. All the boulders are surrounded by gray or black shale containing micro-fossils and, in places, macro-fossils. Numerous outcrops of the Wapanucka show scattered pebbles distributed through many feet of shale “like plumbs in a pudding.” Large fossils similar to those in the “Mississippian” Caney of the Arbuckles are seen at Allen, at Wesley, between the boulder beds in Johns Valley, and elsewhere. The origin of the boulders and large masses and their mode of trans­ portation are unknown. It is commonly held that they came from the Arbuckle Mountains, but there are no boulders in the Caney or Springer on either side of these mountains. Furthermore, these mountains were not folded until later. They might have been brought from the Criner Hills, which was a land area during part of Carboniferous time, but it is difficult to imagine their transportation across a placid sea whose sedi­ ments contain no boulders. An hypothetical southeastern extension of the Arbuckle Mountains, folded and being eroded at this time, indicates a landmass in the position supposed to have been occupied by the Ouachita seas. The exposure of the Caney in the Arbuckle Mountains that lies farthest east, 22 miles from the nearest boulder, contains no boulders and shows no evidence of an unconformity. The largest boulders are not at the western edge of the Ouachitas. A pre-Ouachita uplift (figure 8), exposing a small mass of rocks of Arbuckle type, may have been the source of the boulders. Such a mass would have been formed by the eastward extension of the Wichita- Arbuckle prism of sediments at a place near or south of the present Choctaw fault and near the center of the Ouachitas in a line from east to

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west. It would have been formed after the Woodford chert had been • deposited and probably during Stanley-Jackford sedimentation. It would have been high land in Caney time. All traces of this uplift would now be covered by overthrusts from the south (figure 3). Evi­ dence of land in the northern part of the Ouachita area of Arkansas in Devonian time is reported by Ulrich.24 Such an uplift would furnish a near-by source for the boulders, located centrally nearest the large masses. It would have stood north of the sea in which the Winding Stair and Johns Yalley black, boulder-bearing shales were deposited and possibly south of that in which the boulders near Recyl were deposited in Wapa­ nucka (?) time. The absence of boulders at other places north of Wind­ ing Stair Mountain is accounted for by unconformity, the Atoka resting in different localities unformably on Arkansas novaculite, Woodford chert, Caney shale, Wapanucka limestone, and Wapanucka (?) boulder beds. The size of the boulders diminishes from this area eastward to Arkansas and westward to Atoka. Some arguments against this hypothetical uplift are the following: (1) The Sycamore limestone, known as a thick bed only along the southern flank of the Arbuckles, must have been present; (2) conglomer­ ates should be found, but are known at the base of the Stanley only in the Potato Hills, in the Wapanucka of Winding Stair Mountain, and in the Atoka at Stapp; (3) shore conditions on the north are not shown in the Stanley or Jackfork. No theory as to the source of the boulders is fully satisfactory. The Arbuckle Mountains, 110 miles from the boulders on the Arkansas line near Stapp, must be excluded. A source in the southeastern extension of these mountains, which must be located close to or within the Ouachita sea,25 places sediments that contain different fossils too close together. The small boulders are nearest this hypothetical source of supply. How boulders and masses of rock over 550 feet long, 65 feet thick, and of great width could have been transported is another problem. An over­ thrust would move masses from which these “boulders” could have been derived, but it is more difficult to imagine an overthrust into the Caney

24E. O. U lrich: U. S. Geol. Survey Geologic Atlas, Hot Springs Folio (No. 215), p. 8. 25 A well in sec. 17, T. 4 S., R. 11 E., 12 miles south of Atoka and west of a pos­ sible hypothetical extension of the Choctaw fault below the Cretaceous, penetrated a typical Arbuckle section from Caney to Simpson. A well in the center of the Potato Hills, in sec. 30, T. 3 N., R. 21 E., 2,600 feet deep, does not show an Arbuckle sec­ tion. In Texas the Bailey Development Company’s well near Chicota, in Lamar County, entered schist at 1,880 feet; and the Lady Alice well, north of Clarksville, in Red River County, entered schist at 1,693 feet, directly under the Cretaceous.

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Sea than to imagine an uplift of anticlinal type, which is the typical structure of Arbuckle rocks. The Ouachita overthrust now visible' was much later and came from the south. An overthrust in Caney time would have come from the north, from an Arbuckle basin into a Ouachita basin. Overthrusting seems plausible until regional tectonics are considered, and no later overthrusting would account for the wide dispersion of the boulders. Overthrusting would furnish a block large enough to supply the masses in Johns Yalley, provided the overthrust of competent rocks over unconsolidated Jackford sandstone, with or with­ out a thin veneer of black shale, would not disturb the bedding of the sand and mud. It is conceivable, as R. C. Moore has pointed out to the writer, that the overthrust may have preceded Caney deposition, and that the shales may have been deposited around and even under the edges of the present masses, which would represent corroded fragments of the overthrust block.26 However, no traces of the rest of the original overthrust block in the form either of sand grains or small pebbles of limestones and chert have been found in Johns Yalley or elsewhere. Ice can move large masses of rock and can cause an assortment of sizes and kinds. Many of the boulders show the effect of solution, which would have removed glacial scratches. The boulders in Compton Cut show remarkable grooves and scratches due to squeezing and slickensiding, but none due to glaciation. Some other boulders, especially those found in the Wapanucka shale, show grooves and scratches that may be inter­ preted as glacial. Ice commonly furnishes not only boulders but till; yet floating ice may supply masses and solution may aid in rounding them. The material may be of several kinds and may be variously as­ sorted as to size. The consensus of opinion in the literature, except for the boulders at Compton Cut, is that they were transported by ice, but whether by floating or shore ice or otherwise is not agreed. If ice can not transport such enormous masses of limestone, each more than 200 feet long, overthrusting must have brought the limestone to Johns Valley, because the source of supply could not have been nearer than 20 miles. How the boulders were distributed over an area 100 miles long (a shoreline?) is still unknown. The absence of any evidence of stream deposits makes floating ice a convenient distributing agent. '

28 When Taff was mapping the Atoka Folio he and Girty found Ordovician limestone boulders (but not the large masses) in Johns Valley, and they concluded that the under­ lying Jackfork and Stanley were Ordovician. The Caney shale was named by Taff from a creek in this valley, now known as Johns Creek, and abundant macro-fossils were found above what is now known to be the stratigraphic horizon of the Ordovician limestone masses. Ulrich regards the Caney fossils as exotic.

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DATE OF FOLDING AND OVERTHRUSTING The date of the folding of the Ouaehitas can not be satisfactorily determined. The occurrence of boulders in the Caney fix the date of the first Carboniferous uplift as Mississippian—a local mountain-built uplift, possibly accompanied by overthursting and a gathering place for shore

Wic h it a M t . S y s t e m

^ -'S'

HORIZONTAL SCALE

F ig u r e 5 .— Cross-sections of the Wichita Mountain System, the Criner Hills, Llano- Burnet Uplift, and Marathon-Glass Mountains Uplift The Red River Arch south of Red River is considered to be a part of the Wichita system. The cross-section of the Criner Hills shows the unconformity and conglom­ erates which date the folding of the eastern rim of the original Wichita Mountain sys­ tem. The Llano-Burnet section is diagrammatic and foreshortened to show the prox­ imity to Llanoris and to the Balcones fault zone. Overlapping Pennsylvanian forma­ tions are shown at the north end of the section. The Marathon and Glass Moun­ tains show the older Pennsylvanian on the southeast and the Permian on the north­ west side away from Llanoris. Folding is comparable in intensity with that of the Ouachita Mountains, but overthrusts are not reported.

ice (figures 4 and 8). The next movement came in early Pennsylvanian (Atoka) time, contemporaneously with uplift in the Arbuckle Moun­ tains. It probably caused the formation of the McAlester coal basin,

LXVIII—B u l l . G e o l . S o c. A m ., V o l . 39, 1 9 2 7

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but uplift was limited to a very small area, as shown by the conglomer­ ates near Stringtown and Atoka. Taff27 found conglomerates composed of Talihina chert and Stringtown shale for a distance of about 12 miles along the strike and through 3,000 vertical feet of strata north and west

F i g u r e 6— Cross-sections of the lmried Amarillo Mountains These mountains are the western extension of the Wichita Mountains. The reflection of the buried granite range is shown in the structure of the overlying Pennsylvanian and Permian strata. Pennsylvanian and lowest Permian beds do not extend west as far as Bravo Dome (Section I). The easternmost section (IV) is of the Wichita Moun­ tains, south of Gotebo.

of Black Knob Ridge, in the Atoka, Hartshorne, McAlester, Savanna, and Boggy formations. A distance of only 4 miles across the Choctaw

21J. A. Taff: U. S. Geol. Survey, 19th Ann. Rept., pt. 3, p. 441, 1898. TJ. S. Geol. Surtey Geologic Atlas, Coalgate Folio (No. 74), 1901, and Atoka Folio (No. 79), 1902.

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fault separates the conglomerates from the cherts, hut there is no evi­ dence to show the original distance apart or the amount of lateral dis­ placement of these rocks. The absence of conglomerates elsewhere in the sediments north of the Ouachita Mountains shows that there was no general uplift until after Boggy time. McCoy28 believes that the change in the strike of the Pennsylvanian formations beginning with the Thurman sandstone, to­ gether with a marked change in the character of these sediments, indi­ cates a movement of the Ouachitas (see figure 9). The writer believes that at this time the Ouachita basin was folded, but that it was still south of its present position. Conglomerates are characteristic of the Seminole conglomerate, Ya- moosa formation, and Pontotoc group north of the Arbuckle Moun­ tains. Fragments of chert are the most common pebbles in the Seminole and Vamoosa, and granite pebbles from the Arbuckle Mountains appear for the first time in the Pontotoc. The overthrusting of the Ouachita Mountains to their present position can be assigned to Seminole time (figure 10), and some of the cherts may have come from these moun­ tains.29

T h e A r b u c k l e M o u n t a in s

The Arbuckle Mountains are in south-central Oklahoma, 15 miles west of the Ouachita Mountains and 55 miles east of the Wichita Moun­ tains. They are 65 miles long and about 35 miles wide. Drilling has not revealed extensions of the folding that would expand these dimen­ sions greatly, but gentle uplifts, such as that at Seminole, almost double the size ot the area directly affected by the orogenic movements. Columnar sections show 10,000 feet of pre-Carboniferous sediment, con­ sisting principally of limestone, but including some sandstone and a very little shale, all overlain by 7,000 feet of Carboniferous beds, consisting largely of shale, which is accompanied by some interbedded sandstone and a very little limestone. These beds include the Boggy formation only on the northeast flank of the fold and about 15,000 feet of deposit up to the Hoxbar formation on its south side. Structurally the Arbuckle Mountains consist essentially of three

28 A. W. McCoy : A short sketch of the paleogeography and historical geology of the Mid-Continent oil district. Bull. Am. Assoc. Petroleum Geologists, vol. 5, 1921, p. 562. 29 Extensive overthrusting was first postulated by C. L. Dake: The problem of the St. Peter sandstone. Univ. Missouri School of Mines and Metallurgy, Bull., vol. 6, 1921. See also H oness: Okla. Geol. Survey Bull. 32, p. 258, and Bull. 40 R., and Miser: Structure of the Ouachita Mountains of Arkansas and Oklahoma, Bull. Geol. Soc. Am., vol. 39, 1928.

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geanticlines in which relatively flat-lying Arbuckle limestone makes up the larger part of the beds, around which steeply dipping younger beds form hogback or cuesta ridges (figures 4 and 5). Granite is exposed in a large area only in the southeastern fold. The extension of the granite to the southeast beyond a place where it is found in a well near section 1, township 5 south, range 9 east, is unknown. If the axis of this fold

F ig u r e 7.—Paleogeograpliic Map of Oklahoma and Texas Sliows the Lower Ordovician Land (Llanoris), present outcrops, and the area of lime­ stone deposition west of that of shales, cherts, and sandstones. were prolonged to the southeast it would cross Eed Eiver near wells that found schist and would extend directly into the former Ouachita basin. The northern Arbuckle fold continues westward underground as far as Pauls Valley, and its north flank plunges northward gently until it flattens to form a structural plateau argund the Seminole and Wewoka

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oil fields—the Huriton arch of Dott. Prom these fields a buried ridge extends north past the Cushing oil field and parallel to the Nemaha Mountains. A subsidiary faulted fold farther south is called the Law­ rence uplift. The southwestern Arbuckle fold is faulted at its northwest end, where a buried fault block, in the Robberson field, was found by

Shows the outcrops of the Morrow, Wapanucka, Marble Falls, and Dimple forma­ tions and the outline of the sea in which they were deposited. The Nemaha Moun­ tains and Cushing Ridge, folded at or soon after the close of Mississippian time, were land areas. The Seminole uplift was covered by the Wapanucka series overlapping the older formations from the east. The pre-Ouachita uplift was a landmass supplying large boulders of Paleozoic limestones to the adjacent sea. The Wichita Mountains were probably just emerging. drilling. Another such fault block is exposed near Mannsville, east of Ardmore.30

30 C. W. Tomlinson : Buried hills near Mannsville, Okla. Bull. Am. Assoc. Petroleum Geologists, vol. 10, 1926, pp. 138-143.

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On the southern flank of the Arbuckle Mountains, near Ardmore, the Carboniferous sedimentary section appears to be complete, including the Caney shale, Springer formation, Glenn formation, and Hoxbar forma­ tion. The unconformities and conglomerates 15 miles farther south are not conspicuous north of Ardmore. NEMAHA MTS. GRANITE m©G£

F ig u r e 9.—Paleogeographic Map of Lower Pennsylvanian Time Shows outcrops of Boggy, Cherokee (Bartlesville), Lower Glenn, and Strawn forma­ tions and the connecting sea. The Ozark, Nemaha, Ouachita, part of the Arbuckle, Wichita, and Llano-Burnet areas were land and all but the Ozark Uplift had been ap-- preciably folded. The Cushing ridge was covered by a shallow sea. A delta south of Red River was being formed from Llanoris. The Marathon area may have been above the sea.

In the center of the Arbuckle Mountains the upper part of the Glenn formation is exposed in the Mill Creek syncline, where it is underlain by conglomerate. This outlier may be of the same age as the upper part of the Boggy formation north of the mountains.

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On the north and northeastern flanks of the Arbuckle Mountains the Atoka shale, equivalent to the lower part of the Glenn formation, is over­ lapped by the succeeding formations. Overlaps and conglomerates appear in each succeeding formation, in­ dicating frequent warping of the northeastern part of the Arbuckle

F ig u r e 10.—Paleogeographic Map of Mid-Pennsylvanian Time At the time of the greatest expansion of the Pennsylvanian seas in this area. The Ouachita Mountains were overthrust at this tim e; the Arbuckle and probably the Wichita and Amarillo Mountains were folded.

Mountains and of the larger uplifts in Boggy, Seminole, Vamoosa, and Pontotoc time. If the lower Glenn in the Mill Creek syncline is equivalent to the high­ est part of the Boggy, the rocks of the Arbuckle Mountains had been uplifted and eroded in lower Glenn time, so that all the Ordovician lime­ stones were exposed and their truncated surfaces were covered by the

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Boggy sea.31 About 10 miles farther south (north of Ardmore) no con­ glomerates are found. Therefore the first folding in the Arbuckle Mountain area during the Carboniferous period appears to have occurred

F ig u r e 11.— Paleogeographic Map showing Conditions at the Close of Pennsylvanian Time Most of western Oklahoma and Texas were the sites of deposition of red beds and salt. The Ancestral Rocky Mountains were elevated at about this time, as indicated in the Pedernal Hills. A large delta existed near the present Red River.

on the northern flank of the range during Atoka (early Glenn) time. Uplift in the form of gently warping was periodic and frequent until the great uplift at the end of the deposition of the Savanna sandstone. Fold­

81 The geological history of this area is ably described by George D. Morgan, who is followed here. Geology of the Stonewall quadrangle, Bureau of Geology, Norman, Okla. Bull. 2, 1924 ; also, by the same author Circulars 11 and 12 of the Oklahoma Geol. Survey, 1922 and 1923, and Circular 2 of the Bureau of Geology. 1924 (Boggy unconformity and overlap in southern Oklahoma).

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ing at this time affected the northern but apparently not the southern part of the mountains, and erosion through almost the entire Paleozoic section is recorded in the conglomerates at the base of the Boggy forma­ tion, formerly confused with younger conglomerates and called Franks. Upper Boggy shales covered a part of the uplifted area and are preserved in the Franks and Mill Creek synclines. A portion of the Arbuckles, the Lawrence uplift south of Ada, re­ mained a land surface (figure 9) until the deposition of the We wok a formation, or else the intervening formations were eroded before Wewoka deposition. Limestone conglomerates occur in the Wewoka formation, but the uplift indicated by conglomerates in the Seminole was more im­ portant (figure 10). Still more profound folding and faulting of the Arbuckle Mountains is recorded in the conglomerates of the Yamoosa formation. The conglomerates of the Pontotoc group were deposited at the end of Pennsylvanian time on the eroded mountains, which were folded and faulted as they are today (figure 11). Subsequent uplifts have been regional, consisting probably of broad doming of the moun­ tains, which increased the steepness of the initial dips of the Pontotoc conglomerates.32 Of these movements only the one preceding Pontotoc deposition is clearly recorded on the south flank of the mountains. Post-Permian movements caused gentle folding of the Arbuckle Moun­ tain region, but the details of the structure and the buried topography of the older rocks are not clearly recorded in the structure of the Permian beds. The geologic history at Seminole and Wewoka, north of the Arbuckle Mountains, is well known from drilling. The Simpson formation, which overlies the Arbuckle limestone, contains the “Wilcox” (Mounds) oil sands. The lithology and the thickness of the Simpson are variable. Regionally the Simpson, the Yiola limestone, and the Sylvan shale are conformable. An unconformity above the Hunton limestone is marked by extensive' erosion. The Chattanooga shale, equivalent to the Wood­ ford chert, has a uniform thickness throughout the area. The overlying Mississippian strata are Mayes limestone and Mississippian Caney Shale. Both are of uniform thickness over a broad area. The lowest Pennsyl­ vanian formation varies from east to west because of progressive over­ lap toward the west. Over much of the Seminole area the oldest Penn­ sylvanian is shale (Springer?), overlain by the Cromwell sand mem­ ber of the Wapanucka, and in turn overlain by the Wapanucka limestone,

32 R. A. Birk : The extension Of a portion of the Pontotoc series around the western end of the Arbuckle Mountains. Bull. Am. Assoc. Petroleum Geologists, t o I. 9, 1925, pp. 983-989.

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which thickens eastward. A pronounced unconformity separates the Wapanucka limestone and the overlying Pennsylvanian beds (Boggy), and very little of the detail of the structure can be told from the 3,600 to 3,800 feet of Pennsylvanian, principally because the westward tilting and overlap of these rocks effaced most of the folding that was reflected into them during late Pennsylvanian time and partly because no satis­ factory horizon markers are available for detailed correlations. In brief, the first folding at Seminole and along the Seminole-Cushing buried ridge took place during the Devonian period; there was warping before the deposition of the Wapanucka limestone, and the anticlines were de­ fined during the pronounced folding early in Pennsylvanian (pre-Boggy) time, and important refolding and tilting took place later in Pennsyl­ vanian time.33 The unconformities and disconformities are* rarely marked by conglomerates; in fact, conglomerates are seldom found in drilling throughout the Mid-Continent fields except on a sharp uplift like part of the Red River arch.

T h e W i c h i t a M o u n t a in s

FORMER EXTENT The Wichita Mountain system is believed to extend from New Mexico through the buried Amarillo Mountains and the present Wichita Moun­ tains to some point southeast of Gainesville, Texas. In Texas the Red River arch 34 and the buried hills ranged en échelon from Electra, Burk- burnett, and Petrolia through Nocona, and it is believed that certain unnamed hills near Gainesville are genetically connected with the Wich­ ita system (figures 4, 5). In Oklahoma, a corresponding row of buried hills, which extend from Fort Sill to the Criner Hills through Healdton and Hewitt, forms what is believed to be the north flank of the former Wichita Mountains.35 The geologic history of each area will be con­ sidered separately.

33 Sidney Powers : The Seminole uplift, Oklahoma. Am. Assoc. Petroleum Geologists Bull., vol. 10, 1927, pp. 1097-1108. E. H. Dott : Pennsylvanian paleogeography. Okla­ homa Geol. Survey Bull. 40J, 1927. A. I. Levorsen : Seminole County, Oklahoma. Idem, Bull., 40BB, 1928. M Lee Hager : Red River uplift has another angle. Oil and Gas Jour., October 17, 1919, pp. 64-65. P. V. Roundy : U. S. Geol. Survey .Bull. 726F, 1922, p. 293. Sidney Powers : Reflected buried hills and their importance in petroleum geology. Economic Geol., vol. 17, 1922, pp. 233-259. W. E. P ratt : Oil and gas in the Texas Panhandle. Bull. Am. Assoc. Petroleum Geologists, vol. 7, 1923, pp. 237-246. C. M. Bauer : Oil and gas fields of the Texas Panhandle. Idem, vol. 10, 1926, pp. 733-746. C. N. Gould and F. E. Lewis : The Permian of western Oklahoma and the Panhandle of Texas. Okla. Geol. Survey Circular 13, 1926. 35 Sidney Powers : Bull. Am. Assoc. Petroleum Geologists, vol. 10, 1926, flg. 1, p. 2. (The southeastern extension of the Arbuckle Mountains shown is incorrect.)

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The distance from the New Mexico line west of the buried Amarillo Mountains to Port Sill, at the east end of the present Wichita Mountains, is 250 miles, and the’ distance from Port Sill to the Criner Hills is 80 miles. The Wichita Mountain system is a long range composed of many echelon axes. Evidence of several short breaks in it has been found. The Wichita Mountains and the Red River uplift in Wilbarger County are about 50 miles apart, and the north and south flanks of the former Wichita Mountains between Healdton and Muenster are about 35 miles apart. Granite and other igneous rocks form the Amarillo buried ridge and Wichita Mountains, and the outcrops of the Ordovician limestone are practically confined to the north flank of the latter, between Gotebo and Fort Sill, where they form ridges that are separated from the granite hills. The limestone is as thick as it is in the Arbuckle Mountains. No younger rocks crop out through the Permian mantle. The Permian beds found in drilling thicken so rapidly north of the Wichita Mountains, in the Anadarko trough, that they measure over 4,500 feet near Canute) 25 miles from the nearest granite outcrop. CRINER HILLS. The Criner Hills, a part of the Wichita Mountain system, is a com­ plexly faulted horst consisting largely of Ordovician limestones like those in the Arbuckle Mountains, which projects through Pennsylvanian rocks 5 miles southwest of Ardmore and 15 miles south of the south flank of the Arbuckle Mountains.36 Buried hills of similar rocks occur en échelon from the Criner Hills to Fort Sill, at the east end of the present Wichita Mountains, a distance of 80 miles, and from there on the surface past Gotebo, a distance of 40 miles. Among the best known of these hills are Hewitt, Healdton, Loco, Woolsey (township 2 south, range (i west) and Nellie (township 1 north, range 9 west).37

86 Sidney Powers : Crinerville oil field, Carter County, Oklahoma. Bull. Am. Assoc. Petroleum Geologists, vol. 11, 1927, pp. 1067-1085. 87 Frank Gouin : The geology of the oil and gas fields of Stephens County, Okla. Oklahoma Geol. Survey Bull. 40E, 1926. C. W. Tomlinson : The geology of the oil and gas fields of Carter County, Okla. Idem, Bull. 40H, 1927. R. C. Moore : The relation of mountain folding to the oil and gas fields of southern Oklahoma. Bull. Am. Assoc. Petroleum Geologists, vol. 5, 1921, pp. 33-48. J. V. Howell : Some structural factors in the accumulation of oil in southwestern Oklahoma. Econ. Geol., vol. 17, 1922, pp. 15-33. C. W. Tomlinson : Pennsylvanian system in the Ardmore Basin. Bull. Geol. Soc. Am., vol. 38, 1927 (abstract). Ordovician rocks under Healdton have been described by Sidney Powers (The Healdton field, Oklahoma, Econ. Geol., vol. 12, 1917, pp. 594-606), by J. C. Bartram and Louis Roark (The Healdton field, Oklahoma, Am. Assoc, of Petroleum Geologists Bull., vol. 5, 1921, pp. 469-474), by J. W. Merritt (Pennsylvanian sedimentation around Healdton Island, idem., vol. 4, 1924, pp. 47-§2). Ordovician rocks under Hewitt have been described by G. E. Burton (The Hewitt oil field, Structure of Typical American Oil Felds, Am. Assoc, of Petroleum Geologists, vol. 2, 1929).

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Although the southeastern end of this line of limestone ridges is close to the Arbuckle Mountains, there is an intervening deep trough of Pennsylvanian sediments in which no well has penetrated older rocks. This trongh extends southeastward, and the Preston anticline, north of Denison, Texas, is in its center. The trough includes other similar anti­ clines,38 in which the type of folding is very different from that over the buried hills. Conclusions regarding the geological history of this line of hills, which are considered the north rim of the original Wichita Mountains and an extension of the present rim between Gotebo and Fort Sill, must be reached by a study of sections adjacent to the Criner Hills. The Criner Hills (figure 6) were formerly buried, but their eastern and larger part was uplifted relative to the adjacent part on the west and has been uncovered by erosion. The western part was found by drilling in the Crinerville oil field to depths of 1,000 to more than 2,500 feet. An eroded Ordovician surface slopes westward unconformably be­ low the upper Glenn.39 On the east side of the hills the Caney shale has not been found, and it may be missing because of uplift. The uplift on the west side, believed to have been the Wichita Mountains, is recorded on the east side in coarse conglomerates near the base of the Glenn forma­ tion. The Criner Hills and the entire Wichita area are believed to have been folded and faulted at that time as they appear today, but they were subject to later faulting, warping, and erosion. Beds of conglomerate and sandstone are found throughout the upper part of the Glenn, which is 9,300 feet thick, and in the lower part of the overlying Hoxbar, 4,000 feet of which is exposed. Conglomerate is not found in the part of the Pennsylvanian basin north of Ardmore or on the south flank of the Arbuckle Mountains, but the time breaks are recorded by the fossils. The oldest Pennsylvanian rocks on the west side of the Criner Hills belong to the middle or upper Glenn, which is overlain by the Hoxbar. Farther west the Hoxbar appears to merge into non-marine or shallow water beds and to be overlain by the youngest parts of the Cisco, forma­

88 W. L. Goldston, Jr.: Differentiation and structure of the Glenn formation. Bull. Am. Assoc. Petroleum Geologists, vol. 6, 1922, pp. 5-23. C. W. Tomlinson : Op. cit. F. M. B ullard: Geology of Love County, Oklahoma. Oklahoma Geol. Survey Bull. 33. 1925. P. M. Bullard : Geology of Marshall County, Oklahoma? Idem, Bull. 39, 1926. Also U. S. Geol. Survey Bull. 736a, 1922. 39 The interpretation of the stratigraphy of the Ardmore Basin has been revised by Girty and Roundy. (Notes on the Glenn formation of Oklahoma, Bull. Am. Assoc. Petroleum Geologists, vol. 7, 1923, pp. 331-349), who include the Springer member of the Glenn in the Caney (H. D. Miser in Okla. Geol. Survey Bull. 35, 1925, p. 26, foot­ note), and by Tomlinson, who replaced the Cup Coral member by the Domick Hills member.

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tion, which are red beds at the east and alternating “red” and “blue” shale farther west, as recorded in well logs. Between the Healdton, Hewitt, and Criner Hills on the south and the Arbuckle Mountains on the north, most of the rocks exposed at the surface belong to the steeply folded Glenn formation, which is overlain unconformably by the Pontotoc conglomerate and Permian “Red Beds.” Folding occurred at the time of the last and greatest movement in the Arbuckle Mountains and Wichita Mountains, late in Pennsylvanian time, when considerable shortening of the mountain area and intervening basin took place. Some of the oil fields of southern Oklahoma have been discovered be­ neath the Permian mantle by drilling on anticlinal folds in the Permian beds, but no trace of such folds can be found above other fields. The superposition of structure in the Permian above the Pennsylvanian is poor. "RED BED” 8TNCLINE WEST OF THE CRINER HILLS A deep trough corresponding to that north of the Healdton and the Hewitt buried hills may lie between these hills and Red River. Deep drilling has shown that this trough contains over 4,700 feet of Permian and Pennsylvanian beds, but no well has reached the pre-Pennsylvanian rocks. A study of macrofaunas and microfaunas shows that the oldest Pennsylvanian formation is middle or upper Glenn, equivalent to the upper Strawn and Canyon in Texas and to the Boggy-Wewoka north of the Arbuckle Mountains. The writer believes that the Glenn rests directly on the Ordovician. Cuttings from wells in the Hambro field, in township 6 south, range 5 west, show upper Glenn microfossils and a conglomerate of crinoid stems (which forms the most productive oil sand), probably of upper Glenn age, resting on Ordovician limestone. A few miles south, in the Oscar gas field, the upper Glenn is underlain by pre-Cambrian granite. The same condition exists south of Red River, in the Nocona field and elsewhere. The Duncan field is underlain by Glenn sediments40 and Ordovician beds were found in the northeast 14 northeast %, section 32, at 3,548 feet.

40 Girty and Roundy have reported fossils from the following localities: E. H. Jones, trustee, Springer No. 3, SE. cor. NW. %, sec. 28, T. 1 S., R. 8 W., South Duncan field; depth, 2,368 feet: Cisco (letter dated August 7, 1922, to Frank Gouin). Twin State Oil Company’s Bridenthall No. 2, SW. cor. SE. Vi, sec. 19, T. 1 S., R. 8 W .; depth, 2,408 fe e t: Cisco ahove basal Cisco (letter dated May 3, 1922, to Willis Storm ). j ; C. Keys, Ellis No. 1, NE cor. sec. 27, T. 1 S., R. 10 W., Walters gas field; depth, 2,210 feet; age,. undetermined (letter dated April 23, 1920, to J. V. Howell). Na­ tional Oil and Development Company, Bullard No. 1, SW. cor., NE. %, SW. M, sec.

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The Loco field is underlain by Pennsylvanian of upper Canyon or Cisco age41 and by Ordovician at 1,556 feet.42 RED RIVER-QAINE8VILLE UPLIFT An uplift in Texas that lies beneath Permian, Pennsylvanian, and Cretaceous beds extends from Foard County, near the west line of Wil­ barger County, eastward beyond the east line of Cooke County, Texas. Future drilling may reveal the full extent of this uplift and may also show that many hills are superposed on it in addition to those already found. The uplift is not as simple as that which forms the echelon hills between the Criner Hills and Gotebo, but includes several more or less parallel lines of such hills. Moreover, granite has been found under the Pennsylvanian rocks in several anticlines (as at South Vernon,43 Oscar,44 Nocona,45 Thalia,46 and Sanger47 instead of the usual Ordovician limestone (as in Wilbarger and northern Wichita and Clay counties48 and at Petrolia,49 Hambro,50 Waurika,51 and in the Bulcher-Muenster ridge 52).

22, T. 2 S., R. 11 W .; depth, 2,000 feet: Pennsylvanian (letter undated). Elmhurst Development Company, sec. 3, T. 1 N., R. 24 W .; depth, 2,780 to 2,994 fe e t: Pennsyl­ vanian (letter dated July 29, 1920, to J. V. Howell). J. C. Keys, Grose No. 5, center of east line, NW. %, NW. . sec. 26, T. 1 S., R. 10 W., W alters gas field; depth, 2,152 feet: Permian? (same letter). J. C. Keys, Grose No. 1, same lease; depth, 2,200 feet: “more probably Permian than Pennsylvanian,” non-marine facies (letter dated February 21, 1921, to J. V. Howell). D. K. Gregor reported fossils of Oread age (Douglas formation, upper Pennsylvanian), in Keys Petroleum Company, Moyer No. 1, SE. Yi sec. 21, T. 1 S., R. 1 W„ below 1,800 feet. ',L Owl City Company, Ida BiUy No. 9, center of sec. 9, T. 3 S., R. 5 W .; depth, 871 to 880 feet; determination by G. H. Girty and P. V. Roundy, letter to the writer dated February 2, 1922. C. H. W egemann: Loco gas field, Oklahoma, U. S. Geol. Survey Bull. 621c, 1915. Sidney Pow ers: Age of the oil in southern Oklahoma fields. Trans. Am. Inst. Min. Engrs, vol. 59, 1918, pp. 554-579. 42 Owl Oil Company, Mary Wilson No. 6, NW. % sec. 9, T. 3 S., R. 5 W. 43 Barclay & Meadows, Stevens No. 14, SB. % NW. %, NE. %, sec. 83 ; black igneous rock at depths of 2,970 to 3,007 feet; Texas Company Zipperle No. 1, south line of SE. % sec. 24; gneiss (?) a t depths of 2,881 to 2,935 feet. 44 Pink granite at depth of about 1,900 fe e t; also granite gneiss (Econ. Geol., vol. 17, 1922, p. 248, footnote). 45 Pink granite and gneiss in a number of wells at depths of 1,840 to 2,500 feet. 49 Depth, 2,175 feet (Roxana and Fain-McGaha, Matthews No. 1, 2 miles north of Thalia, Foard County). 47 Depth, 1,870 feet, Kelsey, Jenkins, et al., Wade No. 1, Carpenter Survey, Denton County. 48 Magnolia Oil Company and Texhoma Oil Company Beach No. 1 ; C. T. R. R. Survey 443, 3 miles south of Burkburnett oil field; Ordovician (?) limestone at depths of 1,500 to 2,995 feet; black igneous rock (gneiss?) at depths of 2,995 to 3,501 feet. Many other wells have reached Ordovician limestone, but the first limestone in most places is supposed to be of Canyon age. In Wilbarger County, west of the Electra oil field, the Texas Company’s Waggoner No. 129 found Ordovician limestone at 3,020 feet. ®U. S. Geol. Survey Bull. 726, 1922, p. 293. 60 Idem. 51 Several Ordovician hills have been reported west and southwest of Waurika, but microfossils indicate that the limestone is of Pennsylvanian age. 62 Depth, 1,400 to 2,100 feet.

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This uplift is known for a length of about 100 miles, and the indica­ tions are that its width is from 15 to 20 miles where there are echelon ridges. Its northern edge, near Gainesville and Waurika, is about 30 miles from the line of buried hills between the Criner Hills and Fort Sill. ‘ Connection between the Criner Hills and Gainesville and be­ tween the buried hills near Waurika and the Ordovician limestone west of Lawton has not yet been found. The Eed River arch, as it is known in northern Wichita County, Texas, there diverges from its general northwesterly trend and extends due west. On the Ordovician lie Pennsylvanian sediments belonging to the upper Canyon and Cisco formations (upper Deese, Hoxbar, and younger beds), which are overlain by Permian sediments west of the center of Clay County. The base of the Cisco formation is supposed to be one of the conglomerates that crop out north of Bonita and that are found at a depth of about 600 feet in the Nocona field. Microfossils from a well at Muenster have been identified by B. H. Harlton as upper Glenn. In northern Wichita County the Permian is believed to be only a few hundred feet thick, and the oil-sand series is Cisco.53 Limestones that lie below the oil sands and above the Ordovician are correlated on litho- logic grounds with the Canyon. Correlation with the Oklahoma section is unsatisfactory, and Tomlinson has pointed'out, as stated above, that the base of the Permian in Texas is about 1,000 feet stratigraphically above its base in Oklahoma.54 For the purpose of this paper the most important fact to be considered is that no Pennsylvanian sediments below the upper Glenn (lower Canyon, or possibly uppermost Strawn) have been found on the Red River uplift or between there and the north rim of the Wichita Moun­ tains. The Strawn formation extends from the Llano-Burnet uplift northward to Wichita and Clay counties, where it is overlapped uncon- formably by the Canyon. The Red River uplift is therefore believed to be a part of the Wichita Mountain system and to have been folded in lower Strawn and lower Glenn time. It was refolded and reuplifted several times, the strongest folding of the Pennsylvanian rocks evidently occurring late in Cisco time, because the folds in the superposed Per­

53 L. C. Glenn: Some paleontological evidence on the edge of the oil-hearing horizon a t Burkburnett, Texas. Bull. Am. Assoc. Petroleum Geologist, vol. 5, 1921, pp. 154-8. Describes Cisco fossils from the well of the Hamilton Oil Association, in sec. 13, T. 5 S., E. 15 W., Tillman Co., Okla. (north shore of Eed Eiver), a t a depth 1,581-6 feet. :,i C. W. Tomlinson: Pennsylvanian system in the Ardmore Basin. Bull. Geol. Soc. Am., vol. 38, 1927. Powers thinks this discrepancy is due to overlap of the Permian south of Eed Eiver. Permian fossils are described in U. S. Geol. Survey Bull. 621, 1916, pp. 19, 35, 45; and in Bull. 602, 1915, p. 25; also by G. D. Morgan, Bureau of Geol. Bull. 2, 1924, p. 136.

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mian strata are not so steep as those in the upper Glenn formation oil sands at Healdton and Hewitt. The last folding occurred during or after Permian deposition. The subsequent movements appear to have been gentle warpings.

GEOLOGIC HISTORY AND GEOGRAPHIC EXTENT The geologic history of the relics of the Wichita Mountains that project through the Permian plains is obscure because no post-Viola limestone (late Ordovician) or pre-Permian rocks are exposed at the surface.55 Upper Glenn and younger Pennsylvanian rocks are found on the buried flank of the Wichitas, as stated above. Drilling has proved that the Wichita Mountains extend continuously past the buried Amarillo Mountains into New Mexico. Beds of Ordo­ vician limestone flank the mountains on the north as far west as Gotebo and continue underground in a northerly course into Kansas west of Harper County. The limestone is found underground south of the mountains and it feathers out westward underground in a general southwesterly direction. Whether or not the limestone was originally deposited farther west is not known. The absence of Silurian, Devonian, and Mississippian formations from the main Wichita Mountains sugge'sts pre-Pennsylvanian folding and probably regional uplift on the west. Successively younger Per­ mian formations appear on the west, but the drill records show no rocks older than upper Cisco above the granite as far west as eastern New Mexico. The subsurface geology indicates late Pennsylvanian and early Per­ mian folding and basin downwarping (seen in the Anadarko and west Texas troughs) interrupted locally by Permian folding and faulting and followed by gentle folding and broad upwarping after Permian and after Triassic sedimentation. Regional tilting after Lower Cretaceous time raised the High Plains to their present elevation, so that the regional eastward dip is practically the same as the regional eastward topographic slope. T h e L l a n o -B u r n e t U p l if t

The Llano-Burnet, or Central Mineral region, is 200 miles south of the Red River line of folding and about 270 miles south-southwest of the Arbuckle Mountains. It is 80 miles long from east to west and 65 miles

55 J. V. H ow ell: Op. cit. J. A. T aff: Preliminary report on the geology of the Arbuckle Mountains in Indian Territory and Oklahoma. U. S. Geol. Survey Prof. Paper 31, 1904. Frank Gouin : Geology of Beckham County, Okla. Geol. Survey Bull. 40m, 1927.

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wide from north to south, and is composed of pre-Cambrian igneous and metamorphic rocks surrounded by Cambrian and Ordovician limestones, and it has some sandstones at and near its base.56 The upper limestone of this series, the Ellenburger, closely resembles the Arbuckle limestone of‘the same age, in Oklahoma (figure 7). Cheney has recently found Silurian fossils in the South Bend oil field, southern Young County, depth about 4,200 feet, which Ulrich says suggest “Ferndale, Richmond plus St. Clair.”57 Therefore it is evident that at least part of the Hunton limestone of Oklahoma, or its equivalent, was originally deposited in cen­ tral Texas, and that most of it was removed during the same erosion period which truncated the Hunton limestone in Oklahoma. An outer rim of late Mississippian and early Pennsylvanian beds, Bend series (figure 8), is found north of the older rocks and outliers of the same series occur in the central mass. These beds rest uncon- formably on the older rocks. Limestone of Boone age, at the base, is overlain disconformably by the Barnett shale, which is of the same age as the Fayetteville shale of Oklahoma.58 Overlying and overlapping these Mississippian formations are the Marble Falls limestone and the Smith- wick shale, which are of the same age as the Wapanucka limestone of Oklahoma. Farther north, beneath the basin of younger rocks, the litho- logic characteristics of these formations change.59 Unconformably overlying the older rocks is the central Texas section of the Pennsylvanian, at the base of which lies the Strawn formation (figure 9), equivalent to the Olenn formation, which is overlain by the Canyon and Cisco groups. The Strawn is composed of material derived from the east and it thickens northward, away from the Llano-Bumet uplift.

58 Sidney Paige: Llano-Bumet, Texas. Geologic atlas of the United States. U. S. Geol. Surrey, Folio 183, 1912. J. A. Udden and others: Review of the geology of Texas. Univ. of Texas Bull. 44, revised ed., 1919. 67 M. G. Cheney: Pre-Mississippian production in Texas. The Oil and Gas Journal, April 12, 1928, p. 31. 58 P. V. Roundy, G. H. Girty, and M. I. Goldman : Mississippian formations of San Saba County, Texas. U. S. Geol. Survey Prof. Paper 146. M. I. Goldman: Lithologic subsurface correlation on the “Bend Seriep” of north-central Texas. U. S. Geol. Survey Prof. Paper 129a, 1922. F. B. Plummer and R. C. Moore: Stratigraphy of the Penn­ sylvanian formations of north-central Texas. Univ. of Texas Bull. 2132, 1921. G. H. Girty: The Bend formation and its correlation. Bull. Am. Assoc. Petroleum Geologists, vol. 3, 1919, pp. 71-81. F. B. Plum m er: Preliminary paper on the stratigraphy of the Pennsylvanian formations of north-central Texas. Idem, pp. 132-145. R. C. Moore : The Bend series of central Texas. Idem, pp. 213-237. G. H. Girty and R. C. Moore: Age of the Bend series. Idem, pp. 418-420. According to micropaleontologlcal determination by B. H. Harlton, the series is of Fayetteville age. 59 M. I. Goldman : Op. cit. Frank Reeves: Geology of the Ranger oil field, Texas. U. S. Geol. Survey Bull. 736e, 1923. John A. Udden: Subsurface geology of the oil districts of north-central Texas. Bull. Am. Assoc. Petroleum Geologists, vol. 3, 1919, pp. 34-38. LXIX— B ull. Geol. Soc. Am., Vol. 39, 1927

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1064 S. POWERS--- AGE OF FOLDING OF OKLAHOMA MOUNTAINS 1 The Llano-Burnet area adjoins Llanoris. Wells drilled southwest, southeast, east, and northeast of the outcrops 'of pre-Cambrian rocks have found pre-Cambrian schists beneath the Cretaceous. The eastern edge of the Pennsylvanian is covered by the Cretaceous overlap and possi­ ble extensions far toward the east cannot be determined because the Balcones and Mexia fault zones, which have been caused by a regional depression of the Coastal Plain on the south and east, have dropped the older rocks out of the reach of the drill. These fault zones follow a line of outcrop which may also be an ancient hinge line60 between the Penn­ sylvanian and older rocks, because the latter have been found in a smoothly curved line along and south of the fault zones from Waco to San Antonio; thence westward past Del Eio and Sanderson, and from the southwestern part of Terrell County southward into Mexico, where outcrops of these rocks occur. A northward extension of the Llano-Burnet uplift, the Bend arch,61 runs for more than 120 miles toward Eed River and corresponds roughly to the northward extension of the Arbuckle Mountains toward Seminole. Deformation in Paleozoic time began after the Silurian (Hunton?) was deposited. After the deposition of the Barnett shale and Bend series (Marble Falls and Smith wick) there was a pronounced uplift of the entire region, including Llanoris, and at this time the area now on the east side of the Bend arch was warped downward, so that it was covered by basal Strawn. The Red River uplift occurred at the same time or a little earlier, as recorded in the conglomerates of the lower part of the Glenn formation on the east side of the Criner Hills. The northeast part of the present Arbuckle Mountains was uplifted at about the same time as the Llano-Burnet region (figure 9).

60 Johan A. Udden : Trans. Am. Inst. Min. Engrs., vol. 57, 1918, p. 1086. Udden refers to the Balcones fault zone and to the underlying igneous and metamorphic rocks as . . an axis of an ancient series of rocks, . . . a line of disturbance which certainly must be very old.” 81W. F. Cummins: Geol. Survey of Texag, F irst Ann. Rept., 1889, p. 147; Second Ann. Rept., 1890, p. 364. E. T. Dumble: The occurrences of petroleum in eastern Mexico as contrasted with those in Texas and Louisiana (“following deposition [of the Bend series] an uplift occurred, forming the Lampasas geanticlinal, which runs north­ eastward from the old Paleozoic land area of the Llano region toward Red River”). Trans. Am. Inst. Min. Engrs., vol. 52, 1916, p. 250. M. G. Cheney: The economic importance of the Bend series as a source of petroleum supply. Oil Trade Journal, April, May, 1918. R. T. Hill. Ibid., June, 1918. Dorsey Hager : Geology of the oil fields of north-central Texas. Am. Inst. Min. Engrs., Bull. 138, 1918, pp. 1109-1118. W. E. P r a tt: Am. Inst. Min. Engrs., Bull 140, 1918, p. 1155; also, Geologic structures and producing areas in north Texas petroleum fields. Bull. Am. Assoc. Petroleum Geologists, vol. 3, 1919, pp. 44-70. William Kennedy : Southwestern Oil Jour., January 4, 1919. E. H. Sellards: The underground position of the Ellenburger formation in north-cen- tral Texas. Bull. Am. Assoc. Petroleum Geologists, vol. 4, 1920, pp. 283-298, repub­ lished as University of Texas Bull. 1849, 1920. M. G. Cheney: Op. cit.

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Strawn sandstone and shale were deposited between the Red River and Llano-Burnet uplifts, the upper beds of the Strawn covering part of the Red River uplifted beds and probably part of those of the Llano- Burnet. The Canyon and Cisco beds are locally unconformable with those of the Strawn and with each other. On the west side of the Llano- Burnet uplift in some other localities the Canyon overlaps the Strawn and the Cisco overlaps all the older formations. Conglomerates in the Strawn formation and near the middle and top of the Cisco, composed largely of chert pebbles, were derived from areas on the east or northeast, because they can be traced for long dis­ tances along the north-south strike of these formations. During part of Strawn time the Wichita Mountains were a land area and the Woodford chert was a source of conglomerate pebbles. In Cisco time the Woodford was being eroded in the Arbuckle Mountains and granite, sandstone, and limestone were being eroded from the central core of the Wichita Moun­ tains. The western limit of the chert formations that crop out in the Ouachita Mountains or of their possible extension in Llanoris in Cisco time is not known. The cherts of the Ouachitas were exposed over a rather small area in Oklahoma and the chert lentils of the Atoka forma­ tion are local. Some deformation, which is shown in surface outcrops, accompanied Pennsylvanian sedimentation. Local buried hills are reflected in the overlying sediments62 and folds in the Strawn and Canyon formations fade out upward and even disappear in the Cisco formation. The Bend arch was formed by the downwarping of the western flank after lower Strawn sedimentation.63 There is no stratigraphic break at the surface between the Pennsylvanian and Permian or between Permian formations, but folding and faulting were probably in progress. Drilling in the west Texas basin, however, has shown that the “Big Lime” (Word forma­ tion?) was faulted and gently folded before the deposition of the over- lying anhydrite series.64 After the Permian strata were uplifted and eroded there were other movements, whose intensity varied from region to region. The down- warp of Llanoris on the south and east in Cretaceous time and the frac­ turing of the Coastal Plain sector in successive belts from the Balcones

02 Sidney Powers: Structural geology of the Mid-Continent region, a field for re­ search. Bull. Geol. Soc. Am., vol. 36, 1925, pp. 379-392. 63 M. G. Cheney, of Coleman, Texas, advanced this idea of the formation of the Bend arch at the meeting of the American Association of Petroleum Geologists in 1927. 64 Sidney Powers : Buried ridges in West Texas. Bull. Am. Assoc. Petroleum Geolo- gists, vol. 11, 1927, pp. 1109-1115.

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fault zone to the edge of the Gulf of Mexico, as loading and subsidence continued, were the most important later movements.

T h e M a r a t h o n U p l if t

The Marathon uplift is 200 miles west of the Llano-Burnet region, is 20 miles west of the western edge of Llanoris as now known from wells, and is close to the Front Range of the Cordillera. The Glass Moun­ tains bound the Marathon uplift on the northwest. Reference is made to this distant Marathon uplift because a “window” of Paleozoic rocks there exposed affords evidence of folding contemporaneous with Appa­ lachian folding65 (figure 5). Still another “window” is the "Solitario uplift, 50 miles southwest of the Marathon.66 Others may exist in Mexico, all fringing Llanoris on the north and northwest. Upper Cambrian sandstone is overlain unconformably by Ordovician chert and limestone, and these are overlain unconformably by the Caballos novaculite, of Devonian (?) age, which is correlated with the Arkansas novaculite of the Ouachitas. Above another unconformity there are shales of the Tesnus forma­ tion, of Pennsylvanian age. David White assigns the Tesnus flora to Pottsville, probably early Strawn time,67 and B. H. Harlton finds the Tesnus microfossils in the Caney shale of Oklahoma. According to Harlton, the Tesnus is younger than the Barnett shale and older than the Marble Falls. The Dimple formation, consisting of limestone, black chert, and black shale, overlies the Tesnus conformably and contains the microfauna found in the Marble Falls of Texas and the Wapanucka of Oklahoma. The shale and sandstone of the Haymond formation over­ lie the Dimple, but they have not yielded fossils. Above these lower Pennsylvanian rocks and separated from them by an unconformity, there are the Gaptank formation, of Pennsylvanian age; the Wolf camp formation, of lower Permian age; and, in the Glass Mountains, a series of limestones of Permian age capped by the Bissett formation, which contains Permian fossils.68

65 C. L. Baker and W. F. Bowman : Geologic exploration of the southeastern Front Range of Trans-Pecos, Texas. Univ. Texas Bull. 1753, 1917, pp. 61-77. J. A. Udden: Notes on the geology of the Glass Mountains. Idem, pp. 1-59. 66 Sidney Powers: Solitario uplift, Presidio-Brewster counties, Texas. Bull. Geol. Soc. Am., vol. 32, 1921, pp. 417-428. 67 Letter to the writer in 1919, cited by McCoy in Bull. Am.Assoc. Petroleum Geolo­ gists, vol. 5, 1921, p. 545. Pow ers: Loc. cit. 68 Philip B. King and Robert E. King hare published a revision of the geology of this region in Bulletin 2801 of the Bureau of Economic Geology, Austin, Texas. See also P. B. King: The geologic structure of a portion of the Glass Mountains of west Texas. Bull. Am. Assoc. Petroleum Geologists, vol. 10, 1926, pp. 877-884. The Bissett

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Tlie Gaptank formation consists of conglomerate and alternating beds of limestone, sandstone, and shale at its base, shale and interbedded limestone in its middle part, and limestone with interbedded shale in its upper part. Sehuchert, Keyte, and others correlate the lower Gap­ tank with the Canyon and the Upper Gaptank with the lower Cisco. Mierofossils confirm this correlation. Mountain-building that formed the Caballos Mountains of Schuchert followed Gaptank sedimentation. The Wolf camp formation lies unconformably, at diSerent places, on most of the older formations. At some places it has a thick series of conglomerates at the base; at others it can not be distinguished with certainty from the Gaptank. Its age is in question. The “Uddenites zone” of the Wolfcamp is placed in the Gaptank by Keyte and others and is correlated with the Cisco, but it is placed in the Wolfcamp and regarded as of Permian age by Schuchert and Böse.69 Harlton finds Pennsylvanian (Cisco) microfossils in the basal Wolfcamp; but here again the position of the Gaptank-Wolf camp boundary is unknown. The Wolfcamp is correlated by Keyte and others with the Cibolo formation at Shafter, Texas. Another unconformity separates the Wolfcamp from the Hess. The Hess, Leonard, Ward, Yidrio, Gilliam, and Tessey of the Glass Moun­ tains are structurally conformable and are overlain unconformably by the Bissett conglomerate. Schuchert points out that the Permian seas came in from the northwest, and that the Leonard and Word are the most widespread Permian formations. After their deposition, in middle or late Permian time, the sea “became more circumscribed and highly saline.” 70 Correlation of the mountain-building movements at or before the end of Mississippian time and during and at the end of Pennsylvanian time with the geologic history of the Llano-Burnet area and of the mountains of southern Oklahoma indicates that the Marathon uplift is included in the Oklahoma Mountains. The axes of folding trend from northeast to southwest. The axis of the Permian folding of the Glass Mountains

formation. Am. Jour. Sei., 5th ser., vol. 14, 1927, pp. 212-221. I. A. Keyte, W. A. Blanchard, and H. L. Baldwin: Gaptank-Wolfcamp problem of the Glass Mountains, Texas. Jour. Paleontology, vol. 1, 1927, pp. 175-8. Charles Schuchert: The Pennsyl- vanian-Permian systems of western Texas. Am. Jour. Sei., 5th ser., vol. 14, 1927, pp. 381-401. C. N. Gould and Robin Willis: Tentative correlation of the Permian forma­ tions of the southern Great Plains. Bull. Geol. Soc. Am., vol. 38, 1927, pp. 431-442. Johan A. Udden : Fossils from the Word formation of west Texas. Bull. Geol. Soc. Am., vol. 38, 1927, p. 159, finds th at the Word and Delaware Mountain formations contain the same fossils. C. L. Baker, Bull. Am. Assoc. Petroleum Geologists, vol. 11, 1928, pp. 1111-1116. w E. Böse : Bureau of Econ. Geol., Univ. of Texas Bulls. 55, 1916, and 1762, 1919. Op. cit., p. 393.

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ran from northeast to southwest because of a rejuvenation of the Mara­ thon uplift, but it is not connected with the Oklahoma Mountains. The folds of the Delaware Mountains and other Cordilleran mountain ranges, including the buried folds and fault-blocks, trend north-northwest, at right angles to the earlier folds, in the same direction as the folds of the much younger Cordillera. Another rejuvenation of the Marathon uplift and of the uplift of flanking Glass Mountains accompanied the Laramide revolution. This movement produced dips of as much as 5 degrees in the Cretaceous strata surrounding the older rocks and uncov­ ered buried hills (Baraboo inliers), such as Sierra Madera. The Solitario uplift, 50 miles southwest of the Marathon uplift and 9 miles from the Rio Grande, is a circular unroofed dome of Cretaceous limestone in which Paleozoic rocks are exposed—a miniature Marathon- Glass Mountains area, similar- both in its inclosing unroofed Cretaceous dome and in the arrangement of its Paleozoic rocks. In this uplift steep northeast-southwest folds of Caballos novaculite are underlain by the limestone and shale of the Marathon formation and overlain by the shale of the Tesnus formation. The Permian limestone is confined to its northwest part. Other Pennsylvanian inliers in this area that lie farther west, at Shafter and at Pinto Canyon,71 were affected by Permian folding. The Ouachita Mountains, Llano-Burnet uplift, Marathon uplift, and Solitario uplift are peripheral to Llanoris and are within 50 miles of schist struck by wells. Pennsylvanian rocks are found in these moun­ tain structures and on their sides toward Llanoris, but Permian rocks are found only on the opposite side. This edge of Llanoris was a Per­ mian as well as a Pennsylvanian shoreline and was afterward the hinge line of the Gulf Coast embayment, and as such became greatly fractured.

T h e A n c e s t r a l R o c k y M o u n t a in s

Interpretations of Willis T. Lee’s Ancestral Rocky Mountains72 have moved both in geography and in time. It is generally agreed that the beds of Pennsylvanian age were deposited on an uneven granitic base­ ment, and that the Ancestral Mountain uplift commenced in Pennsyl­

n Charles Laurence Baker: Univ. of Texas Bull. 2745, 1927 (1928), p. 10. 12 W. T. Lee: General stratlgraphlc break between Pennsylvanian and Permian in western America (abstract), Bulletin Geol. Soc. Am., vol. 28, 1917, pp. 169-170. Early Mesozoic physiography of the southern Rocky Mountains. Smithsonian Misc. Coll., vol. 69, No. 4, 1918. Concerning granite In wells in eastern New Mexico. Bull. Am. Assoc. Petroleum Geologist, vol. 5, 1921, pp. 163-167; discussion, pp. 329-330. Charles Schuchert: Textbook of Geology, pt. 2, 1924, p. 425 (map). N. H. Darton : Geologic structure of parts of New Mexico. U. S. Geol. Survey Bull. 726e, 1922, p. 202.

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vanian time. The Pedernal Hills (figure 11), near Vaughn, New Mexico, may have been formed by this uplift, because the Yeso forma­ tion rests on pre-Cambrian rocks.73 It is believed that the Glass Mountains and the north-northwest-trending faults near the oil fields in the west Texas Permian basin, which were developed during Permian (post- Word) time, and the folds of the oil fields should be included in the An­ cestral Rockies. Contemporaneous faulting and probably folding are known in the buried Amarillo Mountains (figure' 6), but the direction of the folding is different from that in west Texas and agrees with that of the folding in the Oklahoma Mountains. The Ancestral Rockies there­ fore appear to be the true ancestors of the present Rocky Mountains, and the resultant of a different set of forces from that which folded the Okla­ homa Mountains.

S u m m a r y

The Oklahoma Mountain system extends through Arkansas, Okla­ homa, and Texas, curving from west in Arkansas to northwest in cen­ tral Texas, to southwest in western Texas. There is a marked change in the direction of the axis of folding in western Texas from the north­ ern to the southern part of the State. The Ozark Mountains resemble the Cincinnati and Nashville arches. Llanoris, or at least the southern part of Llanoris, has the same position with respect to the Oklahoma Mountains as Appalachis with respect to the Appalachian Mountains. The Arbuckle and Wichita Mountains and the Llano-Burnet and Marathon uplifts are folded parts of the Oklahoma system. The Ouachitas Mountains are composed at their west end of overthrust sheets that resemble in general the overthrust parts of the southern Appa­ lachians. Early Paleozoic seas in which limestone was deposited extended from a point east of the Ozark Mountains southwestward past the Marathon uplift. Southeastern arms of these seas, or separate seas, in which shale and sandstone were deposited, occupied an area between the Arbuckle Sea and Llanoris. This shale and sandstone represents the Ouachita Mountain section. Periodic oscillations of land and sea continued through Paleozoic time,

m Personal communication from E. Russell Lloyd. J. L. Rich: A probable buried mountain range of early Permian age east of the present Rocky Mountains in New Mexico and Colorado. Bull. Am. Assoc. Petroleum Geologists, vol. 5, 1921, pp. 605- 608. P. A. M elton: The ancestral Rocky Mountains of Colorado and New Mexico. Jour. Geol., vol. 33, 1925, pp. 84-89. Buried granite hills at Picacho (sec. 21, T. 11 S., R. 18 E.), Anton Chico (sec. 30, T. 11 N., R. 19 E .), and Santa Rosa (sec. 5, T. 8 N., R. 23 E.) belong to the Ancestral Rockies, as proved by arkoses in near-by wells that did not reach granite (as in sec. 14, T. 15 S., R. 17 E.) and elsewhere.

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and the most complete sections of the deposits then laid down are found in the Arbuckle and Ouachita Mountains. The amount of pre-Penn­ sylvanian deformation in the Wichita Mountains is unknown, because the main granite core of the mountains is overlapped by sediments de­ posited after early Pennsylvanian folding. There is a marked discord­ ance between the early Ordovician and the Mississippian formations in the Llano-Burnet uplift, and this Devonian (?) uplift is believed to have affected all southern Llanoris. The axes of folding in the Marathon uplift were probably determined by the same Devonian orogenic move­ ments. Broad anticlines and synclines in the Arbuckle area were formed at the end of Hunton (Devonian) time. An additional uplifted, mountain-built area is postulated to account for the limestone boulders in the Caney shale of the Ouachita Moun­ tains—a pre-Ouachita uplift now concealed beneath the overthrust beds in these mountains. Beginning early in Mississippian time, folding and erosion progressed with sufficient rapidity to expose the Arbuckle lime­ stone by Caney time, and the boulders in the Ouachita Mountains in the Caney and the Wapanucka formation were derived from the uplifted area. The Atoka formation is supposed to have covered the eroded remnants of this uplifted mass, and the Ouachita Mountains were thrust over it near the end of Pennsylvanian time. Orogenic movements in late Paleozoic time determined the form of all the uplifts. Conglomerates above the Wapanucka (Otterville) lime­ stone east of the Criner Hills mark the rising Wichita Mountains west of these hills. A contemporaneous break in the section is found in the Llano-Burnet and Marathon uplifts. The notable uplift of the eastern Wichita Mountains occurred soon afterward, in early Glenn time, for later Glenn sediments rest unconformably on sharply tilted and trun­ cated beds of Ordovician limestone. The Llano-Burnet uplift, the Bend arch, and the northeastern part of the Arbuckle Mountains were defined at this time. The most important Carboniferous movement in the Seminole area, along the Seminole-Cushing ridge and in the Nemaha Mountains, occurred at the same time. Ouachita folding began at about the same time, but the scarcity of conglomerate in adjacent outcrops of early Pennsylvanian rocks indicates that most of the folding occurred during middle Pennsylvanian time, contemporaneously with notable movements in the Arbuckle Mountains. Later in Pennsylvanian time the Ouachita Mountains were overthrust toward the northwest, overriding the east end of the Arbuckle Moun­ tains and the pre-Ouachita uplift. At about the same time the Arbuckle Mountains were brought to completion and the Marathon region was

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folded. The beds of conglomerate around the Arbuckle Mountains (and probably those around the Wichita Mountains), of late Pennsylvanian or early Permian age, were deposited on the beveled edges of older beds. All major folding was therefore completed by Permian time, and the shortening of the entire region due to compression from the south brought into juxtaposition rocks that were deposited many miles apart. Folding and warping were'spasmodic but frequent throughout Penn­ sylvanian and Permian time, as is shown by the correlation of logs of wells drilled for oil. The Permian and post-Permian orogenic move­ ments were not so great as the earlier movements, except in the Glass Mountains and in the west Texas basin, where they are connected with the Ancestral Eocky Mountains, but they compressed still further many of the older folds, uplifted some domes, and created new folds. Further­ more, the broad warping that accompanied and reelevated the uplifts caused depressions, such as the Anadarko and western Texas troughs, which were outlined by the end of Pennsylvanian time and were deep­ ened as sedimentation progressed. The most important movements after the post-Permian and post- Triassic folding were the early Cretaceous warping and the Tertiary warping, faulting, and folding.

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