s 14:GS: RPI60 ~. 1

STATE OF ILLINOIS HENRY HORNER, Governor DEPARTMENT OF REGISTRATION AND EDUCATION JOHN ]. HALLIHAN, Director

DIVISION OF THE STATE GEOLOGICAL SURVEY M. M. LEIGHTON, Chief URBANA

REPORT OF INVESTIGATIONS-NO. 60

PRELIMINARY GEOLOGIC MAP OF THE MISSISSIPPIAN FORMATIONS IN THE DONGOLA, VIENNA, AND BROWNFIELD QUADRANGLES

BY

STUART WELLER AND FRANK F. KREY

EXPLANATION AND STRATIGRAPHIC SUMMARY

BY

J. MARVIN WELLER

PRINTED BY AUTHORITY OF THE STATE OF ILLINOIS

URBANA, ILLINOIS 1939 STATE OF ILLI OIS HENRY HORNER, Governor DEPARTMENT OF REGISTRATION A D EDUCATIO:--J JOHN ]. HALLIHAN, Director

DIVISION OF THE STATE GEOLOGICAL SURVEY M. M. LEIGHTON, Chief URBANA

REPORT OF INVESTIGATIONS -NO. 60

PRELIMINARY GEOLOGIC MAP OF THE MISSISSIPPIAN FORMATIONS IN THE DONGOLA, VIENNA, AND BROWNFIELD QUADRANGLES

BY

STU ART WELLER AND FRANK F. KREY

EXPLANATION AND STRATIGRAPHIC SUMMARY

BY

J. MARVIN WELLER

PRINTED BY AUTHORITY OF THE STATE OF ILLINOIS

URBANA, ILLINOIS 1 9 3 9 STATE OF ILLINOIS HaN. H ENRY HoR NER, Go vernor DE PARTMENT OF REGISTRATION AND EDUCATION HaN. J oHN J. H ALLIHAN, Director

BOARD OF NATURAL RESOURCES A TD CO . SERVATION H aN . J oHN J. H ALLIHA , Chairman EosoN S. BAST I N, Ph.D., Geology H ENRY C. CowL ES , Ph.D., D.Sc., vVrLLIAM A. ToYES, Ph.D., LL.D., Forestry Chem.D., D.Sc., Chemistry ARTH UR C uTTS \V ILLARD, D.Fngr., Lours R. H owsoN, C.E., Engineering LL.D., President of the University WILLIAM TRELEA SE , D.Sc., LL.D., Biology of Illinois STATE GEOLOGICAL SURVEY DIVISION Urbana M. M. LEIGHTON, Ph.D., Chief ENID TowNLEY, M.S., Assistant to the Chief J ANE TITCOMB, M.A., Geological Assistant

GEOLOGICAL R ESOURCES GEOCHEMISTRY Coal G. H. CADY, Ph.D., Senior Geologist FRA NK H. R EED , Ph.D., Chief Chemist L. C. McCABE, Ph.D. w. F. BRADLEY, Ph.D. }AMES M. Sci-IoPF, Ph.D. G. C. FINGER, Ph.D. EARLE F. TAYLOR, I. S. HELE N F. AusTIN, B.S. CH ARLES C. BoLEY, M.S. Industrial Minerals Fuels J. E. LAMAR, B.S. G. R. YoH E, Ph.D. H. B. WILLMAN, Ph.D. CARL HARMA N, B.S. DouGLAS F. STEVENs, M.E. R oBERT M. GRoGAN, M.S. Industrial il.finerals J. s. TEMPLETON, A.B. J. S. MACHIN, Ph.D. Oil and Gas }AMES F. VANECEK, M.S. A. H . BEL L, Ph.D. G. V. CoH EE, Ph.D. Analytical FREDERICK SQUIRE S, B. S. 0. w. R EES, Ph.D. CHARLES W. CARTER, Ph.D. L. D. McVIc KER , B. S. F . C. MAc K NIGHT, Ph.D. GEORGE w. LAND, B. Ed. FRANK E. TIPPIE, B.S. P. w. HENLINE, B.S. RoY B. RALSTON, B.A. MATHEW KALI NOWSKI, B.S. Areal and Engineering Geology ARNOLD J. VERAGUTH, M.S. GEORGE E. EKBLAW, Ph.D. H ARRY McDERMITH, B.S. RICHARD F. FISHER, B.A . MI ERAL ECO OMICS Subsurface Geology W. H. Vo sKUIL, Ph.D., Mineral Economist L. E. WoRKMAN, M.S. GRACE N. OLIV ER , A.B. J. NoRMAN PAYNE, Ph.D. ELWOOD ATHERTON, Ph.D. M ERLYN B. BuHLE, M.S. EDUCATIONAL EXTENSION GoRDO N PR ESCOTT, B.S. Stratigraphy and Paleontology Don L. CARROLL, B.S. J. 1ARVIN WELLER, Ph.D. CH ALMER L. CooPER, M.S. PUBLICATIO S AND R ECORDS Petrography RALPH E. GRI M, Ph.D. GEORGE E. EKBLAW, Ph.D. RICHARDS A. R owLAND, Ph.D. CH ALMER L. CooPER, M.S. Physics D oROTHY RosE, B.S. R. J. PIER SO L, Ph.D. KATHRYN K. D EDMAN, M.A. DoNAL D 0. HoLLAND , M.S. ALMA R. SWEE EY , A.B. PA UL F. ELARDE, B.S. FRANCES HA RPER L EH DE, M.S. }ACK T uTTLE MEREDITH M. CALKINS

Consultants: Ceramics, C uLLEN \V ARNER P ARMELEE , M.S., D.Sc., Uni versity of Illinois; Pleistocene Invertebrate Paleontology, FRANK CoLLIN S BA KER , B.S., University of Illinois. Topographic Mapping in Cooperation with the United States Geological Survey. This Report is a Contribution of the Section of Geological R esources, Di vision of Stratigraphy and Paleontolog)·. ~ 2 (A7472-2M-10-39) Septemher 10, 1939 CONTENTS

PAGE Introd uction ...... 5 Field work ...... 5 Status of maps ...... 5 Iowa seri es ...... 6 Mountain Glen shale . 6 Springville shale ...... 6 Burlington-Keokuk formation . . 6 \.V arsaw-Salem limes tone .. . 7 St. Louis lim estone ...... 7 Ste. Genevieve limestone . . 7 Chester seri es ...... 8 R enault limestone ...... 8 Bethel sandstone ...... 8 P ai nt Creek formation 8 Cypress sandstone. 8 Golconda formation ...... 9 Hardinsburg sandstone ...... 9 Glen D ean formation. 9 Tar Springs sandstone ...... 9 Vienna limestone ...... 9 Waltersburg sandstone .. . . 10 Menard limes tone ...... 10 P alestine sandstone ...... 10 Clore formation ...... 10 D egonia sandstone ...... 10 Kinkaid limestone ...... 10 Pre-P ennsylvanian unconformity...... 11 P ennsylvanian system ...... 11 Cretaceous and T ertiar y deposits ...... 11 Structure ...... 11

ILLUSTRATIONS

FIGURE PAGE Index map of southern Illinois showing the location of A, Dongola; B, Vi enna; and C, Brown- fi eld quadrangles ...... 6

P LATE I Preliminary geologic Map of Dongola, Vienna, and Brownfield quadrangles...... (In pocket)

[3J PRELIMINARY GEOLOGIC MAP OF THE MISSISSIPPIAN FORMATIONS IN THE DONGOLA, VIENNA, AND BROWNFIELD QUADRANGLES

BY

STUART \VELLER AND FRANK F. KREY

EXPLANATION AND STRATIGRAPHIC SUMMARY

BY

J. MARVIN WELLER

INTRODUCTION Survey. 1 The geology of the Carbondale quadrangle, which lies north of the Dongola HE l\t1ISSISSIPPIAN rocks of Illinois quadrangle and includes parts of Jackson, T crop out in three distinct areas along Williamson, Union, and Johnson counties the western and southern borders of the has likewise been described. 2 The western State. The northernmost of these is the part of this third area of Mississippian out­ largest and extends along Mississippi Rive_r crops will be described in a future Report from Mercer County on the north to Madi­ of Investigations devoted to the pre-Penn­ son County on the south and also includes sylvan ian geology of the Alto Pass, Jones­ the outcrops along Illinois and Spoon rivers bora, and Thebes quadrangles. as far north as Fulton County. The second area occupies portions of St. Clair, Monroe, FrELD WoRK Randolph, and northwestern Jackson coun­ The Brownfield quadrangle was mapped ties extends for about 90 miles along the by Stuart Weller in 1916-18 and the Vienna bluffs of Mississippi River from a short di s­ quadrangle in 1918-19. In 1925 the map­ tance below East St. Louis to about 20 miles ping of the Brownfield quadrangle was re­ below Chester, and includes an area e~tend­ vised. Frank F. Krey mapped the Dongola ing eastward from the bluffs to a _max1mu~ quadrangle in 1921. width of about 15 miles. The th1rd area IS The following descriptions of formations in the extreme southern portion of the State, are based largely on manuscript reports on and extends as a belt ranging from 6 to 20 "The Geology of parts of Johnson and Pope miles in width from Union County on the co unties," by Stuart Weller, and "Geology west to Hardin County on the east. of the Dongola quadrangle," by Frank F. This report is concerned with the cen­ Krey. tral part of the third of these areas and describes the geology of those portions of STATUS OF MAPS Union, Johnson, Pope, Alexander, Pulaski , The separate quadrangle maps were never and Massac counties included within the completed for publication. Because of the Dongola, Vienna, and Brownfield qua~­ present need for the geologic information rangles (fig. 1). The eastern part of t~1 s southern area of Mississippian outcrops, m­ I Weller, Stuart, and others, The geology o~ H~rdin County and the adjoining part of Pope County: Illm01s State Geol. cluding Hardin and the adjoining _po rti~n Survey Bull. 41, 1920. of P ope County, has been descnbed m 2Lamar, J. E., Geology and mineral resources of the Car­ bondale quadrangle: Illinois State Geol. Survey Bull. 48, Bulletin +1 of the Illinois State Geological 1925 . [5] 6 MISSISSIPPI/JN FORMATIONS they are issued at this time in preliminary outline form on a sectionized base and show the areal distribution of the various forma­ tions on a scale similar to that of the stand­ ard fifteen minute topographic quadrangles of the U. S. Geological Survey. They have been traced directly from the original manu­ script geologic maps without alteration or addition and are intended to be used in con­ junction with the engraved quadrangle topo­ graphic maps. They are preliminary and subject to correction. The geologic mapping is incomplete in certain critical areas where additional field studies are necessary, and the strata exposed FIG. 1.- Index map of southern Illinois showing in some small fault blocks have not been the location of A, Dongola; B, Vienna; and C, identified. P articular attention is directed Brownfield quadrangles. to the following areas: Mountain Glen shale.-This formation 1) Dongola quadrangle. Because it is of Upper Devonian or Lower Mississippian thin and rarely well exposed the Bethel age consists of hard black shale about 50 sandstone is not shown separating the Re­ feet thick. It crops out only in the south­ nault and Paint Creek formations. It is, west part of the Dongola quadrangle, where however, probably present at most places. it occurs at the foot of the bluffs in sees. 2) Central part of Brownfield quad­ 17, 20, and 21, T. H- S, R. 1 W. It is well rangle. Sandstone occupying one or more exposed on the south slope of the isolated small fault blocks has been doubtfully hill near the center of sec. 20, but easily identified. The Chester sandstones are so accessible and better outcrops are present in similar that they cannot be certainly identi­ the Jonesboro quadrangle south of the road fied except where their relations to the near the west line of sec. 11 and below the associated limestone-shale formation can be spillway of the dam at the State Pond near observed. the middle of the S. Vz sec. 1+, T. 12 S., R. 2 W. It overlies the Alto formation 3) Southwest corner of Brownfield quad­ (Devonian) unconformably and is likewise rangle. Sandstones exposed in some of the succeeded unconformably by the Springville fault blocks have not been identified. shale. It is locally absent in the Jonesboro 4) Fault block southwest of Reeves­ quadrangle. ville. Sandstone included in this fault block Springville shale.- This formation over­ was identified as Hardinsburg in the Brown­ lies the Mountain Glen shale north of Mill field quadrangle and Tar Springs in the Creek in the southwestern corner of the Vienna quadrangle. The latter is probably Dongola quadrangle. In this area it is 25 correct. to 30 feet thick and consists of greenish shale. The lower 8 to 10 feet is soft but IOWA SERIES higher beds become increasingly siliceous The Kinderhook group is represented in and the upper portion strongly resembles the Dongola quadrangle by the greenish chert. The harder portion of the formation Springville shale and possibly also by the weathers to iron-stained chips whose surfaces underlying black Mountain Glen shale. are commonly mottled red, blue, and brown. The Osage and Meramec groups consist It may be seen north of the road near the of a thick conformable sequence of lime­ center of sec. 21, T. 14 S., R. 1 W., and an stone which undoubtedly includes strata excellent exposure occurs in the Jonesboro equivalent to the various formations of the quadrangle beside State Highway No. 1+6 standard Mississippian section, but the for­ in the NE. }4 sec. 23, T. 12 S., R. 2 W. mation boundaries are indistinct and it is Burlington-Keokuk formation.- Strata not possible to separate definitely all of the of Burlington-Keokuk age are mainly con­ formations that are recognized elsewhere. fined to the hills west of Mill Creek in the DONGOLA, VIENNA, AND BROWNFIELD 7 southwest part of the Dongola quadrangle. are well exposed along the road near the They consist of about 300 feet of fine­ center of sec. 17, T. 13 S., R. 1 W. Oolite grained dark bluish-gray limestone, which may be seen along the road west of Dongola may be more or less siliceous, and banded in the NW. ~ sec. 25, T. 13 S., R. 1 W. chert. At some places parts of the forma­ Upper St. Louis beds occur in the south­ tion consist entirely of chert but elsewhere west bank and bed of a creek in the NW. chert may constitute no more than ten per 0 sec. 23, T. 13 S., R. 1 W. cent of the rock. Both limestone and chert Ste. G enevieve limestone.-The outcrop rarely occur in beds more than one foot of this formation extends southeast from thick. Good exposures are present at the Anna to White Hill and Belknap. It over­ bridge over Mill Creek in the NW. ~ sec. lies the St. Louis limestone conformably 22 and in the hillside north of the road in and attains a thickness of about 300 feet. the NW. ~ sec. 21, T. 1+ S., R. 1 W. In Hardin County, Illinois, and in western Warsaw-Salem limes tone.-This lime­ Kentucky the Ste. Genevieve is subdivided stone crops out northeast of Mill Creek, into three members, the Fredonia limestone· from the we tern boundary of the Dongola at the bottom, the Rosiclare sandstone in quadrangle to Wetang, and is about 200 the middle and the Levias limestone at the to 250 feet thick. It appears to be con­ top. These members are recognized in the formable with both underlying and over­ Dongola quadrangle but because of inade­ lying beds. Although strata equivalent in quate outcrops they cannot be separately age to both the Warsaw and Salem forma­ mapped. In addition to these a variable tions as recognized farther north in the succession of clastic beds including some Mississippi Valley are undoubtedly present, limestone overlies the Levias limestone in they cannot be distinguished in southern Union County and for these the name Illinois, where they consist mainly of light Hoffner member is proposed. gray coarsely granular crinoidal limestone The Fredonia member consists of massive in massive beds that commonly spall off in limestone in beds generally three to four plates parallel to the exposed surface. The feet thick which vary considerably in lithol­ lower portion includes beds that are finely ogy. Some of them are similar to the under­ granular and bluish-gray, and some chert lying St. Louis formation but commonly is present in this and the uppermost part of they are somewhat lighter colored and the formation. The best exposure of the coarser textured. Beds of w hite more or lower part of the formation is in the old less cross-bedded oolite are present at several quarry in a bluff about 1 Yz miles north of horizons, and many of the other laye rs con­ Ullin. Higher beds are well shown in the tain scattered oolites. Some chert is pres­ W. Y2 sec. 28, T. 13 S., R. 1 W. ent, particularly in the lower part and in the darker-colored and finer textured laye rs, St. Louis limestone.-The St. Louis lime­ and a few more or less sandy beds occur in stone is about 350 feet thick in the Dongola the upper part. This member is 17 5 to 200 quadrangle and crops out in a zone three feet thick and is very well exposed in the to four miles wide extending southeast from quarries of the Anna Quarry Company east south of Anna to the Cache River bottoms of Anna and the Charles Stone Company near Perks. It consists mainly of medium­ at White Hill. grain ed dark gray strata with more or less interbedded granular limestone resembling The Rosiclare member is a fine-grained the underlying Warsaw-Salem, though dark­ more or less calcareous sandstone whose er colored. The lowest 25 to 30 feet of the thinner layers are commonly separated by formation is dark gray fine-textured siliceous greenish shaly partings. It is 10 to 12 feet limestone, and the upper part is composed thick and is rarely well exposed. This mem­ of dark bluish-gray beds that are fine-grained ber may be best seen at the top of the face to sublithographic in texture. Chert is pres­ of the Charles Stone Company's quarry at ent throughout the entire formation but is White Hill. most abundant in the finer grained portions. The Levias member is similar to the Some oolitic beds occur but the oolites are Fredonia except that it is commonly less generally smaller and darker colored than cherty and can be identified only where the in the Ste. Genevieve. The lower strata Rosiclare sandstone is exposed beneath it. 8 1l1ISSISSIPPIAN FORMATIONS

The Levias member probably attains a thick­ ledges separated by variable amounts of ness of about 40 feet. shale are somewhat massive and in part The Hoffner member lithologically re­ notably cross-bedded. A little chert is pres­ sembles strata of the Chester series but its ent in the upper part. Shale is rarely ex­ fossils include characteristic Ste. Genevieve posed and is mainly gray or greenish but rather than Chester species. It appears to red beds are present in Union County. have a thickness of between 50 and 80 feet B ethel sandstone.-The Bethel sandstone and consists mainly of sandy shale and fine­ attains its greatest thickness of about 130 grained standstone that is locally rather feet between Cave and Barren creeks in massive. With these strata are associated the southeast corner of the Brownfield red shales at several horizons and in the quadrangle and is about 80 feet thick in the middle part of the member are one or more bluffs north of Bay Creek. West of Pope limestones. The most characteristic type County, however, it is a thin and generally of limestone occurs in thin lenticular sandy inconspicuous formation and unlike other and somewhat oolitic beds that are mottled Chester sandstones has little effect upon red and green. Other limestones closely topography. Near Belknap it is about 30 resembling those of the Fredonia and feet thick but elsewhere rarely exceeds 15 Levias members attain a thickness of 10 feet and appears to be entirely absent locally. feet or more and are locally massive and It is believed to overly the Renault lime­ richly oolitic. This member is well exposed stone unconformably and is well exposed along Swan Creek northeast of Anna in the above that formation in the railroad cut E. Vz sec. 17, T. 12 S., R. 1 W. and east at Indian Point in the SW. ~ sec. 32, T. of Hoffner school in the W. Yz sec. 8, T. 13 S., R. 3 E. 13 S., R. 1 E. The Bethel is a fine-grained yellowish­ brown cross-bedded sandstone that is gen­ CHESTER SERIES erally ve ry massive and cliff-forming where All of the formations of the standard it is thick, but it is thin-bedded, shaly, and Chester section except the Aux Vases sand­ rarely well exposed where it is thin. stone are present in this area. The Bethel Paint Cree k formation.-The Paint sandstone is thin and possibly discontinuous Creek formation consists principally of shale except near Ohio River but the Walters­ and attains a thickness of 40 to 60 feet, burg sandstone achieves its best development being thickest to the east. The shale is in this region. On the whole, the Vienna commonly grayish or greenish and where quadrangle is a favorable area in which to fresh may be nearly black. Locally it observe the succession of the Chester for­ weathers to a conspicuous red color that mations. They are little disturbed by fault­ is characteristic of this formation. Lime­ ing and as there is no glacial drift most of stone is generally present, in thin laye rs, the gently dipping sandstones form more but may be entirely lacking. It is light or less continuous ridges that sharply sepa­ colored, more or less crystalline, but com­ rate the various limestone-shale formations monly impure, and locally appears to grade with which they alternate. into calcareous sandstone or become con­ Renault limestone.-This formation glomeratic. Because of its shaly nature this crops out along a narrow zone extending formation is rarely well exposed. A good from the northwest corner of the Dongola outcrop may be seen along the second ary quadrangle southeast to a point five or six road in the SW. Y-J_ sec. 3+, T. 13 S., R. miles beyond U. S. Highway +5 and also 3 E. in the bluffs on both sides of Bay Creek Cypress sandstone.-This formation is adjacent to Ohio River. It is well exposed the most persistently thick and mass ive in a quarry near Belknap in the NE. Y-J_ sandstone in the Chester se ries. It forms sec. 1, T. 1+ S., R. 2 E. an escarpment that extends from the north­ The Renault overlies the Ste. Genevieve west corner of the Dongola quadrangle limestone unconformably and attains a thick­ so utheast to the bottomlands that connect ness of 60 or more feet. It consists mainly the valleys of Cache Rive r and Bay Creek. of hard gray limestone that is more or less Other bluffs produced by this formation crystalline and locall y oolitic. Individual are present both north and south of Bay DONGOLA, VIENNA, AND BROWNFIELD 9

Creek farther to the east. The thickness in Union County it is probably nowhere of the Cypress sandstone is difficult to esti­ more than 50 feet thick. As it thins west­ mate but it probably exceeds 100 feet nearly ward the Hardinsburg sandstone becomes everywhere. It consists of gray to yellowish somewhat more thin-bedded and shaly and medium-grained sand that weathers brown. locally includes dark shale. It is excellent­ The main central part of the formation is ly exposed at the top of the bluff southeast very massive, but thin-bedded strata are of Brownfield. present in both the lower and upper parts. Glen Dean formation.-The interbedded Cross-bedding is common. The formation limestones and shales of the Glen Dean is well exposed near the village of Cypress formation are similar to those of the Gol­ but was named for Cypress Creek many conda and can be distinguished with certain­ years before that town was established. The ty only by fossils. In general, limestones contact of the formation with the under­ are abundant in the upper part and shales lyi ng Paint Creek is well exposed in the in the lower, although this situation may Ohio River bluffs just below Golconda be reversed. A little chert is locally present along the road leading to Dam No. 51. and some oolite occurs near the top of the Golconda fonnation.-The Golconda formation in the Dongola quadrangle. The formation consists of interbedded limestones thickness of the formation is generally about and shales. At most places limestone appears 60 to 80 feet but locally east of Vienna the to dominate the upper part and also to be upper beds appear to be absent and the Glen relatively abundant in the lower part, but Dean is represented by about 40 feet of the middle part consists almost exclusively shale. The formation is well exposed bv of shale. The limestones are generally more the roadside in the north-central part o-f or less crystalline and vary from light gray sec. 35, T. 12 S., R. 1 E. to bluish-gray in color. Some oolite is local­ Tar Springs sandstone.-The Tar ly present. The shales vary from nearly Springs is a fine-grained cross-bedded sand­ black to light gray or greenish and some stone similar to the Hardinsburg and Cy­ are very calcareous. A little reddish shale press sandstones and forms a third scarp is locally present. The Golconda formation north of and parallel to the others. Like is generally more than 100 feet thick and the Hardinsburg it is variable in lithology, attains its greatest thickness of about 150 massive in some areas and thin-bedded or feet south of Vienna, but in so utheastern even shaly in others. In general the more Johnson County south and west of Gann­ massive beds occur in the upper and lower town it seems to be no more than +O feet parts of. the formation separated by shaly thick. The formation is well exposed by strata that include a coaly horizon in John­ the roadside in the SW. !4 sec. 2, T. 13 S., son and Pope counties. The coaly horizon R. 1 E. is exposed by the roadside in the NW. ~ Hardinsburg sandstone.-The Hardins­ SE. Y4 sec. 6, T. 13 S., R. 3 E. The Tar burg sandstone is similar to the Cypress in Springs sandstone is thickest to the east general character and forms a well-marked where in eastern Pope County it attains a escarpment north of and parallel to the maximum of 100 to 150 feet. It is prob­ series of ridges capped by the Cypress for­ ably nowhere more than 100 feet and it mation. It is most massive in its lower part appears to average 60 to 80 feet thick in and is probably separated from the Gol­ Johnson and Union counties but locally, conda formation by an erosional uncon­ northwest of Grantsburg, it is little more formity that accounts for the variable thick­ than 40 feet thick. Its contact with shale ness of the underlying formation. The of the underlying Glen Dean formation Hardinsburg sandstone is thickest to the may be seen along Highway 1+6 three miles east and thins to the west. It is 100 feet east of Vienna. thick where it i well exposed in the Ohio Vienna limestone.-This formation con­ River bluffs above Golconda, just east of sists principally of dense bluish-gray chert­ the Brownfield quadrangle. This thickness bearing limestone with some dark shale, continues into Johnson County, where the particularly in the upper part of the forma­ formation thins irregularly and locally is tion, but locally the shale exceeds the lime­ ap parently no more than 30 feet thick, and stone. The limestone is very siliceous and 10 MISSISSIPPIAN FORMATIONS commonly weathers to porous more or less most massive and thickest development oc­ ocherous residuum. This residuum and the curs east of Bay Creek in the vicinity of dark chert are characteristic of the forma­ Flatwoods, where it is about 80 feet thick. tion. This formation ranges in thickness Both to the east and west it thins to +O or from a maximum of 60 to 70 feet in the 60 feet. Massive beds may be present east to 30 or +O feet in the west. The best locally in the upper part. This sandstone exposure is along the cut of Illinois Central may be seen overlying the Menard forma­ Railroad in sec. 12, T. 13 S., R. 4 E. where tion in the cut at the north portal of the a thin coal is present at the base of the Illinois Central Railroad tunnel in sec. 36, limestone. At the north end of the cut T. 12 S., R. 4 E. part of the limestone is completely weath­ Clore formation .- This formation con­ ered to the characteristic cherty residuum. sists mainly of shale, although several feet Jf/ altersburg sandstone.-The Walters­ of limestone in thin beds separated by shale burg is an important sandstone only in the is commonly present in the upper part, Brownfield quadrangle and the eastern part and thin lenticular limestones and calcare­ of the Vienna quadrangle. Its maximum ous nodules occur elsewhere. The lime­ thickness of 60 to 70 feet is attained along stones are generally fine-grained and dark Bay Creek northwest of Grantsburg, but it bluish-gray. The shales are mostly dark is well developed as far east as Waltersburg, gray to greenish and more or less calcareous. in which areas it is very massive, produces The Clore formation attains a thickness of scarps, and stands in vertical cliffs closely 30 to 40 feet at most places but locally may resembling the Cypress sandstone. To the be no more than 20 feet thick. It is best east and west it thins rapidly, becomes shaly, exposed in a railroad cut in the SW. Y-J and probably nowhere exceeds 30 or 40 feet SW. !;4 sec. 23, T. 12 S., R. 2 E., about in thickness. In its thinner development the half way between West Vienna and Bun­ Waltersburg includes thin layers of very combe. fine-grained tough sandstone which charac­ Degonia sandstone.-The Degonia is one teristically break into blocks two to four of the thicker and more massive of the inches wide and thick and a foot or more Chester sandstones and locally resembles long. the Cypress sandstone and the lower massive Jl,fenard limestone.-The Menard lime­ sandstones of the Pennsylvanian system. It stone is one of the most uniform formations is about 100 feet thick in the Vienna quad­ of the Chester series. In southern Illinois it rangle and locally produces a well-marked is generally about 100 feet thick but may scarp, but its effect on the topography else­ thin slightly from east to west. The lime­ where is masked by the more prominent stone is mostly fine-grained and bluish-gray scarp of the Pennsylvanian sandstone. East­ and weathers with smooth surfaces, al­ ward, in the Brownfield quadrangle, the though lighter colored more crystalline lay­ formation becomes somewhat thinner and ers are not uncommon. Individual strata less massive. The lower beds of the Degonia are generally a foot or less thick with uneven are commonly thin-bedded and somewhat surfaces and are separated by partings or shaly, and the massive strata in the upper layers of shale. Chert is more common than part are generally separated by thinner in any of the lower Chester limestones layers. Some of its massive beds are well except the Vienna. Considerable shale is exposed near Glendale in the Brownfield present, particularly in the middle and lower quadrangle, and it may be seen overlying parts. This formation is best exposed in the the Clore formation in a road cut in the cut at the south portal of the Illinois Central NE. Y4 SE. Y-t sec. 19, T. 12 S., R. 4 E. Railroad tunnel in sec. 1, T. 13 S., R. 4 E., Kinkaid limestone.-This formation and the limestone may be seen also along closely resembles the Menard in lithology Highway 37 half a mile north of West and bedding. Chert, however, is much Vienna. more abundant and marks the weathered Palestine sandstone. -This formation is outcrop of the Kinkaid at most places. generally thin-bedded or even shaly and Light-colored granular limestone is likewise dc;,ts ' not produce a conspicuous scarp like somewhat more abundant than in the Men­ several of the other Chester sandstones. Its ard, and red beds are present at many places DONGOLA, VIENNA, AND BROWNFIELD 11 in the shaly lower portion of the Kinkaid. much more locally present in the area to The formation may attain a maximum thick­ the north. They consist of various types of ness of about 140 feet, but it was subject clays, sands, and gravels, some of which are to considerable pre-Pennsylvanian erosion partly cemented with limonite. and is generally less than 100 feet thick and locally has been reduced to 60 or 70 feet. It STRUCTURE is best exposed in the Illinois Central Rail­ The area covered by this report lies at the road cut at Robbs in the Brow nfield quad­ southern tip of the Illinois basin into which rangle and here its gradation into the under­ all of the formations dip. The strike of the lying Degonia sandstone may be observed. strata across the Dongola quadrangle is Reddi sh Kinkaid shale is exposed just south nearly northwest-so utheast. Dips to the of the road in the NE. 0 NE. 0 sec. 20, T. 12 S., R. E. northeast range in general from 1 to 2 + degrees, the older strata dipping a little PRE-PENNSYLVANIA UNCONFORMITY more steeply than the younger ones. In the Vienna quadrangle the strike becomes more The Mississippian and Pennsylvanian nearly east-west and dips of the strata be­ systems are separated by an important ero­ come generally more gentle. sional unconformity. Erosion in this part of southern Illinois, however, was not There are several faults, mostly trending severe and nowhere was the Kinkaid lime­ northwest-southeast or northeast-southwest , stone at the top of the Chester series com­ in the area but displacements are small and pletely removed before the first Pennsyl­ exceed 100 feet at only a few places. vanian sediments were laid down. Erosion Extending northeast-southwest across the at this systemic contact is, however, reflected Brownfiel d quadrangle is the Dixon Springs bv the variable thickness of the Kinkaid graben, one of the most prominent struc­ n:hich ranges from less than 70 to 140 feet tural fe atures of southern Illinois. This or more. graben occurs in the midst of a complex series of northeast-trending faults which P ENNSYLVANIAN SYSTEM parallel the main mineralized veins of the fluorspar district farther east in Hardin Pennsylvanian beds overly the l\!Iississip­ County, Illinois, and Crittenden County, pian in the northern parts of the Vienna Kentucky. The graben is not a simple one and B rownfield quadrangles and extend because it is bounded by fault zones rather southwestward in the Dixon Springs graben than single faults and is itself faulted. The nearly to Bay Creek. The most prominent combined displacements of the faults that member of the basal Pennsylvanian Casey­ bound it amount to nearly 1000 feet at some ville formation is the Lick Creek sandstone. places. In it Pennsylvanian beds extend This is a thick massive ridge- and cliff-form­ southwest nearly to Bay Creek. ing sandstone similar to the better developed sandstones of the Chester series but dis­ No reversals of dip are known except in tingu ished from them by the common but a few of the smaller fault blocks and no more or less local occurrence of rounded anticlinal structures have been discovered quartz pebbles. Below the Lick Creek sand­ in this part of southern Illinois. stone at most places is the basal Wayside The structure of the Paleozoic rocks member of the Caseyville formation, con­ south of Cache River and Bay Creek is sisting mainly of more or less sandy shale uncertain because they are covered by Cre­ and thin-bedded sandstone. taceous and Tertiary deposits, and outcrops of the indurated rocks are few. So far as CRETACEOUS AND TERTIARY D EPOSITS known, however, the strata dip gently to Unconsolidated Cretaceous and Tertiary the northeast and north and are broken by sediments are extensively distributed south faults similar to those observed farther to of Cache River and Bay Creek and are the north.