R. M. Kosanke J. A. Simon

H. B. Wiflrnan

Illinois State Geolo Urbana, Illinois

PRINTED BY AUTHORITY OF THE STATE OF ILLINOIS STATE OF ILLINOIS HON. WILLIAM G. STRATTON, Governor DEPARTMENT OF REGISTRATION AND EDUCATION HON. VERA M. BINKS, Director

BOARD OF NATURAL RESOURCES AND CONSERVATION

HON.VERA M. BINKS,Chairman W. H. NEWHOUSE,PH.D., Geology ROGERADAMS, PH.D., D.Sc., LL.D., Chemistry ROBERTH. ANDERSON,B.S., Engineering A. E. EMERSON,PH.D., Biology L~u.1s H. TIFFANY,PH.D., PD.D., Forestry DEANW. L. EVERITT,E.E., PH.D., University of Illinois PRESIDENTDELYTE W. MORRIS,PH.D., Southern Illinois Univef-sity

GEOLOGICAL SURVEY DIVISION JOHN C. FRYE,PH.D., D.Sc., Chief FULL TIME STAFF JOHN C. FRYE, PH.D., D.Sc., Chief ENIDTOWNLEY, MS., GeoIogi~t HELENE. MCMORRIS,Secretary VELDAA. MILLARD,Junior and Assistant to the Chief to the Chief Assistant to the Chicf EMERITI M. M. LEIGHTON,PH.D., D.Sc., ChieJ, Emeritus ARTHURBEVAN, PH.D., D.Sc., Principal Geologist, Emeritus GILBERTH. CADT,PH.D.,. Senior Geologist, Head of Coal Section, Emeritus ROBERTJ. PIERSOL,PH.~., Physicist, Head of Ph-vsics Section, Emeritus GEOLOGICAL GROUP M. L. THOMPSON,PH.D., Principal Geologist FRANCESH. ALSTERLUND,A.B., Research As~istant COAL INDUSTRIAL MINERALS JACKA. SIMON,M.S., Geologist arrd Head J. E. LAMAR,B.S., Geologist and Head ROBERTM. KOSANKE,PH.D., Geologist JAMESC. BRADBURY,PH.D., Geologist JOHNA. HARRISON,M.S., Associate Geologist. DONALDL. GRAF,PH.D., Geo!ogist PAULEDWIN POTTER, PH.D., Associate Geologzst JAMESW. BAXTER,PH.D., Assistant Geologist WILLIAMH. SMTTH,M.?., Associate Geologist KENNETHE. CLEGG,M.S., Assistant Gedogi~t MARGARETA. PARKER,M.S., Assi.ctant Geologist STRATIGRAPHY AND AREAL GEOLOGY DAVIDL. REINERTSEN,A.M., Assistant Geologist H. R. WILLMAN,PH.D., Geologist and Head OIL AND GA4S ELWOODATHEKTON, PH.D., Geologist A. H. BELL,PH.D., Geologist and Head CHARLESW. COLLINSON,PH.D., Geologist LESTERL. WHJTING,MS., Geologixt HERBERTD. GLASS,PH.D., Geologist WAYNEF. MEENTS,Associate Geological Engineer DAVIDH. SWANN,PH.D., Geologist MARGARET0. OROS,B.A., Assistnnt Geologist T. C. BUSCHBACH,PH.D., Associate Geologist DAVIDL. STEVENSON,M.S., Assistant Geologist LOISS. KENT,PH.D., Associate Geologist JACOBVAN DEN BERG, M.S., Assistant Geologist ROMAYNES. ZIROLI,B.A., Research Assistant RICHARDH. HOWARD,M.S., Research Assistant ROBERTW. FRAME,Supervisoyv Technical Assistant RONALDA. YOUNKER,BS., Research Assistant JOSEPHF. HOWARD,Assi~tant PETROLEUM ENGINEERING CARLW. SHERMAN,M.S., Petroleum Engineer and GROUND-WATER GEOLOGY AND GEOPHYSI- Head CAL EXPLORATION RICHARDF. MAST,B.S., Assistazt Petroleum Engi- neer GEORGEB. MAXEY,PH.D., Geologist and Head RORERTE. BERGSTROM,PH.D., Geologist CL4Y RESOURCES AND CLAY MINERAL MERLYNB. BUHLE,M.S., Geologist TECHNOLOGY JAMESE. HACKETT,PH.D., Geologist W. ARTHURWHITE, PH.D., Geologist and Head GROVFRH. EMRICH,M.S., Assistant Geologist T. S. HOSKING,PH.D., Special Associate Geologist JOHNP. KEMPTON,M.A., Assistant Geologist ~VALTERE. PARHAM,M.S., Assistant Geologist LYLED. MCGINNIS,MS., Assistant Geophvcisist LOWELLA. REED,B.S., As~istantGeologist AND ARTHURJ. ZEIZEL,M.S., dssistant Geologist MAPPING MARGARETJ. CASTLE,Assistant Geologic Draftsman GEORGEE. EKBLAW,PH.D., Geologist and Head (on leave) WILLIAMC. SMITH,M.A., Associate Geologist CHEMICAL GROUP GRACEC. FINGER,B.S., Research Assistant PHYSI CAI. CHEMlSTRY COAL CHEMISTRY J. S. MACHIN,PH.D., Chemist and Head G. R. YOHE,PH.D., Chemist and Head DANIELL. DEADMORE,PH.D., Associate Chemist JOSEPHM. HARRIS,B.A., Research Assistant NEILF. SHIMP,PH.D., Associate Chemist JUANITAWITTERS, MS., Associate Physicist CHEMICAL ENGINEERING ANALYTICAL CHEMISTRY H. W. JACKMAN,M.S.E., Chemical Engineer and Head R. J. HELFINSTINE,M.S., Mechanical and Adminis- 0. W. REES,PH.D., Chemist and Head trative Engineer L. D. MCVICKER,B.S., Chemist B. J. GREENWOOD,B.S., Mechanical Engineer WILLIAMJ. ARMON,M.S., Associate Chemist ROBERTL. EISSLER,PH.D., Associate Chemical CHARLESW. BEELER,M.A., Assistant Chemist Engineer DAVIDB. HECK,B.S., Research Assistant WALTERE. COOPER,Technical Assistant JOHNF. HERSCHELMAN,Research Assistant JOHNP. MCCLELLAN,Technical Assistant EFFIEHETISHEE, B.S., Research Assistant EDWARDA. SCHAEDE,Technical Assistant ~OHNK. KUHN.Research Assistant GEORGE R. JAMES,Technical Assistant BENJAMINF. MANLEY,Technical Assistant FLUORINE CHEMISTRY G. C. FINGER,PH.D., C,bemist and Head X-RAY DONALDR. DICKERSON,M.S., As~ociatcChemist W, F. BRADLEY,PH.D., Chemist nnd Head LAURENCED. STARR,PH.D., Associate Chemist MINERAL ECONOMICS GROUP W. H. VOSKUIL,PH.D., Principal Miner01 Economist HUBERTE. RISSER,PH.D., Mineral Economist W. L. BUSCH,A.B., Associate Mineral Economist

ADMINISTRATIVE GROUP EDUCATIONAL EXTENSION SPECIAL TECHNICAL SERVICES GEORGEM. WILSON,M.S., Geologist and Head WILLIAMDALE FARRIS, Research Associate I. EDGARODOM, M.S., Assistant Geologist BEULAHM, UNFER,Technical Assistant BETTYJ. HANAGAN,M.S., Research Assistant A. W. GOTSTEIN,Research Associate GLENNG. POOR,Research Associate* GENERAL SCIENTIFIC INFORMATION GILBERTL. TINBERG,Technical Assistant WAYNEW. NOFFTZ,Supervisory Technical Assistant CARLENER. LYDY,Technical Assistant DONOVANM. WATKINS,Technical Assistant JOANSEVON, B.A., Technical Assistant MARYM. SULLIVAN,Supervisory Technical Assistant EMILYS. KIRK, Supervisory Technical Assistant PUBLICATIONS RUBYD. FRISON,Technical Assistant DOROTHYE. ROSE,B.S., Technical Editor CLERICAL SERVICE MEREDITHM. CALKINS,Geologic Draftsman BETTYM. LYNCH,B.ED., Assistant Technical E+itor KARENF. JENKS,Clerk-Stenographer II LLEWELLYNW. COOPER,B.S., Assistant Geologzc RITAJ. NORTRUP,Clerk-Stenographer I1 Draftsman ANITAF. ROOSEVELT,Clerk-Stenographer 11 MIRAN. RODWAN,Assistant Geologic Draftsman MAGDELINEE. HUTCHISON, Clerk-Stenographer I SUSANE. SHANNON,Clerk-Stenographer I MINERAL RESOURCE RECORDS EDNAM. Y EARGIN, Clerk-Stenographer I LEONAWHITESELL, Clerk-Typist I1 VIVIANGORDON, Head DOROTHYJ. GERDES,Clerk-Typist I HANNAHFISHER, Supervisory Technical Assistant LINDAG. GOLDMAN,Clerk-Typist I KATHRYNL. GRONBERG,B.S., Research Assistant RUTHTEM. HARRINGTON,Clerk-Typist I LINDAL. BENNETT,Technical Assistant WILLIAML. MATHIS,Messenger-Clerk I1 BARBARAG. DOBBINS,B.A., Technical Assistant MARILYNJ. LILLY,B.S., Technical Assistant AUTOMOTIVE SERVICE JANELUSK, Technical Assistant GLENNG. POOR,In Charge* ELIZABETHSPEER, Technicnl Assistant ROBERT0. ELLIS,Automotive Shop Foreman DAVIDB. COOLEY,Automotive Mechanic TECHNICAL RECORDS EVERETTEEDWARDS, Automotive Mechanic BERENICEREED, Supervisory Technical Assistanr MIRIAMHATCH, Technical Assistant HELENE. SCHROEDER,Technical Assistant RESEARCH AFFILIATES RICHARDC. ANDERSON,PH-D., Augustana College LIBRARY DOUGLASA. BLOCK,MS., Wheaton College OLIVEB. RUEHE,B.S., Geological Librarian J HARLENBRETZ, PH.D., University of Chicago CAROLS. MADDEN,B.A., Technical Assistant FRANKL. DOYLE,PH.D., St. Mary's University of San Antonio FINANCIAL RECORDS S. F. HARRIS,JR., PH.D., Southern IIlinois University A. BYRONLEONARD, PH.D., University of Knnsas VELDAA. MILLARD,In Charge THOMASG. PERRY,PH.D., Indiana University VIRGINIAC. SANDERSON,B.S., Clerk lV CARLB. REXROAD,PH.D., University of Houston MARJORIEJ. HATCH,Clerk-Typist IIl WALTERD. ROSE,B.S., University of IlIinois BETTYB. SIMS,B.A., Clerk-Typist I1 ALANJ. SCOTT,PH.D., University of Texas JANICESCHULTHES, Clerk-Typist I PAULR. SHAFFER,PH.D., University of Ilinois NORMANSTREET, PH.D., University of Illinois HAROLDR. WANLESS,PH.D., University of IlIinois Topographic mapping in cooperation with the PAULA. WITHERSPOON,PH.D., University of Cali- United States Geological Survey fornia FREDERICKD. WRIGHT,M.S., University of 1lbnois ."Divided time CONSULTANTS GEORGEW. WHITE,PH.D., University of Illinois June 1, 1960 RALPHE. GRIM:PH.D., University of Iliinois CONTENTS

PART I-THE PROBLEM OF CLASSIFICATION PAGE Introduction ...... I0 Nature of Pennsylvanian strata ...... 11 General character ...... 11 Thickness of units ...... 11 Persistence of units ...... 13 Cyclical sequences ...... 13 Variations in cyclothems ...... 13 Distinctive characteristics ...... 13 Types of variations ...... 14 Channel sandstones ...... 14 Lateral changes or facies ...... 14 Incompleteness of cyclothems ...... 14 Out-of-order units ...... 14 Repeated variations ...... 15 Origin of Pennsylvanian sediments ...... 15 Principles of classification ...... 17 Advantages and disadvantages of the cyclical classification ...... 18 Review of alternative classifications ...... 19 Alternative I-Individual units ...... 19 Alternative 2-Small bundles ...... 22 Alternative 3-Hemi~~clothems ...... 23 Alternative4-Cyclothems...... 23 Alternative 5-Medium bundles ...... 23 Alternative 6-Large bundles ...... 23 Alternative 7-Key beds ...... 23 Alternative 8-Entire sequence ...... 24 Conclusion ...... 24 Nomenclature of rock-stratigraphic units ...... 24 Members ...... 24 Beds ...... 25 Nomenclature of cyclothems ...... 25

PART TI .ROCK-STRATIGRAPHIC CLASSIFICATION

General Statement ...... 27 McCormick Group ...... 28 Case~villeFormation ...... 28 Lithology ...... 28 Thickness ...... 29 Members of the Caseyville Formation ...... 29 Southeastern Illinois ...... 29 Southwestern Illinois ...... 29 Abbott Formation ...... 30 Lithology ...... 30 Thickness ...... 30 Members of the Abbott Formation ...... 31 Southern Ihois ...... 31 Western Illinois ...... 31 Kewanee Group ...... 31 Spoon Formation ...... 32 Lithology ...... 32 Thickness ...... 32 Members of the Spoon Formation ...... 32 Southeastern I!!inois ...... 32 Southwestern Illinois ...... 33 Western Illinois ...... 33 Northern Illinois ...... 33 Eastern Illinois ...... 33 Carbondale Formation ...... 34 Lithology ...... 34 Thickness ...... 34 Members of the Carbondale Formation ...... 34 Southern Illinois ...... 34 Western and northern Illinois ...... 35 Eastern Illinois ...... 36 McLeansboro Group ...... 36 Modesto Formation ...... 36 Lithology ...... 36 Thickness ...... 36 Members of the Modesto Formation ...... 37 Southeastern Illinois ...... 37 Southwestern Illinois ...... 37 Western and northern Illinois ...... 38 Eastern Illinois ...... 38 Bond Formation ...... 35 Lithology ...... 38 Thickness ...... 39 Members of the Bond Formation ...... 39 Central and southwestern Illinois ...... 39 Southeastern and eastern Illinois ...... 39 Northern Illinois ...... 39 Mattoon Formation ...... 39 Lithology ...... 40 Thickness ...... 40 Members of the Mattoon Formation ...... 40 Central and southeastern Illinois ...... 40 Eastern Illinois ...... 41 Northern Tllinois ...... 41

PART 111 .CYCLICAL CLASSIFICATION

General Statement ...... 42 Name Changes ...... 42 Northern and western Illinois ...... 42 Southern Illinois ...... 42 References ...... 57 Appendix Geologic Sections: Type and reference sections of formation\ 1. Type section of Caseyville Formation ...... 61 3. Reference section of Caseyvil!e Formation ...... 61 3. Type section of Abbott Formation ...... 62 4 . Type section of Spoon Formation ...... 62 5 . Reference section of Spoon Formation ...... 63 6 . Type section of Carbondale Formation ...... 65 7 . Type section of Modesto Formation ...... 67 8 . Type section of Bond Formation ...... 70 9 . Reference section of Bond Formation ...... 73 10. Type sections of some members of the Mattoon Formation ...... 77 11. Reference section of Mattoon Formation ...... 83

ILLUSTRATIONS FIGURE PACE 1. History of stratigraphic classification of Pennsylvanian rocks used by the Illinois State Geological Survey ...... 8 7 . Arrangement of lithologic units in a cyclothem ...... 12 3 . Principal alternatives for formations in the Pennsylvanian rocks of Illinois . 20 4 . Distribution of the four principal lithologies in Pennsylvanian strata of Illinois ...26 PLATE 1. Rock-stratigraphic and cyclical classification of the Pennsylvanian strata of Illinois. 1960 ...... in pocket

TABLE PAGF: 1 . Type localities of accepted Pennsylvanian rock-stratigraphic units in stratigraphic order ...... 14 2 . Alphabetic list of named cyclothems in Illinois showing formation. distribution. and principal references ...... 52 3 . Alphabetical list of names accepted and names restricted or abandoned in this report 51

Y IAN

R. M. Kosanke, 9. A. Simon, H. R. Wanless, and H. B. Willman

ABSTRACT

A new rock-stratigraphic classification of Pennsylvanian strata of Illinois is presented in conformity with the multiple stratigraphic classification system recently adopted by the Illinois State Geological Survey. The nearly 3000 feet of Pennsylvanian strata have been classified into formations based on gross variations in average composition or in relative abundance of distinctive lithologic types. The following three groups and seven formations are recognized. Maximum thickness fft.) McLeansboro Group Mattoon Fonnation 600 + Bond Formation 300f Modesto Formation 400 Kewanee Group Carbondale Formation 400 Spoon Formation 350 McCormick Group Abbott Formation Caseyville Formation

The Pennsylvanian sequence consists of several hundred individual lithologic units- sandstone, shale, clay, limestone, and coal - few of which are thick enough to be considered formations. About 130 of the individual units have been named and are recognized as members. The gross characteristics used to differentiate the formations generally cannot be determined from individual exposures. Consequently, identification of a formation de- pends on recognition of a characteristic member within the exposure, or on determination of the relation of the exposure to selected widespread members that are the bounding units of the formations. The revised classification replaces one that did not recognize formations. In the previous classification four groups were divided into about 50 cyclothems based on the cyclical repetition of the various rock types. Because the cyclical units have not proved useful in economic studies and have not been widely used in mapping, they have not made satisfactory units for rock-stratigraphic classification. However, as they are particularly useful in geologic interpretation they are retained in a separate cyclical classification. The practice of applying the same geographic name to several closely associated members is eliminated and new names have been presented where necessary. Although an effort has been made to extend one name to all equivalent strata in various parts of the state, local names are retained in some areas. A chart shows a composite section of the Pennsylvanian strata in Illinois, all the names accepted in Illinois for the rock units and cyclothems, and correlations with units in Indiana, western Kentucky, and Missouri. Descriptions of the type sections of the formations, a table of type localities of all named members, and a list of type localities of named cyclothems are included. ART BLEM OF CLASS

INTRODUCTION Pennsylvanian rocks of Illinois, thick units Pennsylvanian strata constitute the bed- of limestone, dolomite, sandstone, and rock surface throughout approximately shale are differentiated into formational four-fifths of Illinois and have a maximum units characterized by gross lithologic fea- thickness oi: about 3000 feet. Because an tures. In contrast, the Pennsylvanian units impor tan t segment of geological research in that may be identified by similar lithologic the state is concerned with Pennsylvanian characteristics are for the most part too rocks, the design of an effective strati- thin to be accepted as iorrnational units. graphic classification of these strata has Many 01 these thin units have a greater long been of major interest to the Illinois contrast in lithology than formations in State Geological Survey. pre-Pennsylvanian rocks. Both field and The last extensive study of the classifica- subsurface stratigraphy of Pennsylvanian tion of the Pennsylvanian rocks of Illinois rocks are based largely on identification established the cyclothem as the funda- and correlation of these units, many of mental unit of rock classification (Weller, ~vhichare useful key beds. Wanless, 1927-1932) . A1 though cyclothems Consideration of these factors prompted were considered a special type of forma- the restudy of Pennsylvanian classification tional unit, the earlier formations, each by a Survey committee consisting of the including many cyclo thems, were re tainecl authors of this report. John C. Frye, Chief of the Survey, took part in the discussions until 1940, at which time they were elevated and was particularly helpful in the con- to the rank of groups. Prior to the present sideration ol the theoretical aspects of study, no further changes had been made stratigraphic classification. Raymond Siever in classification units. served on the committee until he left the The relation of the new classification Survey. David L. Reinertsen assisted in field (pl. 1) of Pennsylvanian rocks to the pre- studies of the type sections and was pri- vious classifications used by the Illinois marily responsible for assembling data arid Geological Survey is shown in figure 1. The for compilation of tables of stratigraphic development of earlier classifications has names. He also assisted in compiling the been discussed in a 1956 publication by type and reference sections in the appendix. Wanless. The same publication contains Other members 01 the Survey staff were a chart compiled by Raymond Siever show- consulted on specific problems. The fol- ing the classification and nomenclature in lowing gave helpful criticism of the manu- effect at the beginning of the present study. script: Elwood Atherton, A. H. Bell, K. E. Recognition of the cyclical sequence as a Clegg, George E. Ekblaw, J. E. Lamar, unit of stratigraphic classification has been G. B. Maxey, D. L. Reinertsen, D. H. instrumental in promoting advances in Swann, TAT. H. Smith, M. L. Thompson, Pennsylvanian stratigraphy, and the unit TV. A. White, and G. M. Wilson. has been accepted in many quarters. How- Stratigraphic classifications are essential- ever, it has not been used extensively in ly philosophical, expressing as they do in- economic studies, particularly coal and oil clividual concepts ol the nature and origin studies primarily concerned with subsur- of the rocks and of the objectives and mode face data. of operation of classification. Complete Furthermore, the Pennsylvanian classifi- agreement on these factors is scarcely to be cation has developed along lines diverging expected, even from a committee of four. from the stanclard practice used for other However, this committee started with gen- systems of rocks. This divergence reflects eral agreement on the need for improve- the major differences in the character of ment of classification and nomenclature the stratigraphic sequences. In the pre- and belief that a completely new analysis NATURE OF PENNSYLVANIAN STRATA 11 oS the problem would be worth while. Northern Illinois-Cady (1915, 1919) , The conclusions reached represent in major Culver (1922) , Willman and Payne part a general agreement rather than a (1942) . compromise oT conflicting viewpoints. Central Illinois - Shaw and Savage The restudy consisted of the following (1913) , Kay (1915) , Udden and Shaw stages : (1915), Shaw (1921, 1923), Lee 1) Review of the nature of Pennsylva- (1926) , DuBois (195 1) , Ball (1952) , nian sediments based on consideration of Smith (1958) . specific sequences, generalizations, and types Eastern Illinois-Campbell and Leverett of variations. (1900), Kay and White (1915), Rich 2) Discussion of the origin of the sedi- (1916a, 1916b), Cady and others (1952), ments and the basic problems in sedimenta- Potter (1956). tion to provide a basis for recognizing Southern Illinois - Shaw and Savage natural units and evaluating their relative (1912), Cady (1916, 1917, 1919, 1925)) importance. Lamar (1925) , Butts (1925) , Weller 3) Discussion of principles of strati- (1940) , Harrison (1951) , Cady and graphic classification. others (1952, 1955) , Wanless (1955) , 4) Critical review of the existing classi- Smith (1957) , Hopkins (1958) . fication. 5) Evaluation of alternative classifica- GENERALCHARACTER tions. In general, 85 to 95 percent of the sedi- 6) Definition of new stratigraphic units ments of Pennsylvanian age in Illinois are and revision of nomenclature. siliceous clastics. About 50 percent are predominantly argillaceous rocks (47 per- NATURE OF PENNSYLVANIAN cent gray, red, green, and black relatively STRATA soft shales, 2 percent underclays, and 1 percent black slaty shales), and about 40 Stratigraphic classifications are based on percent are arenaceous rocks (sandstones generalizations of the nature of the sequence and siltstones). About 5 percent of the and are effective to the degree that the sediments are predominantly calcareous generalizations accurately embrace the rocks, largely limestone but inclucling some range of variations. Consideration there- dolomitic and ankeritic types. One to 2 fore has been given to both the general percent are coal, and all other types, in- nature of the sequence and the types of cluding siderite and chert, make up less variations. than 1 percent of the total. The lithologic sequence of Pennsylvanian rocks is well known throughout much of THICKNESS OF UNITS Illinois. Detailed studies have been made The sequence is characterized vertically in many areas and inter-area correlations by frequent and commonly sharp changes are well established (Wanless, 1956) . The in lithology. These changes differentiate exact correlation of certain isolated ex- units of uniform lithology, referred to as posures, however, is not yet definite, par- "individual units." Five hundred or more ticularly in the lowest and highest parts individual units are present, most of them of the column. from less than an inch to perhaps 30 feet The nature of the sequence is shown in thick. Only a few locally exceed 100 feet a composite section for the whole state thick, and the average thickness is per- (pl. 1). Details of typical sections may be haps on the order of 3 to 5 feet. obtained from published reports, partic- The sandstones, many of which are inter- ularly the following: bedded with siltstone and grade laterally Western Illinois-Udden (1912), Hinds to siltstone, are the most variable in thick- (1919), Cady (1921), Savage (1921), ness. Thicknesses of 30 to 50 feet are com- Culver (1 925) , Wanless (1929, 1931a, mon. A few sandstones are as much as 100 193lb, 19Slc, 1957). feet thick in some areas and rarely they are ILLINOIS STATE GEOLOGICAL SURVEY R. 1. 214

Shale, gray, sandy at top; contains marine fossils and ironstone concretions, especially in lower part.

Limes tone; contains marine fossils. Shale, black, hard, fissile, "slaty"; conta ns large black spheroidal concretions and marine fossils. Limes tone; contains marine fossils. Shale, gray; pyritic nodules and ironstcme concretions common at base; plant fossils locally common at base; marine fossils rare.

Coal; locally contains clay or shale partings.

Underclay, mostly medium to light gray except dark gray at top; upper part noncalcareous, lower part calcareous. Limestone, argillaceous; occurs in nodules or cliscontinuous beds; usually nonfossiliferous. Shale, gray, sandy.

Sandstone, fine-grained, micaceous; and sil tstone, argillaceous; variable from massive to thin-bedded; usually with an uneven lower surface.

Fig. 2.-Arrangement of lithologic units in a cyclothem. NATURE OF PENNSYLVANIAN STRATA 13

300 or more feet thick. Some of the un- ponents of the sequence are a basal sand- usually thick occurrences probably repre- stone overlain by underclay, coal, black sent two or more superimposed sandstones. slaty shale, limestone, and gray shale. In Uninterrupted sequences of shale in addition, a limestone bed is locally present places exceed 100 feet thick, but thick- in or at the base of the underclay and an- nesses of 20 to 40 feet are more common. other beneath the black slaty shale. Gray The shales are much more persistent than shale is locally present between the sand- the sandstones and their variations in thick- stone and underclay and between the coal ness generally are gradual, except where and the black slaty shale. This sequence they are truncated by sandstones. represents a cycle of sedimentation (Udden, The underclays are commonly 2 to 3 feet 1912) and is currently called a cyclothem thick, but greater thicknesses are not rare (fig. 2) . About 50 cyclothems are named and locally they are as much as 30 feet in Illinois. thick. The black slaty shales are commonly 1 to 5 feet thick but are thicker in some The lateral uniformity of the cyclothems areas. and their vertical similarity both have been The limestones have a wide range of emphasized in many reports. In practice, thickness. Many widely persistent beds correlation is based on persistent differences are less than a foot thick, and thick- in cyclical sequences and on distinctive char- nesses of 2 to 4 feet are common. A few acteristics of individual beds. limestones are persistently 10 to 20 feet thick; in limited areas some are as much as DISTINCTIVE CHARACTERISTICS 30 feet thick, and one limestone has a maxi- The limestones have perhaps the greatest mum thickness of 50 feet. distinctiveness and some may be identified Most coal beds are 6 inches to 3 feet by characteristic texture, argillaceous con- thick, but they range from scarcely more tent, bedding, color, weathering character, than a thin carbonaceous streak to beds or faunal assemblage. However, because as much as 15 leet thick. A few coal beds most of the limestone lithologies are re- average 3 to 7 feet thick over broad areas. peated somewhere in the column, specific identification of many limestones must be PERSISTENCE OF UNITS based in part on knowledge of the sequence Most of the Pennsylvanian sequence is or or approximate position in the column. characterized by great lateral persistence of Some of the black slaty shales are nearly almost all individual units except the sancl- as distinctive as the limestones and may be stones, a few of which likewise have good identified by variations in hardness, fissile continuity. Some of these lithologic unj ts character, and content of fossils and con- appear to be almost continuously present cre tions. throughout Illinois. All gradations of per- Some shales are distinctive in color, tex- (;istence may be found, from beds that are ture, bedding, and content of fossils and erratic in occurrence to those that extend concretions. almost continuously over many counties with only slight variations in thickness. The sands tones locally have distinctive The latter include many thin beds, some texture, degree of cementation, or weather- only an inch or two thick. ing characteristics. A few coals have distinctive clay or shale CYCLICAL SEQUENCES partings, and a uniform thickness of the The individual units generally occur in coal may be characteris tic throughout some orderly sequences that are repeated many regions. times. The sequences are rarely complete, Even the underclays vary in color and but exceptions to the order are not com- commonly have an upper noncalcareous mon. The most commonly present com- zone that may have a distinctive thickness. ILLINOIS STATE GEOLOGICAL SURVEY R. I. 214

TYPES OF VARIATIONS and the adjacent shale that forms the upper- Variations in the sequence of beds are most unit of the underlying sequence make of two general types-those resulting from it difficult to interpret stratigraphic bound- cutouts and unconformities and those re- aries in many areas. Except where the sand- sulting from varying conditions of sedi- stone is in channel facies, it is dimcult to mentation, mainly modifications of the determine whether sandstones, siltstones, usual cyclic pattern. The latter type in- and sandy shales are interchannel facies of cludes 1) lateral changes or facies, 2) the the sandstone or are sandy facies of the components of the sequence, 3) the inter- shales that are cut out along the channels. calation in the sequence of individual com- Many of the sandstones grade laterally to ponents out of the usual order, and 4) siltstone, and sandy shale locally replaces variations repeated in several cyclical se- the sandstone, even in the channel facies. quences, thus producing different types of Where outcrops are abundant it is com- cycles. monly possible to see the channel margins and thus determine the relations of the Channel Sandstones sandy deposits. In the much larger area In many places variations in sequence where Pennsylvanian stratigraphy is based result from truncation of underlying beds entirely on subsurface studies - electric by channels filled with sandstone. Many logs, sample cuttings, a few cores - recog- channels cut through the upper units of nition of the unconformity is much more the underlying cyclothem and over con- difficult. Sandy beds may be arbitrarily siderable areas rest directly on the coal. assigned to the upper cyclothem, but the Some sands tone bodies cut through the relations are clear only when the sandstones coals and deep into the underlying strata. are in the most prominent channel facies. The generally massive and relatively coarse- grained sandstones of the channel facies Incompleteness of Cyclothems have a sharp and undulating basal con- The relative cornpleteness of cyclothems tact that appears to give the cyclical se- in four quadrangles in western Illinois has quences an unconformable base. However, been determined by Wanless (1957, p. 55) . the frequency of channeling is relatively In 23 cyclothems present in that area, the low. Drill records show that throughout average cyclothem has only 5 of the 10 most much of Illinois only two or three of the common units of the ideal cyclothem. sandstones are likely to occur in a prom- Although one cyclothem has nine and four inent channel facies at one place. The have eight units, many units are known number in any one drill hole generally will from only a few localities. Including known average less than one per 10 cycles. occurrences elsewhere in the Illinois Basin, Although the channels commonly are the average completeness is about 7.5 of believed to be the result sf subaerial ero- the 10 units for these 23 cyclothems, and sion, the sequence between the channels all 10 are known for four cyclothems. Be- appears to be entirely conformable. The cause of the local distribution of many physical evidence for unconf ormi ties ap- units, the completeness of the cyclothems pears to be present in less than 20 percent decreases with restriction of area. In any of the area for any cyclothem in Illinois, one locality, such as a drill hole, the com- and no unconformities are known for some pleteness commonly will be less than half cyclothems. An exception is the limited of the standard units. area in extreme southern Illinois where the Caseyville sandstones may occur persistent- Out-of-Order Units 137 in channel facies. Variations in the sequence also result from the intercalation of units out of the Lateral Changes or Facies standard order. An example is the presence Lateral changes in texture of both the of a local 4- to 6-inch coal in the Canton basal sandstone of one cyclical sequence Shale of the St. David Cyclothem in north- ORIGIN 01; PENNSYLVANIAN SEDIMENTS 15 ern Illinois. The Jake Creek Sandstone to be a valuable aid in the differentiation that locally underlies the Oak Grove Lime- of natural units, the formulation of rock- stone Member of the Liverpool Cyclothem stratigraphic classification cannot wait for in western Illinois also is an out-of-order the solution of such problems. It has bed. In northern Illinois an underclay and seemed imperative to proceed with refine- coal are present between this sandstone and ment of the classification, anticipating that limestone and the sequence is differentiated more effective field stratigraphy will fur- as the Lowell Cyclothem. Thus, the Oak ther the understanding of sources of sedi- Grove Limestone and the overlying Puring- ments, mode of transportation, and cause ton Shale are in the Liverpool Cyclothem and environment of deposition. The major of western Illinois hut are in the Lowell concepts of origin are briefly reviewed, Cyclo them in northern Illinois. Classification of Pennsylvanian rocks was These relations illustrate the potential hampered for many years by the concept variations in sequence resulting lrom lateral that the sediments were laid down irreg- persistence of only one or two units of a ularly and that, except for some of the coals cyclothem and suggest that a cycle can be and a few other beds, lenticular relations interrupted at almost any point and started and facies changes so dominated the sedi- over again. This typc of variation could ments that local sequences had little sig- produce a complete lack of orderly se- nificance. Recognition of the widespread quence, but it appears to be so uncommon distribution of many units and the cyclical that it can be recognized and treated as a nature of the sedimentation was a major local aberration of a cyclothem unless it stimulus to studies of origin. is prominent enough to justify recognition The variety of sediments found in the as a separate cyclothem. Pennsylvanian rocks suggests a wide range in conditions of sedimentation. Compared Repeated Varia tiom with the sediments of other Paleozoic sys- Some variations from the standard se- tems, they indicate both a greater range in quence are repeated through several cycles environment and more frequent changes and provide a basis for recognizing types in type of sediment. of cyclothems. Three major types of varia- Explanations for the cyclical character tions may be noted: 1) those characterized of the sedimentation hinge on the origin by excessive development of one of the of the individual lithologic types, but only standard members, such as a sandstone or a few of these have a reasonably clear origin. limestone, 2) those characterized by the The environment of deposition of the lime- persistent dropping of a standard member, stones and associated shales is clearly marine common cases being the persistent absence because they contain marine fossils. Varia- of the sandstone, limestone, or coal, and tions in the fossil assemblages of the lime- 3) those resulting from the presence of new stones are taken to reflect differences in units, such as red shale. water depth (Elias, 1937; Wanless, 19.58). Some of these variations modify the com- It is generally accepted that the coals plexion of the entire sequence, producing were formed from plant debris that accum- sections dominated by shale or sandstone, ulated essentially at place of growth in or in some areas permitting a vertical dif- freshwater swamps. A few local coals repre- ferentiation bawl on changes in types of sent accumulation of transported plant cyclotherns or on types of distinctive units. debris. The remainder of the sediments are of OliTGIN OF PENNSYLVANIAN less clear origin. Most of the sandstones SEDIMENTS are commonly accepted to be nonmarine, as Many aspects of the origin of Pennsyl- suggested by the local presence of thin coals vanian sediments remain controversial. and the common occurrence of plant fossils. Although an understanding ol the mode of However, a Eew sandstones locally contain tleposition of the sediments is recognized indigenous marine fossils. Also, the uni- 16 ILLINOIS STATE GEOLOGICAL SURVEY R, I. 214 form texture, sorting, and bedding through- Several explanations have been suggested out considerable thicknesses of sandstone for the cyclical alternation of marine and suggest marine sedimentation rather than nonmarine sediments. All accept the re- stream deposition. quirement of a sinking basin, but some en- The origin of the channels which the vision essentially continuous or repeated sandstone fills likewise is uncertain. Some sinking, and others postulate alternating geologists see in them a dendritic pattern sinking and uplift. Changes in the types of subaerial erosion, in which case the of sediments of the individual units are filling with nonmarine deposits is a logical, attributed by some to repeated diastl-o- although not essential, consequence. O ther phism in the positive areas. Others favor students of the problem consider the chan- climatic cycles as the major control in nels to be marine or tidal-flat scour fea- erosion and transportion of clastic sedi- tures, in which case the sandstones could ments. Eustatic changes in sea level have have been deposited in a marine or brackish been proposed as the dominant factor in water environment. As the general uni- controlling the type of sediment. Some formity of the sandstones seems inconsistent favor cycles of glaciation as the cause of with the steep-sided channels, it is not im- e~xstatic changes. An evaluation of thesc possible that some are subaerial channels concepts is beyond the scope of the pres- filled with marine sands. ent study. The sands deposited in a non~narineen- The individual units of a cycle are con- vironment in some regions may grade sic-terecl to be essentially contemporaneous through brackish water to marine deposits. throughout the areas in which they can be Variations in relative subsidence ol' the traced. In general, lateral variations in basin could cause some of the sandstones lithology of the members are within a in any region to be nonmarine and others limited range hat does not overlap the to be marine. The principal source of the range of variations oS adjacent units. The sandstones appears to he the Canadian widespread continuity of many of the litho- Shield northeast of Illinois. Some additions logic units without recognized lateral tran- probably came into southem Illinois from sition mnes opposes a concept of facies rela- the east and into northern and western tionships be tween members. Illinois from the northwest (Siever and Because each cycle contains both marine Potter, 1956; Potter ancl Siever, 1956a, ancl freshwater deposits, marine invasion 1956b) . and withdrawal is required for each cycle. The general absence of fossils iavors a JE the regional continuity of individual nonmarine or brackish water origin for the cycles is accepted, the amount of time trans- limestones associated with the underclays. gression of individual units cannot exceed Some of these limestones have a few fossils the duration of each marine invasion or, that are not typically marine. Marine fos- similarly, of each nonmarine sequence. sils have been found locally in limestones Minor overlapping time equivalence be- at or near the positions of the underclay tween different lithologies is required to limes tones. explain the irregular distribution of some It is widely accepted that the sandstone- units. For practical purposes, however, the underclay-coal sequence in each cyclothem bedding contacts be tween lithologic units is nonmarine, whereas the shale-limestone appear to be isochronous surfaces. sequence above the coal is marine. How- This interpretation applies only to areas ever, most of the exceptions noted above such as the Illinois Basin where alternating indicate a trend toward accepting as marine some of the beds supposed to be nonmarine, marine and nonmarine sequences are widely and it is not impossible that more of the se- traced. It may not apply to areas where the quence is marine or brackish water than is sequence is almost entirely marine or non- now accepted. The freshwater origin of the marine. In areas where the sequence is clom- coal beds limits the trend in that direction. inantlv nonmarine sandstone, conditions PRIATCIl'LES 01; CLASSIFICA TlOhT 17 probably f avorecl sand accunlulation during coarse subclivision, ease 01 difterentiation, most ol the cycle, rather than periocls 01 ancl mappability must weigh heavily in nondeposi tion (equivalent to the marine making the choice. sequence elsewhere) betwccn the intervals 3) The adoption 01 uniform use 01 ol sand accumulation. Similarly, in the standarcl units of rock-stratigraphic classi- nlarinc sequences, sedimentation probably fica tion throughout the stratigraphic col- Tvas nearly continuous rather than inter- umn. X major problem in the lormulation I upted by cliastenls equivalent to the inter- ol policy was whether different classifica- Ials ol nonmarine deposition ol other areas. tion names should be clcvised to emphasix tlifterences in character of units in diflerent PRINCIPLES OF CLXSSlFICXTION systems or parts 01 systems, a notable ex- ample being the cyclothems oS the Penn- One object of the present restudy of sylvanian System. It was decided that such Pennsylvanian classification was to moclily practice had no stopping point and that it the existing classification to conform to the ~iolateda major objective of classification recent statement of policy of the Illinois -the design of a uniform framework fo1- State Geological Survey regarding strati- evaluation of units. This decision removes graphic nomenclature (\\Tillman, Swann the name "cyclothem" from the rock-strati- and Frye, 1958) . That policy statement graphic classification of the Illinois Geolog- introcluced se~eralconcep t5 that hael not ical Survey, although it does not eliminate been accepted when the last major review the cyclical unit from possible recognition 01 Pennsylvanian classification was made, as a group, formation, or member. pi-titularly the following: 1) The use of multiple classification to 4) The acceptance of the formation as develop stratigraphic classifications kor the funclamental unit of rock-stratigraphic special needs ancl to restrict the range of classification. For some years the illinois criteria employed in a single classification. classification has included groups, cyclo- Under this policy, cyclical sedimentation thems, and members, but no formations. can be accepted as a basis lor 5tratigraphic The funclamental unit is interpreted in classification independent of rock-s tra ti- the new policy to be the first unit to be graphic classification, although the policy clifferentiatecl, the one unit that most clear- allows the use of cyclical sequences as rock- 1y meets, or most effectively compromises, stratigraphic units where more desirable the requirements of distinctive lithology, units are not present. Rock-stratigraphic continuity, and practical needs, and the units are baseel on lithologic difterences one unit of which a complete sequence is between adjoining units; cyclical units arc required. Other rock-stratigraphic units based on similarities between units. Therc- are assemblages or subclivisions 01 Sorma- Sore, cyclical classification is retained lor tions, usecl only as needed. This intei-pre- its special merits, unencu~nberetlby the re- tation establishes a definite method ol: ap- quirements of rock-stratigraphic classifica- proach to classification, primarily aimed at tion. more consistelit differentiatioil of units. 2) The acceptance of rock-s tra tigraphic 5) The clarification of policy concerning classification as the major working classi- priority. The accepted rules eliminate du- fication rlsecl by the field ant1 subsurface plicate use 01 names, a practice widely usecl stra tigi-apher. Such acceptance requires that in the Pennsylvanian to show close associa- rock-sti-a tigraphic classification be designed tion ancl to conserve names - for exainplc. to meet practical needs. Ho~dre\.ei-,a classifi- Curlew Limestone, Curlew Coal, Curlew cation that does not recogni~egenetic units Sandstone. Some attempt has been maclc is not likely to be the most effective. In to correct conflicts resulting from the clis- most sequences, and particularly in the cowry of prior use of a name, but the new Pennsylvanian, several possible units may policy accepts the premise that in cases ol qualify as forinations, ancl practical con- long established use a change in names may siderations such as the need for fine or cause confusion where no confusion has ex- 18 IlJ,ih'O/S S TATE GEOLOGICAL S URVEI' It. I. 2 I-/ istecl and none is likely to develop. This ant1 in indicating tllc degree and area of premise reduces the number of names which tl-uncation oL underlying strata. need to be changecl. 3) Cyclotlmns can be dilterentiated in 6) The definition of rock-stratigraphic cores, and evcn in some cle5criptions ol units should include gross lithology, strati- cores made beiore the cyclical arrangement graphic position in relation to overlying was recogni~ed. Unclci- the most fa\ orable and underlying beds, type 5ectioi1, ancl condition5 they also ma) be diltei-entiatetl tlerivation of name. Many of the named i n 5;iinples of cuttings J ronl churn ancl stratigraphic units in the Pennsylvanian ol rotary drill holes, in some cases with an Illinois do not have adequate definition5. accuracy as great as that Ior nm5t f omla- Some names that were introducecl on maps tions in other system,. Ho~vevei-,they arc or in tables have been wiclely used. In some differen tiatetl in subsurf ace ~vith much less cases, although not generally so stated, the accuracy in areas ol thin c-yclothems and impression is given that the names are in- in areas where the sanclstones are not well troduced informally, and therefore neither tlevelolxcl. In nluch of Illinois they are standard practices of definition nor regard recogni~eclreadily from subsurface data in for priority need be followecl. The new parts of thc scction, scarcely at all in other policy calls for introduction of names only parts. in places where adequate definition can be 4) Cyclothems have great lateral con- given. If a change in previou5 classification tinuity and thus are valuable f-or correla- is involved, a statement of reasons for the tion. The cyclothem unit extends and can change must be given. be recogni~ecl more widely than an in- cliviclual member. In view, however, of the ADVANTAGES AND DISADVANTAGES great continuity of many distinctive mem- OF THE CYCLICAL CLASSIFICATION bers, this aclvantagc is only locally sig- nificant. Since the cyclothem was introclucecl as 5) Lateral variations in clominant com- a unit of classification in the Pennsylvanian position within cyclothems anel vertical rocks ol' Illinois, inany advantages in its cliii'erences in sequence ancl lithology be- use have become evident, among them the tween cyclothems provide a valuablc ap- following: proach to studies of environment, seclimen- 1) Recognition oS the cyclical nature oS tation, source ol sediments, anel other the sediments has been v;iluable in solving aspccts ol' genesis. field problems, particularly in deciphering Dificultie5 encountered in the use of the poorly exposed sections, in directing the cyclothem as the funclamcntal unit of rock- search for important coal and limestone str:~tigraphic classification include the fol- key beds, and in providing a framework lowing: fos systematic field description. 1 ) Differentiation oC the Pennsylvanian 2) Cyclotl~einsha~e been shown to bc scclt~enwbased entirely on the base ol the mappable on thc scale ol' a mile to the inch sandstones, oi- on thc position of the sand- (MTillnian ancl Paync, 1942; Mianless, 1957) , stones whei-c they are absent, has provecl providing that some thin or partial cyclo- difficult in man). areas. Although the base theins nay be combinecl in a map unit. ol the 5anclstones is sharply defined where This practicc does not differ lrom that the sandstonc is in channel lacies, the con- conirnonly usecl where certain formations tact is gradational in the areas between the thin to unmappable six, but it may be channels. Because the upper shale of the required more trequentl~. in mapping un clei-lying cyclo them generally becomes cyclothems. X f-ew persistently thin cyclo- sand) upwarcl, the contact is difficult to theins are not known to be of mappable place. It is impossible to be certain that thickness. Mapping cyclothems is essential- sandy beds between the channels are con- ly mapping the base of the sandstones. This tinuous with the sancistone in the channel has advantages lo call?^ in outlining cutouts facies. In many cases sandstonc .is absent. ALTERNA TIVE CLASSIFICATIONS 19

Channel facies have proved to be much less used uniformly throughout the rock extensive than originally believed and the column eliminates the use of the name advantages in mapping them, therefore, cyclothem. It requires recognition of are very limited areally. As a whole, the a complete sequence of formations, base of the sandstones is the most difficult and, to date, it has not been practical contact in the entire sequence to pick con- to differentiate a complete sequence sistently. of cyclothems in the lower and upper 2) In mapping, the bases of the sand- parts of the column. stones have the disadvantage of being the The general principle that formations least useful horizons for showing structure. are differentiated by differences in This disadvantage is partially offset by the lithology is not consistent with the useSulness of the contact in outlining cut- recognition of cyclothems as forma- outs, as previously noted. In field work, tions, because cyclothems are similar. mapping the base of the sandstones is rela- A1 though cyclo thems are lithologic tively difficult and time-consuming. The units, the emphasis in their recogni- contact is also perhaps the least economical- tion is on sedimentation and genesis ly significant, and except on very large scale rather than lithology, and in some maps its mapping is generally impractical ways they are more closely related to if one or more of the commercially im- time-stratigraphic than to rock-strati- portant coals, limestones, shales, and under- graphic units. clays is shown. Although not all of these Cyclothems have been considered ex- can always be mapped, mapping either the empt from rules of nomenclature. The underclay, coal, or limestone of a cyclothem common disregard of rules of priority provides adequate location for the other and definition makes necessary a com- units of the cyclothem, because they are plete re-evaluation of their classifica- close in the sequence. As location of min- tion and nomenclature. eral resources is a major objective of Consideration of the advantages and dis- geologic mapping, it has become increasing- advantages of the cyclical classification has ly important to map the economic beds, if led us to conclude that the cyclical sequence necessary at the expense of mapping forma- has important uses and should be retained tion or other boundaries. in a cyclical classification independent of the rock-stratigraphic classification. 3) A similar problem arises in the dif- ferentiation ol cyclothems in subsurface - in cores, cuttings, and electric logs. In the REVIEW OF ALTERNATIVE analysis of the large amount of data avail- CLASSIFICATIONS able from drilling for coal, oil and gas, and The major and long-standing problem of water in the Pennsylvanian, the differentia- rock-stratigraphic classification in the Penn- tion of cyclothems requires recognition of sylvanian successi~nis the recognition of a the base of the sandstones, the contact most formational unit. The principal alterna- difficult to pick. As other contacts may be tives for formational units that have been readily identified, cyclothems usually have considered in this restudy are summarized not been differentiated, even where the data in figure 3. There are a few possibilities were adequate to permit their recognition. intermediate to those illustrated, and some In general, cyclothems have not proved to boundaries could be moved without sig- be of sufficient value in economic studies nificantly changing the degree of subdivi- to justify the additional work of differ- sion or the principle involved. entiating them. 4) Other difficulties with the cyclical classification arise from changes in strati- The many individual rock units that graphic policy, including the following: compose the Pennsylvanian sequence have a) The requirement that units of rock- been called members, beds, or units. They stratigraphic classification should be are, in general, the 10 lithologic units of TYPICAL I 2 3 4 SEQUENCE INDIVIDUAL SMALL iEMICYCLICAL CYCLICAL UNIT UN IT ( 1502 rt.) UNITS BUNDLES

Sandstone Dominantly Nonmarine sandstone

Sandy shale

Gray shale Marine Limestone Block slaty Other lithologies shale I Coal Underclay

Siltstone Nonmarine

Dominantly sandstone

Calcareous shale Marine

Cyclathem

Nonmarine

"~reshwater" or underclay Other lithologies limestone I

Marine

Cyclothem

Nonmarine Dominantly sandstone

Fig. 3. - Principal alternatives for formations 5 6 MEDIUM LARGE COLUMN KEY BEDS ( 2500f ft ) BUNDLES BUNDLES

Mattoon Fm.

Bond Fm.

Modesto Fm.

Carbondale Fm.

Kewanee Gr.

Spoon Fm.

Abbott Fm.

McCormick Gr.

Caseyville fm.

in the Pennsylvanian rocks of Illinois. ILLlhTOIS STATE GEOLOGICAL SURVEY R. 1. 214 the typical cyclothem, but twice as many tions that contain the coals, limestones, or more may be identified in some cyclo- and thin sandstones. Alternative 2 recog- thems depending on the degree of splitting. nizes the dominance of shale and sandstone These individual units have the lithologic in the Pennsylvanian sequence. clis tinctiveness and continuity desired in In certain areas of Illinois and in certain formations to a degree generally exceeding parts of the column, this method of classi- that found in other Paleozoic systems in fication proves workable. Applied to the this region. Many of them are key beds on entire column it would recognize a mini- which local stratigraphic work ancl regional mum of 25 formations or perhaps as many tl-acing in the Pennsylvanian is based. as 100 formations. In spite of the factors that favor recogni- In principle ancl in degree of subdivision, tion of the individual units as formations, the small bundles offer one of the most we have found no published support for attractive means of differentiating forma- this position. The major objection to alter- tional units. 1t is used extensively in the native 1 is that it would create such a large Midcontinent region. In practice it has number of formations. Even granting some many disadvantages for use in Illinois, as lumping of closely related beds and of in- follows: terbedded units, at least 300 formations, 1) It results almost entirely in differ- and perhaps several hundred more, could entiating formations on the top and bottom be differentiated in Illinois. Perhaps only of the sandstones, the two most difficult a tenth of these units, mostly shales and contacts in the entire sequence to trace sandstones, would meet the recommendecl laterally. Specific identification of sand- minimum size for formations - 10 feet stones is therefore based largely on relation thick for an extent of 50 miles. Even this to beds more easily identified. size limit is too small if it results in recogni- 2) The sanclstone units are thick and tion of several thin formations in sequence, well defined only in the limited areas of the a condition that would occur many times in channel facies. Although these sandstones the Pennsylvanian. could continue to be recognized as forma- Recognition ol the formation as the fun- tions in the areas between channels where damental unit of rock-stratigraphic classi- they are thin, other unnamed sandstones in fication requires a complete sequence 01 the same sequence that are not ranked as formations. A prohibitive number would formations might be more prominent. Thus be required if individual units were ac- the ranking of units in one sequence would cepted as formations. At present there is soon be entirely out of proportion in an no demonstrated neecl for such a fine sub- adjoining area. Much of the usefulness of division, and most of the names would have the classification would be lost, and many slight use. It is conceivable that, as the unwieldy combinations, hyphenated names, neecl for greater detail in stratigraphic or new names, would be required. studies develops, such a classification will 3) The shale formations would contain be accepted. Many of these units will be the important key beds and the economical- named as their value becomes apparent, and ly important members, but their boundaries their upgrading to formational status will woulcl have no significant relations to these be less difficult than at present. important members. The formations, then, woulcl have no particular value for descrip- tive purposes in economic studies. Small bundles (fig. 3) are based on litho- 4) In parts ol the column the f~~~nations logic grouping by major rock types. Beds would be roughly equivalent to hemicycles of different rock type that are too thin to in size, but in others they would combine merit differentiation are arbitrarily in- several cycles. In general these units would cluded in the bundles. This approach be sufficiently near the cyclothem in size recognizes as formations the major sand- that their only advantage would be in elim- stones separated by dominantly shale forma- inating the restrictions imposed by rigid ALTERNATI YE CLASSIFICA TIONS 23 adherence to cyclical differentiation. A ogy and in part on differing characteristics subdivision at about this level would be of the minor constituents, particularly on more effectively served by cycles or hemi- number and thickness of distinctive beds cycles, which furnish a more systematic such as limestones and coals. The advant- basis for differentiation. ages in using these units as formations are The small bundles appear to be too as follows: heterogeneous to provide a useful system of 1) Successive units differ in gross litho- classification in Illinois. logic characteristics. 2) The units extend over much of Illi- nois. The marine and nonmarine parts of the 3) They are desirable map units. cyclothem may be treated as separate units 4) The contacts are based on widely called hemicyclothems (fig. 3) . The use traced key beds. of hemicyclothems as formations presents the same general difficulties as those pre- 5) The number of units differentiated viously noted for cyclothems. Although (seven) is not excessive. In the Pennsyl- adjacent formations would differ in com- vanian rocks of Illinois, a relatively large position, each would embody such varied Cormation has many merits. As previously rock types that the basis for differentiation emphasized, stratigraphic work will con- would clearly be genetic rather than rock tinue to be based essentially on individual stratigraphic. They would provide twice 1i thologic units regardless of how they are as many formations as the cyclothems, many classified or whatever other units are dif- of which are already too small for con- ferentiated. venient use. 6) The medium bundle is the smallest unit, larger than the individual unit, that is needed for most uses of classification. When complete description of the sequence The advantages and disadvantages of within the medium bundles is needed, using cyclothems as formations have been cyclothems or other units also may be discussed. The effectiveness of cyclothems differentiated. as formations would have been improved if a more generous lumping of thin and par- tial cyclothems had been practiced. Some of the practical objections to cyclothems The large bundles (fig. 3) are similar to would be removed if the break were made the medium bundles but are based on even at the coals rather than at the base of the more gross lithologic characteristics. They sandstones. However, even iT the base were are much larger than desired for forma- changed to this or other positions, the tional units; only three are recognized in cyclothem still would not fill either tho the entire column. Acceptance of the me- theoretical or the practical requirements dium bundles as formational units would for a rock-stratigraphic unit. As the cyclo- make these larger units logical groups. them is useful in its present form for cyclical classification and has long been established in an extensive literature in By differentiating formations strictly on Illinois, modification does not seem desir- the basis of key beds, it is possible to select able. formations of almost any size desired. How- ever, failure of this alternative to recognix internal characteristics of the units pro- The units next larger than cyclothems duces essentially artificial groupings useful are medium-sized bundles (fig. 3) diff el-- only as "pigeon holes" in classification. It, crltiated on the basis of gross lithology. therefore, falls short of many of the objec- They are based in part on dominant lithol- tives of rock-stratigraphic classification. 24 ILLINOIS STATE GEOLOGICAL SURVEY R. 1. 214

of coals, limestones, or sandstones in the An extreme method of classification, clay will be classified as beds in the area based on the general uniformity in se- where the Cheltenham Clay is recognized quence, or uniformity in heterogeneity, as a member, even though they may be would justify classification of the entire specifically iden tifiecl as members in another Pennsylvanian column as one formation. area. The expression "underclay of No. 5 Coal" should be treated as a descriptive term and For rock-stratigraphic classification the as neither a formal nor informal name. medium-sized bundles are accepted as for- The word "underclay" therefore should not mations, the individual units as members, be capitalized. Informal names, such as and the large bundles as groups. "blue band," "septarian limestone," "Car- Cyclothems are retained for cyclical clas- diomorpha limestone," should be enclosed sification. in quotation marks, but the use of such names is discouraged. In general, an in- NOMENCLATURE OF ROCK- formal name should be used only when STRATIGRAPHIC UNITS needed for local or temporary identifica- tion. If it must be used more extensively, The differentiation and naming of mem- the unit qualifies for formal naming. Geo- bers and beds requires special consideration. graphic names are not assigned to informal In the Pennsylvanian, members generally units. are distinguished by the fact that the over- The recognition of a cornplete sequence lying and underlying units are of different of members may be desirable when a de- lithology, for example, underclay, coal, and tailed description of an area is made (Will- black shale members in sequence. Beds, as man and Payne, 1942; Wanless, 1957) . The stratigraphic units, are subdivisions of mem- members can be numbered instead of bers and therefore usually have similar named, but the numbers should be used in material above and below, for example, a only the one report. In reports describing persistent clay bed in a coal member. Pennsylvanian sequences in less detail, per- haps indicating only important coals or limestones, it is not necessary to recognize Members are the primary subdivisions a complete sequence of members or even of formations. In Illinois they consist of all the named members. 1) distinct lithologic units such as sancl- stones, shales, coals, slates, underclays, lime- Excessive splitting of members based on stones, and 2) alternations of two (rarely a1 ternating units of similar lithology (inter- more) distinct lithologic types, such as in- bedded limestone and shale) or on minor terbedded limestone and shale. Previously lithologic differences should be avoided. in this report members have been referred Transitional zones should not be differ- to as individual units. entiated as members but should be included Only those members that are referred to in the member above or below. frequently should be named. Additional Minor variations in sand, shale, or cal- names may be added as the need is demon- careous content, of limestone or ironstone strated. Members that can be identified concretions, of lenses of sandstone, or of easily by reference to another member, as other inclusions pesent in part of a mem- underclay of No. 5 Coal, black shale above ber do not justify differentiation of that No. 5 Coal, underclay limestone below No. part as a separate member. These varia- 5 Coal, need not be named. Unusual rela- tions may be described as a characteristic of tions will require exceptions. For example, part of the member. where the underclay of No. 2 Coal is actual- Even though they are in sequence, shales ly a composite of several underclays, it may of radically different character (such as be called the Cheltenham Clay Member. black, gray, and red shales, and some very Thin units representing the feather. eclgc calcareous shales) may be differentiated as NOMENCLATURE OF CYCLO THEMS 2 5 members provided they are well defined, may be given another name. As the word have the general relationship of members, "cyclothem" will always be used when the and have wide distribution. unit is referred to, use of a geographic name The full name of a member, such as already adopted for some other form of Canton Shale Member, should be used at stratigraphic classification does not cause the beginning of a discussion, but there- confusion and is permitted. However, after "Member" may be dropped. names used for other Pennsylvanian strati- graphic units or for other stratigraphic units in Illinois or bordering states should not be applied to a cyclothem in Illinois. Only beds of special significance and of The term cccyclothem"will be capitalized wide distribution should be named. Beds when used with a geographic name, as in may be named even though the member St. David Cyclothem. of which. they are a part is not named. A sequence of three or more of the ten il, bed in one area may be classified as a units of the ideal cyclothem will normally member in another area. However, in the be differentiated as a cyclothem and named. description of a local area, such as a quad- One or two units not in the normal order rangle or county, this practice should gen- of the cyclical sequence but interfingered erally be avoided. within a cyclothem should be treated as Glassification as a member or bed should part of the cyclothem. One or two units be based primarily on relations mentioned may be differentiated as a cyclothem if they above and not on distinctiveness of lithol- occur at a cyclothem boundary, and they ogy or on thickness. For example, less than should be differentiated if a cyclothem is one inch ol No. 5 Coal below black shale recognized at this position elsewhere. and above underclay is recognized as a In an area where the intercalation of member, although a 6-inch coal in the Can- several units within a cyclothem requires ton Shale Member is called a bed. A unit the recognition of two cyclothems, both should be recognized as a member rather should have new names. This will avoict than a bed if the relations permit. the confusion of a cyclothem's having vari- able definitions in different areas. Member names are independent of cyclical classifi- NOMENCLATURE OF CYCLOTHEMS cation and will be unaffected by changes Cyclothems have geographic names. They in cyclothetn names. may be given the same name as a prominent Names such as Upper, Middle, and Lower member or bed in the cyclothem, or they are not acceptable in cyclothem names, McCORMlCK GROUP KEWANEE GROUP McLEANSBORO GROUP 7 I I Caseyville Fm. I Abbott Fm. I Spoon Fm. I Carbondale Fm. I Modesto Fm. I Bond Fm. I Mattoon Frn.

SANDSTONE TI I I I Calcareous sandstones common Clean quartz sandstones Transitional sondstones Argillaceous and micoceous sandstone Quartz pebble conglomerates I I

SHALE -

Includes a widespread variegated clay 25%i( Shales silty and sandy -I siltsfones prorninenl Shales commonly less silty than below; underclays well developed; block fissile shales common

COAL Cools aenerollv thin T Cools thin and discontinuous but traceable Cools generally thin but w~delytroceoble - I I ~ooooa Principal minable coals a

LIMESTONE Limestones generally thin I Limestones rare to absent but traceable Contains two extensively - I OOOOI Limestones relatively uniform and widely troceoble thick and relatively Limestones generally thin but numerous A few thin fossiliferous I pure limestones 1 sondstones

L +- AVERAGE THICKNESS-----*

Scale , '00 f+. Fig. 4. - Distribution of the four principal lithologies in Pennsylvanian strata of Illinois. GENERAL STATEMENT places one in which cyclical sequences, or cyclothems, were treated as formational Strata of Pennsylvanian age in lllinois units, although not formally so designated. are separated from older Paleozoic rocks The reason for applying the name "cyclo- by a major unconformity. In places they them" was to emphasirc the clifferences be- overlap the entire Mississippian, Devonian, tween the cyclical sequences and normal and Silurian Systems and rest on Ordovician formational units. Rejection of the cyclo- rocks as old as the St. Peter Sandstone them as a term 01- a unit of rock-strati- (Weller et al., 1945; Wanless, 1955, p. 1760). graphic classification requires the introduc- Throughout most of the extensive area tion of a nearly complete new sequence of they cover in Illinois, Pennsylvanian rocks formation and group units and names. are overlain by deposits of Pleistocene age. Seven tormations are recognized and Although neither the youngest nor the placed in three groups, as lollows: oldest Pennsylvanian rocks of the Appala- McLeansboro Group chian and Midcontinent regions are recog- Mattoon Formation nized in the Illinois Basin, Pennsylvanian Bond Formation rocks in Illinois include beds equivalent Moclesto Formation to most of the major subclivisions recog- Kewanee Group nized in other areas. Carbondale Formation The Pennsylvanian strata are named for Spoon Formation the state of Pennsylvania (Williams, 1891) , MIcCormick Group and the name has been used in lllinois with Abbott Formation system rank since 1906 (S. Wellel-, 1906, Caseyville Formation fig. 1) . Neither series nor stage subclivisions In general, names ol members are the of the time-stratigraphic classification of same as in the previous clas&cation, ex- Pennsylvanian rocks have as yet been cept for names introduced to replace such adopted by the lllinois Geological Survey, duplications as Curlew Limestone, Curlew but the relation of the sequence to units Coal, and Curlew Sandstone. The geo- recognized in adjacent states is shown on graphic name is retained for only one of plate 1 and relation to units of other such units after a consideration of priority, regions is to be found in the Pennsylvanian extent of use, and relative prominence of correlation chart (Moore et al., 1944) . the unit. X lew names of minor units are In rock-stratigraphic classification, abandoned as unnecessary, particularly ill groups, formations, and members are recog- cases of duplication. Compound names and nized, as previously discussed. The abun- informal nescriptive names for unusual dance of relatively thin but distinctive litho- rock types are changed to the standard for- logic units has made it desirable to recog- mat for formal usage. nize sequences or bundles of these units as TAJhere diif'erent nlember names have formations. The formations differ in the been applied to the same unit in various relative abundance and gross lithologic parts of the state, the name having priority characteristics of sandstones, shales, silt- and widest use is chosen. However, no at- stones, limestones, and coals (fig. 4) . Larger tempt is made to eliminate all such syn- units based on lithologic similarities be- onyms, even where correlations are reason- tween the formational units are recognized ably well established. In some cases the as groups, and the relatively thin lithologic continued use of local names seems prefer- units are recognized as members. able to a choice between long established This rock-stratigraphic classification re- and widely used names. 28 ILLINOIS STATE GEOLOGICAL SURVEY R. 1. 214

The revised classification and a com- of the group, the top of the Murray Bluff posite column of the Pennsylvanian rocks Sandstone, is difficult to recognize in some of lllinois are shown on plate 1. The col- areas because of the variability of the umn is a compilation of representative sec- sequence. tions, mostly those typical of the sequence in Cyclothems in the NlcCormick Group, the type areas of the formations. Because of in contrast to those of the Kewanee Group, considerable variation in thickness and rarely are composed of more than four or lithology throughout the state, the section five different lithologic units. Limestones is generalized and does not include all are generally absent and more than one coal members recognized, particularly in parts usually is present in each cyclothem. of the section where lateral variations are most prominent. A1 though the composite section shows a total of only about 2300 The Caseyville Formation as here defined feet of strata, a composite of maximum includes strata from the base of the Penn- thicknesses of the formations would be more sylvanian to the top of the Pounds Sancl- than 3000 feet. stone. It corresponds to the Caseyville In the following description of the revised Formation as defined by Lee (1916) and classification, all accepted names are listed. probably to strata relerred to as Caseyville Only names that are new, redefined, or Conglomerate by Owen (1856, p. 48) . The otherwise different from those shown on Caseyville as previously used in lllinois the correlation chart compiled by Siever (in (Weller, 1940) is thus redefined to exclude Wanless, 1956) are discussed. Type locali- 40 to 60 feet of strata (including the ties and original references of all named Reynoldsburg Coal) above the Pounds formations and members are listed in Sandstone and below the Grindstaff Sancl- table 1. stone that are now defined as part of the overlying Abbott Formation. McCORMICK GROUP The type area defined by Lee (1916, p. The McCormick Group, which contains 15-16) after Owen (1856) was "measured the Caseyville and Abbott Formations, is from outcrops on the Illinois shore of the the lowest group in the Pennsylvanian of Ohio River between the mouth of the lllinois. The group is here named for the Saline River and Gentry's Landing below village of NlcCormick in northwestern Pope Battery Rock" in Hardin County (geologic County, which is located in an area where section 1, appendix) . A supplementary strata of the two formations are prominent- section for this formation consists of ex- ly exposed. It includes strata formerly in- posures along the Illinois Central Railroad cluded in the Caseyville Group and the cut from the Mississippian-Pennsylvanian lower part of the Tradewater Group. contact about 1% miles north of Robbs to The McCormick Group is characterized the area over the railroad tunnel near Zion by the prominence of thick, commonly mas- Church in Pope County (geologic section sive, relatively pure quartz sandstones that 2) constitute 50 to 60 percent of the strata. The Caseyville is, in general, restricted Sandy shale and siltstone normally make to the southern part of the coal basin in up 40 percent or more of the section. Coals southern Illinois. are characteristically thin and of very limi tecl continuity. Limestones are uncom- LITI-IOLOGY mon to rare, a1 though fossiliferous sandy The Caseyville Formation is characterized beds 01- sandy limestones have been re- by dominance of sands tone and prominent ported locally. development of sandy shale and siltstone Although a number of named members (fig. 4) . Sandstone members are not uncom- in the group have been rather extensively monly of the order of 100 feet thick, and traced in outcrop, they are more difficult to the two sandstone members that have been trace in subsurface. The upper boundary named, Pounds and Battery Rock, form McCORM7CK GROUP 29 prominent bluffs along the Pennsylvanian stratigraphic position of the Sellers Lime- escarpment of southern Illinois. stone is not established, Wanless (1939, p. The Caseyville sandstones are composed 64) indicated its position between the of clean quartz sands and have little clay Gentry Coal (formerly called the Battery or mica. The sandstones contain well Rock Coal) and the Battery Rock Sand- rounded white quartz pebbles, commonly stone. The description of the type section about 1/4 to $4 inch in diameter, although of the Caseyville (geologic section 1) shows pebbles about 1% inches in diameter have limestone between the Pounds Sandstone been reported. In some areas the quartl: and the Gentry Coal. pebbles are distributed throughout the THICKNESS sandstone bodies, but more commonly they The Caseyville Formation is highly vari- are concentrated along bedding planes 01- in conglomeratic lenses. In many exposures able in thickness because the pre-Pennsyl- the quartz pebbles are scarce and are found vanian surface is irregular and because the only by careful search. Secondary enlarge- lormation thins westward toward the west- ment of quartz grains is common and gives ern shelf area and northward from the area sparkle to the rock. The character of these of maximum development in southern Illi- sandstones has been described by Glass et al. nois. Although thicknesses in excess of 500 (1956) , Lamar (1925) , Potter and Olson feet have been reported, a maximum thick- (1954) , Potter and Glass (1958) , Potter and ness of 350 feet is more common.

Siever (1955, 1956a, 1956b) , Rich (1916a, MEMBERS OF THE CASEYVILLE FORMATION 1916b) , Siever (1951) , Siever and Potter (1956), Wanless (1939, 1955), Weller (1940). Southeastern Illinois The character of the sandstones is the most In southeastern lllinois the following useful feature for distinguishing the Casey- members are named: ville from overlying formations. Pounds Sandstone The shaly and silty strata below the prin- Gentry Coal cipal sands tones are characteristically sandy. Sellers Limestone Sandstone benches up to at least 25 feet Battery Rock Sandstone and similar to the principal sandstone mem- Lusk Shale bers occur in the Lusk Shale, the lowest The Gentry Coal Member is named here member. for exposures in Harclin County, near Two or more coal beds have been recog- Gentry Landing (geologic section 1) . Owen nized within each of the more shaly parts (1856) termed this the Battery Rock Coal, of the Caseyville Formation throughout but the name Battery Rock has been more much of the southern Illinois outcrop belt. widely used for the sandstone and is here The coals, however, generally are very thin restricted to the sandstone. and not widely traceable. Only one coal, the Gentry Coal Member, has been widely Southwestern Illinois correlated, but even this is not continuously In southwestern lllinois the following traceable. named members are recognized: Pounds Sandstone In general, limestones have not been ob- Drury Shale served in Caseyville strata, but ~ossiliferous Battery Rock Sandstone sandy beds occur in a few places. Some of Wayside Sandstone the fossils are reworked from Mississippian Like the Lusk Shale Member to the east, and older rocks. The notable exception is the Wayside Sandstone Member is a com- the Sellers Limestone Member, which is ex- plex unit consisting of several beds of mas- posed near Sellers Landing in Hardin sive sandstone separated by silty shale. It County near the Ohio River. It is dark, probably includes strata equivalent to the iron rich, relatively dense marine limes tone Lusk Shale. The sandstones generally are about 2 feet thick. Although the exact lenticular and not widely traceable. Two 3 0 ILLINOIS STATE GEOLOGICAL SURVEY R. 1. 214 or more thin, erratic coals or coaly streaks sequence formerly called the Traclewater axe recogni~edwithin this complex member, Group. one of which was termed Wayside Coal (Kosanke, 1950). The name now is re- LITHOLOGY stricted to the sandstone, and at present Like the Caseyville Formation, the Ab- no name is needed for the coal. bott Formation is characteri~ed by the The name Battery Rock is extended from dominance of sandstone, sancly shale, and southeastern Illinois to southwestern Illi- siltstone. The massive sandstone members nois for the sandstone previously named generally do not attain a maximum thick- Lick Creek. The name Lick Creek is ness as great as do those of the Caseyville. preempted. The sanclstones of this formation may be The Drury Shale Member contains all considered transitional from the relatively strata between the Battery Rock anel pure quart1 sanclstones ol the Caseyville Pouncls Sandstone Members. This unit is Formation to the argillaceous ancl mica- dominantly shale but includes some sancl- ceous sanclstones of higher Pennsylvanian stone and two or more thin, cliscontinuous lormations. The lowermost sandstone is a coals. The name Drury Shale is not used in relatively clean quart/: sandstone, and the southeastern Illinois, where the Gentr? highest sandstone member is more argil- Coal and the Sellers Limestone are rliffer- lxeous and micaceous. entiated in this interval. Sandstones 01 the Caseyville ancl Abbott The Lusk and Drury Shale Members are Formations can best be differentiateel by composite units, but until the) are s~lb- the general absence of quart/_pebbles and divided the names are useful ant1 are re- the greater prominence of clay matrix in tained. the Xbbott sanclstones. A few quart/: peb- The name Pounds Sandstone Member is bles have been reported in sandstone mem- extended to this area to include strata bers of the Xbbott Formation, but they are formerly considered to be the lower part rare. of the Makanda Sandstone, which has been Sandstones and silts tones constitute more subdivided. The name Makancla is clis- lhan 50 percent of the Abbott Formation cont inuecl. (fig. 4) . Although the shales of the Abbott are commonly sandy and silty, like those in The name Abbott Formation is proposecl the underlying Caseyville, there are more here Tor strata from the top of the Pouncls nonsandy, clayey shales than in underlying Sandstone Member to the top of the Bern- strata. atlotte Sandstone Member of western Illi- Coals in the Abbott Formation generally nois. The latter is believed to be equivalent are thicker and much more widely trace- to the Murray Bluff Sandstone Member of able than coals of the Caseyville. However, southern Illinois. The formation is named the coals are rarely more than 24 inches for Abbott Station, which is located about thick and have much less continuity than the mielpoint oE the type exposures of the the higher coals. formation along the Illinois Central Kail- Limestones are generally absent in this road cut in Pope County (geologic section formation but relatively thin, discontin- 3). The Xbbott Formation overlaps the uous, sancly limes tones or fossiliferous Caseyville Formation and throughout most sandstones are associated with at least two of central, northern, and western Illinois of the sandstone members. In Indiana is the basal formation of the Pennsylvanian Ferdinand and Fulda Limestones occur in System. However, it in turn is overlapped strata equivalent to the Abbott Formation. by the younger Spoon Formation on some of the more prominent anticlinal structures. THICKNESS The Abbott Formation consists of strata The Abbott Formation has a nlaximurn that were included in the lower part of the thickness of 300 to 350 Feet in southern KEWANEE GROUP 8 1

Illinois, but it thins westward and north- Member of southern Illinois (Wanless, ward. The Abbott probably is never more 1957) , but pending further studies both than 100 feet thick in western Illinois and names are retained. is generally much thinner. The name Manley Coal Member is pro- posed here for the coal formerly called MEMBERS OF THE ABBOTT FORMATION Babylon Coal. This name is taken from Southern Illinois the small settlement of Manley four miles In the southern part ol Illinois, six mem- west of the type outcrop. The type localit) bers of the Xbbott Formation are recog- remains unchanged (table 1) . niyed: The name Tarter Sandstone, previousl) Murray Bluff Sandstone applied to the sandstone below the Tarter Delwoocl Coal Coal, is cliscontinuect in order to retain the Finnie Sandstone name for the coal. ;Is the sandstone is thin Willis Coal and only locally present, no name is needed. Grintlstaff Sandstone Similarly, the name Pope Creek is re- Reynoldsburg Coal tainecl for the coal and dropped for the The name Boskydell Sandstone usecl on thin, local sandstone, for which a name the chart compiled by Siever (in Wanless, is not deemed necessary. 1956) was applied to the unit called Bosky- dell Marine Zone by Wranless in the same KEWANEE GROUP report, The name has been usecl (Wanless, The Kewanee Group includes the Spoon 1939, 1956; Weller, 1940; t4Jeller et al., and Carbondale Formations. The group 1942; Desborough, 1959) for a bed or an is named for the city of Mewanee in Henry ill-defined zone of fossililerous calcareous County, which lies within the outcrop belt randstone or sandy limestone interbedded ol the formations that constitute this group. with sandstone. Because the name Bosky- This middle group of Pennsylvanian dell has been used for material of this formations is characterized by the wide- lithologic character now believed to occur spread clevelopinent of minable coals. Ap- at more than one horizon, and because the proximately 99.9 percent of the mapped unit generally lacks the distinctiveness and minable coal reserves of Illinois occur in continuity of units recognized as members the Kewanee Group (Cady and others, elsewhere in the Pennsylvanian sequence, 1952) . the name is dropped from formal usage. Sandstones generally compose 25 percent The sandstone formerly called Delwoocl ot the Kewanee Group, compared with 60 is now named Finnie, the name used for- percent ol the underlying McCormick this sandstone in Kentucky (Owen, 1856; Group. The Kewanee sandstones are char- Lee, 19 1 6) . This change was made to rc- acteristically argillaceous and highly rnica- tain the name Delwood for the coal. ceous. Western Illinois The Kewanee Group is marked by the The following members of the Abbot( earliest occurrence of widespread limestones Formation are recognized in western Illi- of relatively uniform thickness. The lime- nois: stones are commonly 1 to 5 feet thick, Bernadotte Sandstone although some locally arc more than 1 0 feet. Pope Creek Coal Cyclic sedimentation is well defined and the cyclothems show perhaps the maximum Tarter Coal variety of rock types. This character is in Manley Coal marked contrast to that of the underlying Babylon Sandstone McCormick Group but is similar to the The Babylon Sandstone is provisionally cyclic character ol at least the lower part correla tet1 with the Grindstaff Sandstone of the overlying McLeansboro Group. 32 ILLINOIS STATE GEOLOGICAL SURVEY R. I. 214

MEMBERS OF THE SPOON FORMATION Spoon Formation is the name proposed Southeastern Illinois here for strata from the top of the Bern- A1 though not all are recognized through- aclotte Sandstone Member to the base of out sou theas tern Illinois, the following the Colchester (No. 2) Coal Member. The members of the Spoon Formation are formation derives its name from exposures named: in a roadcut and railroad cut of the T.P. Balzo Sandstone and W. Railroad about 1/4 mile west of DeKoven Coal Spoon River in Fulton County (geologic Davis Coal section 4) . The Spoon Formation consists Stonefort Limes tone of strata previously included in the upper Wise Ridge Coal part of the sequence formerly called the Mt. Rorah Coal Tradewater Group. Creal Springs Limestone Granger Sandstone LITHOLOGY O'Nan Coal The Spoon Formation contains much less Curlew Limestone sandstone and correspondingly more shale New Burnside Coal Bidwell Coal than the underlying formation (fig. 4) . The sandstones are generally more argillaceous The name Bidwell Coal Member is here- and micaceous than sandstones of the Ab- in proposed for a previously unnamed coal bolt Formation, although this change is a exposed about 3/q mile northeast of the gradational one. They do not differ marked- Bidwell School in Johnson County (geo- ly from sandstones of overlying formations. logic section 5D) . The name New Burnside Coal Member The shales of the Spoon Formation are is applied here to the upper of two coals commonly less sandy than those in underly- mined in the vicinity of the village of New ing strata, and underclays beneath the coals Burnside in Johnson County (geologic sec- and black shales above the coals are gen- tion 5D) . erally better developed. The name O'Nan Coal Member is pro- Coal members, for the most part, are posed here to replace the Curlew Coal in thicker and much more widely traceable order to retain the name Curlew for the than coals encountered in lower formations. limestone. The name is derived from Den- They lack the uniform thickness, and most nis B'Nan Ditch, which flows across the of them lack the very wide continuity, of north tip of Indian Hill (DeKoven 7y2 coals in the overlying Carbondale Forma- minute quadrangle), Union County, Ken- tion. tucky. Although the name is changed, the type area remains the same. A1 though limes tones are relatively minor The name Granger Sandstone Member is in the Spoon Formation, several limestones proposed here to replace Curlew Sandstone of appreciable continuity occur and have in order to retain the name Curlew for the been correlated widely. The limestones limestone. The name is derived from the are not as continuous as those in the overly- village of Grangertown about five miles ing Carbonciale Formation. southeast of Indian Hill in Union County, Kentucky, which is the original type locality THICKNESS of the sandstone. The Spoon Formation has a maximum The name Creal Springs Limestone Mem- thickness of about 350 feet in southern Illi- ber is proposed here for a limestone exposed nois but is thinner in most places. It just above the top of the sandstone quar- ranges from a few feet to nearly 100 feet ried east of Creal Springs in Williamson thick in western Illinois, County (geologic section 5C) . This lime- KEFVAiaTEE GROUP 33

stone previously was correlated with the Western Illinois Curlew Limestone but is now considered The named members of the Spoon Forma- to be younger (Thompson et al., 1959) . tion in western Illinois are as Collows: The name Mt. Rorah Coal Member is Cheltenham Clay proposed here to replace Bald Hill Coal be- Browning Sandstone cause of prior use of the name Bald Hill. Abingdon Coal The type locality of this unit is unchanged (table I), and the name is derived from Isabel Sandstone &It. Rorah Church, about two miles north- Greenbush Coal west of the type outcrop. Wiley Coal The name Wise Ridge Coal Member ii Seahorne Limestone proposed here for the coal formerly called DeLong- Goal Stonefort in order to restrict that name to Brush Coal the Stonefort Limestone. The type locality Hermon Coal is unchanged (table I) and the unit is named for Wise Ridge, about 3 miles west Seville Limestone of the town of Stonefort. Rock Island (No. 1) Coal The type outcrops of the Stonefort Lime- The coals formerly called Lower DeLong, stone Member are in a road cut and in Middle Delong, and Upper DeLong are ravines east of the road in NEX SEl/q sec. lierein named, respectively, the Hermon 25, T. 10 S., R. 4 E., Williamson County. Coal Member, the Brush Coal Member, and This is a correction of the location cited by the DeLong Coal Member. The Hermon Wanless (1956, p. 9) . Coal is named for the village of about 2% miles south of the type exposure; Southwesterm Ililinois the Brush Coal is named for Brush Creek, The following named members of the in the vicinity of the type outcrop; and the Spoon Formation are recognized in south- DeLong Coal is named for the village of western Illinois although not all are recog- DeLong about 1% miles northeast of the nidin the same area: lype outcrop. The type section is the same Cheltenham Clay for all three coals and remains unchanged (table 1) . Davis Goal The Abingdon Coal Member (table I) , Seahorne Limestone not shown on the chart by Siever (in Wan- Vergennes Sandstone le~s,1956) , was named by Culver (1925) . Murphysboro, Litchfield, Northern Illinois and Assumption Coals The names ""Goose Lake" Clay, ""Ottawa" The Litchfield Goal Member and the Clay, and "Utica" Clay are trade names and Assumption Goal Member have been recog- are not recogni~eci as part of the strati- nized only in the vicinity of mines near- graphic nomenclature. The name Chelten- Litchfield in NIontgomery County and 11a1-n Clay Member is extended to this area A4ssumptionin Christian County (table 1) . from western and sou th~vesternIllinois. These coals are tentatively correlated with the Murphysboro (No. 1) and Rock Island Eastern Hllinois (No. 1) Coals, but until their correlation Although a substantial number of widely can be established with greater certainty, traceable members occurs in the Spoon the names are retained for local use. Formation in eastern Illinois, the only The name Cheltenham Clay Member is mcmber that has been named is the Indiana applied locally to a dominantly clay unit IT1 Coal. This coal has been informall) that is a composite of several underclay called the Seeleyville Coal in Indiana, and members. It has a stratigraphic range that the name St.eleyvillc Coal Member is here varies from place to place. accepted for this coal in Illinois (table 1) . 3 4 ILIJNOIS STATE GEOLOGICAL SURVEY R. I. 214

ly highly ciolomitic. Black fissile shales are The Carbondale Formation is here re- particularly well developed over most of the defined to inclucle strata between the base coals, and underclays are uniformly present. of the Colchester (No. 2) Coal and the top Cyclic sequences have a wider variety of of the Danville (No. 7) Coal. The Carbon- lithologic units than occur in lower forma- dale Formation was originally named by tions. Shaw and Savage (1912) for the town of THICKNESS Carbondale, which is in the outcrop belt The Carbondale Formation is commonly of strata of this formation. As originally 225 to 300 feet thick, but in parts of north- defined, the CarbontIale included strata ern, western, and southwestern Illinois from the bottom of the Murphysboro Coal the formation thins to about 125 feet, local- to the top of the Herrin (No. 6) Coal. The ly even less. In part of southeastern Illinois, Murphysboro Coal was then considered the formation is nearly 400 feet thick. equivalent to the No. 2 Coal ol western Illinois. The intent was to use the No. 2 MEMBERS OF THE CARBONDALE FORMATION Coal as the base of the Carbondale and, Southern Illinois except at M~rphy~boro,it was so used. Later the Carbondale was redefined as a The named members in the Carbondale group (Weller, 1940, p. 36) and the bound- Formation in southern Illinois are as fol- aries moved to include strata from the base lows: of the Palm Sandstone to the base of the Danville (No. 7) Coal Anvil Rock Sandstone (MTillman and Galurn Limes tone Payne, 1942, p. 87, 95) . The present re- Allenby Coal definition shifts the boundaries again, but Bankston Fork Limestone the major part of the unit remains the same. Anvil Rock Sandstone No type locality other than the vicinity Conant Limestone of Carbondale was proposed To define Jarnestown Coal the formation in an area where No. 2 Coal Brere ton Limes tone is well clevelopeti ;mil the formation more Herrin (No. 6) Coal completely exposed, a type section is here Vermilionville Sandstone designated for this unit in Fulton County, Briar Hill (No. 5A) Coal Illinois (geologic scction 6) . St. David Limestone Harrisburg (No. 5) Coal LITHOLOGY Manover Limes tone The (hrbontiale Forrna tion is dominant- Summum (No. 4) Goal ly gray shale (fig. 4) , but sandstones are Roodhouse Coal prominent locally and have a maximum Shawneetown Coal thickness oC abou t 100 Tce t. The sand bodies are generally linear in their maximum de- Colchester (No. 2) Coal velopment and are interpreted as filled The name Colchester (No. 2) Coal Mem- channels. The formation is characterized ber is now extended to the No. 2 Coal by wide distribution of coals and lime- I hroughou t Illinois. stones. Many of the coals are relatively The name Shawneetown Coal Member thick, commonly ranging from 2 to 7 feet is herein proposed For the coal believed to and in some areas up to 15 kt. The forma- be the lower of two coals formerly called tion includes the principal coals that No. 2A (Harrison, 1951) . Some reports have been most extensively mined in Illi- have referred to the two coals noted be- nois. Several limestone members are near-1) tween No. 2 Coal and No. 4 Coal as the No. as extensive as some of the coals. The lime- 2A Coal, but this name is now discarded. stones are usually about 1 to 5 l'eet thick, The Shawneetown Coal has not been recog- but some are locally thickor. They usually nized in outcrops in Illinois but was en- are relatively argillaceour. X few are local- countered at a depth of 543 feet 10 inches KEVVANEE GROUP 35 in Union Colliery Company drill hole 28, Copperas Creek Sandstone located in sec. 23, T. 9 S., K. 9 E., Gallatin Pokeberry Limestone County, Illinois. A coal horizon at a depth Lawson Shale of 504 feet 11 inches in this drill hole may Brereton Limestone be the position of the upper coal but is not Herrin (No. 6) Coal formally named. Representative samples Big Creek Shale of this diamond drill core, including the Vermilionville Sandstone Shawneetown Coal, are in the core file of Canton Shale the Illinois Geological Survey (core 2639) . St. David Limestone The Roodhouse Coal Member is recog- Springfield (No. 5) Coal nized only in the vicinity of Roodhouse in Cove1 Conglomerate Greene County. Hanover Limes tone The narne Summum (No. 4) Coal Mem- Summum (No. 4) Coal ber is here extended to No. 4 Coal through- Kerton Creek Coal out Illinois. Pleasantview Sandstone The name Vermilionville Sandstone Purington Shale Member is extended from northern Illinois Oak Grove Limestone to the equivalent sandstone in southern Lowell Coal Illinois for which the name Cuba Sandstone *JakeCreek Sandstone has been used. The name Cuba was pre- Francis Creek Shale empted. Colchester (No. 2) Coal The name Brereton Limestone Member is extended to the caprock limestone of No. The name Colchester (No. 2) Coal Mem- 6 Coal in southern Illinois to replace the ber is extended from western to northern name Herrin, now restricted to the Herrin Illinois to replace the name LaSalle (No. 2) (No. 6) Coal Member. Coal so that the name LaSalle can be re- tained for the LaSalle Limestone. Conant Limestone Member is the name here proposed for the limestone lorrnerly The name Oak Grove Limestone Mem- called Jamestown. The name Jamestown ber replaces the name Oak Grove Beds. will be used lor the coal beneath the lime- Although it is a complex unit consisting of stone. The narne is derived from the vil- interbedded limestone and shale, it is lage of Conant in Perry County, Illinois, designated as a limestone because its most about 2 miles east of the type outcrop distinctive elements are limes tone and it which is unchanged (table 1) . occurs at a position in the cyclical sequence nornlal for a limestone. The name Allenby Coal Member is pro- posed here lor the coal formerly called The name Vermilionville Sandstone Bankston, so that the name may be re- Member is extended from northern to west- stricted to the Bankston Fork Limestone. ern Illinois to replace the name Cuba Sand- The new name is derivecl from the village stone. The name Cuba was preemptecl. of Allenby in Saline County, about half a The name Lawson Shale Member is pro- mile southwest of the type outcrop, which posed here for the shale above the Brere- is not changed (table 1). ton Limestone Member in western Illinois, The name Danville (No. 7) Coal Menl- formerly called SheKielcl Shale. The name ber is extended to No. 7 Coal throughout Sheffield was preempted. The name Law- Illinois. In southern Illinois it replaces the son is derived From Lawson Creek, about name Cutler (No. 7) Coal. a mile west of the type exposure, which has not been clzanged (table 1) . Western and Northern Illinois The name Danville (No. 7) Coal Mem- The following members of the Carbon- ber is extended from eastern Illinois to the dale Formation are recognized in western equivalent unit in northern and western and nor tliern Illinois: Illinois, replacing the name Sparland (No. Danville (No. 7) Coal 7) Coal. 36 ILLINOIS STATE GEOLOGICAL SURVEY R. 1. 214

Eastern Illinois The McLeansboro Group has a maxi- The following named members of the mum thickness of about 1200 feet in Jasper Carbondale Formation are recognized in County, but more than 1600 feet of Mc- eastern Illinois: Leansboro strata recently have been re- Danville (No. 7) Coal ported from a test hole in western Kentucky Herrin (No. 6) Coal within a few miles of Illinois. Harrisburg (No. 5) Coal Summum (No. 4) Coal Shawneetown Coal The Modesto Formation includes all Colchester (No. 2) Coal strata from the top of the Danville (No. 7) Coal Member to the base of the Shoal Creek The name Colchester (No. 2) Coal is Limestone Member. It is named here for extended to the No. 2 Coal throughout the town of Modesto in northern Macoupi~i Illinois. County where there are prominent outcrops The name Shawneetown Coal is extended of the formation. The formation is nearly to this area from southeastern Illinois. It completely exposed in Macoupin County is applied to the lower of two coals com- in four sections described previously by monly encountered between No. 2 Coal Payne (1942) and Ball (1952) (geologic and No. 4 Coal near the Illinois-Indiana section 7) that are here designated type ex- boundary in eastern Illinois. Siever (in posures. Wanless, 1956) referred to both coals as No. 2a Coal. LITHOLOGY The name Herrin (No. 6) Coal is ex- The Modesto Formation is dominated by tended to eastern Illinois and replaces the gray shales (fig. 4), but sandstones are lo- name Grape Creek Coal. cally prominent. The formation differs l'rom the Carbonclale Formation below in having thinner coals, thicker limestones, McLEANSBORO GROUP ancl by a greater abundance of red shales. The McLeansboro Group inclucles the It differs from the Bond Formation above Modesto, Bond, and Mattoon Formations. in having thinner limestones and more McLeansboro Formation was the name prominent sandstone members. Coals of the originally applied to all Pennsylvanian iVIoc1esto are rarely more than a loot thick, strata above the No. 6 Coal as described but most ol' them are widely distributed. Srom cores oS two diamond drill holes near Sandstones locally may be as much as 75 AfcLeansboro in Hamilton County (De- I'eet thick in filled channels. Most of the WolS, 1910) . The McLeansboro later was limestones are thin and very argillaceous, elevated to a group (Weller, 1940, p. 36) , and the base of the Copperas Creek (Anvil with the exception of the Piasa and Lons- Rock) Sandstone (Willman ancl Payne, dale Limestones of western and southwest- 1942, p. 87, 135) was made the base of the ern Illinois and the West Franklin Lime- group. As herein redefined the McLeans- stone in southeastern Illinois. Cyclic se- boro Group includes all strata above the quences are well developed, and some top of the Danville (No. 7) Coal. cyclothems contain nearly the maximum The McLeansboro Group differs from number of lithologic types. the Kewanee Group below in that its lime- stones are more abundant and thicker and THICKNESS its coals thinner (fig. 4). Most of the The Modesto Formation is commonly cyclothems show a proportionately greater about 300 feet thick, but it has a maximum development of the marine units than do thickness of more than 400 feet in south- the lower cyclothems. The coals commonly eastern Illinois. The formation is only are less than one foot thick, but locally are about 200 feet thick in its local occurrences ns much as 36 inches thick. in northern Illinois. McLEANSBORO GROUP 37

MEMBERS OF THE MODESTO FORMATION called informally the "3rd Cutler Rider Southeastern Illinois Coal" (Kosanke, 1950; Wanless, 1956) . The following named members are recog- Although the Pond Creek and Lake ni~edin the Modesto Formation of south- Creek Coal Members may have surface ex- eastern Illinois: posure, no outcrops have been recognized New Haven Coal with certainty. These and the DeGraff Chapel (No. 8) Coal Coal have been encountered in several drill Trivoli Sands tone holes in the general area. The Survey has West Franklin Limestone on file cores of all three coals from a drill Lake Creek Coal hole in NEX STV1/4 SEX sec. 18, T. 7 S., Pond Creek Coal R. 4 E., Franklin County (core 3732) . DeGraff Coal The name Chapel (No. 8) Coal Mem- Piasa Limestone ber is extended lrom the type area in The name Piasa Limestone Member is western Illinois to the coal formerly called ex tended to southeastern and southern Illi- No. 8 Coal in southern Illinois. nois from the type area in Jersey County Southwestern Illinois (table 1) . The name replaces that of Cutler The largest number of named members Limestone, which has been tliscontinuetl of the Modesto Formation is in south- because the name is preempted. western Illinois where the following mem- The Piasa Limestone and DeGraff, Pond bers have been named: Creek, and Lake Creek Coals may be in- New Maven Coal cluciect in the complex West Franklin Lime- Macoupin Limes tone stone Member in the eastern part of the area. T/\Tomac Coal Uurroughs Limestone The name DeGraff Coal Member (Cacly, Carlinville Limestone 1950, unpublished manuscript) is accepted Chapel (No. 8) Coal here for a coal exposed along Galum Creek in the SE coi-, NE% sec. 21, T. 5 S., K. 4 Mr., Trivoli Sandstone Perry County, Illinois. The name is derived Sco ttville Limes tone I'rom the DeGraff School about one mile Athensville Coal northeast of the exposure. This coal has Kock Branch Coal been called informally the "1 st Cutler Piasa Limestone Rider Coal" (Kosanke, 1950; Tyanless, The name Kock Branch Coal Member 1956) . is here applied to the coal previously called Pond Creek Coal Member is the name Scottville so that the latter name can be proposed here for a coal reported at a depth restricted to the Scottville Limestone. The of 125 feet in Consolidated Coal Company coal is named for Rock Branch, in north- drill hole 91 in SWX NEX NE% sec. 21, west Macoupin County, along which it is T. 8 S., R. 3 E., Williainson County. Thc exposed. The type locality is unchanged coal is named for the creek that flows (table 1) . through the northern part of the township. The name Athensville Coal Member is This coal has been called informally the here introduced for the coal formerly called "2nd Cutler Rider Coal" (Kosanke, 1950; kipper Scottsville. The name is from the Wanless, 2956) . \rillage of Athensville in Greene County The name Lake Creek Coal Member about 4% rnile~to the southwest of the (Cady, 1950, unpublished manuscript) is type locality, which is the same as that oT accepted here for a coal encountered at a the Rock Branch Coal. depth of 86 feet 7 inches in the drill hole The name Clzapel (No. 8) Coal, ex- clescribecl above. The name is derived tended lrom the type area in western Illi- trom Lake Creek Township in which the nois, replaces the name Trivoli (No. 8) tlrill hole is located. This coal has been Coal formerly used in this area. 38 ILLINOIS STATE GEOLOGICAL SURVEY R. 1. 214

The name Burroughs Limestone Mem- Eastern Illinois ber is here restricted to the middle sandy Only the Chapel (No. 8) Coal and West limestone unit of the strata formerly called Franklin Limestone Members are named in Burroughs Beds (Ball, 1952, p. 38) . The the Modesto Formation in eastern Illinois. type outcrop remains unchanged (table 1). The name Chapel (No. 8) Coal is extended The name Mromac Coal Member is pro- to the eastern part of the state from the posed here for the coal formerly called type area in western Illinois. Macoupin Coal. The coal is named for the village of Womac, Macoupin County, approximately three miles northeast of the The name Bond Formation is here pro- type exposure, which is unchanged. The posed Sor strata extending from the base name Macoupin is restricted to the Macou- of the Shoal Creek Limestone Member to pin Limestone. the top of the Rfillersville Limestone Mem- The name New Haven Coal Member is ber. This Sormation is named for Bond exteideci from southeastern lllinois to the County where exposures of the formation equivalent coal below the Shoal Creek are proininent. The type section is a com- Limestone Member. posite of seven exposures (geologic sec- tion 8). Western and Northern Illinois A relerence section lor the: Bond Forma- The named members ol the Modesto tion is a core from a cliainond drill hole in Formation in western and northern lllinois sou theas tern Chris tian County (geologic are as follows: rection 9). Twenty-eight representative Cramer Limestone samples oS the lorination from this core are Chapel (No. 8) Coal in the core file oS the Illinois Geological Trivoli Sandstone Survey (core C-2NN). Exline Limes tone Lonsdale Limes tone LITHOLOGY Gimlet Sandstone The Bond Formation is characteri~edin Farmington Shale the area of its typical development by thick limestones, in particular its bounding units The name Chapel (No. 8) Coal Meni- (fig. 4). Tlii-ougliout much of the area ber replaces the name Trivoli (No. 8) Coal ol its occurrence, the Shoal Creek Lime- so that the name Trivoli can be retained stone commonly ranges from 5 to 15 feet For the Trivoli Sandstone. The name is thick. The Millersville Limestone Member derived from Graham Chapel, about two attains a maximum thickness of nearly 50 miles north of the type locality, which is Seet in Christian County, although thick- unchanged (table 1) . nesses oS 20 to 30 feet are more common. The name Cramer Limestone Member is The strata between these limestones are proposed for the unit formerly called Tri- predominantly shale, although sandstones voli Limestone and is namecl for the village are prominently clevelopeci in some areas. of Cramer, Peoria County, about 1 1 13 miles In southeastern Illinois, the upper part of southwest of the type locality, which re- the Sormation is dominantly shale and the mains unchanged (table 1) . position of the hlillersville Limestone is The name Turner Limestone, inlormally determined with some clifficulty. Coal used in northern Illinois, is discontinued. members are generally less than a foot The limestone is believed to be equivalent thick, but several appear to be widely to the Cramer Limestone. traceable. Limes tones be tween the bound- The name Hicks Limestone is cliscon- ing members are usually xTery argillaceous tinued because it is preempted. It is not and si~nilar in lithology to comparable considered desirable to propose a new name linlestones in the unclerlying Modesto Sor this unit at this time. Formation. In northern Illinois the forma- McLEANSBORO GROUP 39

tion is comparatively thin, lacks sandstones, ing the'I\Titt Coal. The name is taken from and has a relatively high proportion of the village of Coffeen, which is located limes tones and calcareous shales. Cyclic about 5 miles southwest of the type ex- sequences are well developed in this,fornla- posure. The type locality is the same as tion. that for the Witt Coal (geologic section 8C). THICKNESS In the type area, the Bond Formation is Southeastern and Eastern Illinois nearly 300 feet thick, and it probably The following named members of the is thicker in southeastern Illinois. East of Bond Formation in southeastern and east- the LaSalle Anticline in east-central Illinois ern Illinois are not all recognized in the and also in northern Illinois the formation same area: is 75 Seet or less thick. Livingston and All illersville Limes tones A4EMBKR.S OF THE BOND FORMATION Reel Limes tone Flannigan Coal Central and Southwestern Illinois M t. Carmel Sands tone Eight members have been named in the Shoal Creek Limestone Rond Formation of the central and south- western part oS Jllinois: A11 named members retain yreariousl y Millersville Limestone established usage (table 1 ). The Living- Coff'een Limes tone 5 ton Limes tone Member is recognized east Wit t Coal of the LaSalle Anticline and the equivalent Flat Creek Coal iCIillersville Limestone Member (geologic Bunje Limestone section 8R) is recognifed west of the anti- Soren to Limestone cline. McWain Sandstone The Livingston Limestone Member in Shoal Creek Limestone some areas has ttvo benches that have been The name Sorento Limestone Member referred to as Upper and Lower Livingston (Simon, 1946, unpublished manuscript) is (Siever, in Wanless, 1956). The terms at cepted here for a limestone exposecl just "upper" and "lowcr" will be used only in west of the village oS Sol-ento in Bond the informal sense and not capitalized. County (geologic section 8F). The name Bunje Limestone Member Northern Illinois (Simon, 1946, unpublished manuscript) is In northern Illinois, only the Hall Lime- accepted here ior a limestone exposed stone Member and the LaSalle Limestone about one mile due south 01 the village Member are formally rnmetl. of Bunje in Rond Gountj (geologic sec- tion 8E). MATTOONFOR;\/IATIOK The name Flat Creek Coal Member The Mattoon Formation is proposed for (Simon, 1946, unpublished manuscript) is all Pennsylvanian strata above the top of accepted here for an outcrop of the coal the Millersville Limestone Member. The along Flat Creek in northwestern Bond formation is named for the city of Mattoon, County (geologic section 8D). which lies in the general outcrop belt of The name Witt Coal Member (Glusko- the unit. ter, 1958, unpublished manuscript) is ac- Compared to those of lower formations, cepted here for a coal exposed about 6v2 outcrops of the Mattoon are relatively dis- miles due south of the town of Witt in continuous and widely scattered. In the southeastern Montgomery County (geologic area underlain by Mattoon strata the prin- section 8C). cipal minable coals lie at their greatest The name Coffeen Limestone Member depths, and consequently there has been (Gluskoter, 1958, unpublished manuscript) little diamond drill exploration. Electric ir accepted here for the limestone overly- log data also are lacking because logging of 40 ILLINOIS STATE GE;:03dOGICAlJSURI'EY R. I. 214 oil test holes generally starts below 100 feet following members have been named: and many logs do not record the upper Reisner Limestone 150 to 300 feet of strata. As a result less Woodbury Limestone information is available about the Mattoon Gila Limes tone Formation than about the underlying Greenup Limes tone formations. Rogo ta Limes tone It is therefore not possible to compile a Efingham Limes tone complete sequence for a type section. The Shumway Limes tone best reference section that can be given Omega Limes tone at present consists of an oil test hole

The name Bonpas Limestone Member is preempted. The limestone is named (geologic section 101) is here proposed to for Reisner School 1% miles southwest of replace the name Calhoun Limestone in the type outcrop (geologic section 10A). order to restrict the name Calhoun to the The Newton Cyclothem name is un- underlying coal. The limestone is named changed. Type outcrops (table 1) have For Bonpas Creek, about 1% miles to the been designated within type areas de- east of the type outcrop (table 1). scribed by Newton and Weller for each The name Effingham Limestone Nfem- cyclothem. ber (geologic section 1OF) is here pro- posed for the marine limestone exposed in Eastern Illinois a tributary to Salt Creek half a mile south In eastern Illinois the only named mem- of Effingham (table 1). The informal bers of the Mattoon Formation are the name "Effingham" Beds used earlier (Wan- Cohn Coal Member and the Merorn Sand- less, 19.56) is discontinued. stone Member. The Cohn Coal Member The names Bogota Limestone Member (geologic section 10K) is here named for (geologic section 1OE), Greenup Limestone an outcrop described by Newton and Member (geologic section 1 OD), Gila Weller (1937) two miles southeast ol Limestone Member (geologic section 1OC), Cohn, now called Livingston, in Clark and Woodbury Limestone Member (ge- County (table 1 ). ologic section f OR) are here formally 1)ro- posed for limestone units (generally ma- Northern Illinois rine) in their respective cyclothems, de- Only the lowermost strata of the Mat- scribed by Newton and Weller (1937). toon Formation are exposed in northern The name Reisner Limestone Member is Illinois. The Little Vermilion Limestone proposed here to replace the name New- Member is the only named unit of the ton Limestone because the name Newton Mattoon Formation in this area. CYCLICAL CLASS

GENERAL STATEMENT nois previously referred to the Liverpool Cyclothem (Willman and Bayne, 1942, The cyclical classification is retained p. 95-102). The Liverpool Cyclothem in but is entirely independent of rock-strati- that region consisted of only the lower graphic classification, as previously noted. members of the type Liverpool. The Oak It is, however, modified to conform to Grove Limestone and the Purington Shale standard stratigraphic practice. X few Members, which are the upper part of the new cyclothem names are introduced, du- Liverpool Cyclothem in the type area in plicate names are replaced, and the pre- western Illinois, were included in the viously accepted order changed in a few Lowell Cyclothem, because of the inter- places. No attempt is made to complete fingering of a coal, underclay, and sand- the sequence of cyclothems in parts of the stone in the base ol the Oak Grove Lime- section or in areas where cyclothems have stone. Adoption of the name Tonica not been formally differentiated. Some Cyclothem for the lower Liverpool strata complex sequences are treated as incli- wherever the Lowell Cyclothem is well vidual cyclo therns. enough developed to be named should Accepted cyclothem names are shown lessen the confusion. on plate 1 and in tables 2 and 3. The references listed include the principal re- The name Tonica is derived from the ports that describe the cyclic sequences, Lown ol: Tonica, LaSalle County, 3 miles variously called "formations," "cycles," or southeast of the type section. The type "cyclothems" in the publications. locality is the same as that of the Lowell Cyclothem and occurs along the Vermilion NAME CHANGES River half a mile west of Lowell in La- Salle County (Willman and Payne, 1942, geol. Fec. 33, p. 299-300). The name Hermon C;)iclotllenl is herein The location of the type outcrops of the applied to the cyclothein formerly called S ummum Cyclo them was incorrectly given Lower DeLong (Wanless, I 93 la). The in the 1956 report by Wanless (p. 10). village of Hermon is about 2% miles The type exposure is in T. 3 N., at the south of the type locality, which is un- same site as the type outcrop of the Sum- changed. The type locality is the same 21s mum (No. 1) Coal hlember (table 1 ). that for the Hermon Coal (table 1). The name Brush Cyclothem is herein applied to the cyclothem formerly called The location of the type locality of the the Middle DeLong (Wanless, 1931a). It S tonefor t Cyclothem reported by Wanless is named for Brush Creek in the vicinity (1956, 11. 9) was incorrect. The correct of the type locality of the cyclothem, location Is NEg SE1h sec. 25, T. 10 S., which is the same as the type locality oi R. 4 E.. Williamson County. the Brush Coal (table 1). The name Liverpool Cyclothem, ex- The name DeLong Cyclothem is herein tended in southern Illinois by Siever (in ayplied to the cyclo them formerly called Wanless, 1956) is discontinued for that the Upper DeLong (Wanless, 1931a). The area because it included strata not in type outcrop is unchanged and is the same the Liverpool Cyclothem in the type area. as that for the type locality of the DeLong Until further detailed work is done to Coal (table 1). delineate cyclothemic units in southern The name Tonica Cyclothem is pro- Illinois, no replacement name will be posed here for the ytrata in northern Illi- proposed. CYCLICAL CLASSlPICATION 4 3

The name Crab Orchard Cyclothem, in- The Sorento, Bunje, and Flat Creek dicated by Siever (in Wanless, 1956), is Cyclothems, originally described by Simon dropped because of prior use of the name. (1946, unpublished manuscript) and in- Briar Hill Cyclothem is proposed for this formally introduced by Wanless (1955, unit, which contains the Briar Hill (No. 1956), are herein formally recognized. 5A) Coal Member. The name is derived The Sorento Cyclothem is named for the from Briar Hill near the village of De- village of Sorento, Bond County, which Koven, Union County, Kentucky. lies just east of the type outcrop (geologic The name Cutler Cyclothem was intro- section 8F). The Bunje Cyclothem is duced by Siever (in Wanless, 1956) in named for the village of Bunje, Bond southern Illinois. Strata of this cycle have County, one mile north of the type out- been referred to the Sparland Cyclothem, crop (geologic section BE). Flat Creek but strata included in the cycle in south- Cyclothem is named for Flat Creek, south- ern and southwestern Illinois do not in- western Bond County, where strata of the clude all of the strata included in the cyclothem are exposed. The type outcrop Sparland Cyclothem. The type locality in is described in geologic section 8D. sections 2 and 3, T. 6 S., R. 4 W., Perry The Wit t G yclo them, originally named County, was formerly the type outcrop of and described by Gluskoter (1958, unpub- the Cutler Limestone, a name now dis- lished manuscript) is formally proposed. continued because of extension of the It is named for the village of Witt, Mont- name Piasa Limestone Member to this gomery County, about 6 miles north of the area. type outcrop (geologic section 8C) . Group, formation, and member/ County ; Quadrangle ' T. R. Sec. ; Part 1 Original references to (aj name (b) type locality 1 I I McCormicB Group Pope Harrisburg- Vicinity of McCormick, NW part of county a, b) Present report Brownfield Casey ville Formation Hardin Shawneetown 11S IOE &Alongthe Ohio River a) Owen, 1856, p. 48 between Saline River and b) Lee, 1916, p. 15-16 Gentry Landing Lusk Shale Member Pope Harrisburg- 12-13s 6E .%long Lusk Creek a, b) Weller, 1940, p. 36 Brownfield Wayside Sandstone Nlem- j ackson Carbondale 11s 2E 30 Nx a) Lamar, 1925, p. 84-85 ber b) Wanless, 1956, p. 9 Battery Rock Sandstone Hardin Shawneetown 11s 10E 26 Along the Ohio River a, b) Cox, 1875, p. 204 Member bluff Drury Shale Member Jackson Carbondale 10s 1W 33, 34 Along Drury Creek a, b) Lamar, 1925, p. 91-95 Sellers Limestone Member Hardin S hawneetown 11s lOE 21 SE a) Wanless, 1939, p. 36, 101 b) Wanless, 1956, p. 9 Gentry Coal Member Hardin Shawneetown 11s 10E 26 SW a) Present report. Previous name, Battery Rock Coal (Owen, 1856, No. 1 vertical section; Worthen and Engelmann, 1866, p. 360-361) b) Present report Pounds Sandstone Melnber Gallatin Equality 10s 8E 35, 36 Along Pounds Hollow a, b) Weller, 1940, p. 38

Abbott Formation Pope Harrisburg 1 LS 5E 5-7, NW (5) to SE SW (19) a, b) Present report 18-19 Reynoldsburg Coal ohnson Marion 11s 4E 32 Wsnorth of Cedar a, b) Weller, 1940, p. 39 Member Creek Grindstaff Sandstone Gallatin Equality 10s 8E 28 NE corner a, b) Butts, 1925, p. 44 Member Babylon Sandstone Fulton Avon 7N 1E 14 NENE,Wbankof a) Wanless, 1931~1,p. 189-190, 192-193 Member Spoon River b) Wanless, 1956, p. 9; 1957, p. 65 and geol. sec. 41. D. 205 Manley Coal Member Fulton Avon 7h' 1E 14 NE NE, W bank of a) ~re'sent report. Previous name, Babylon Spoon River Coal (Wanless, 1931a, p. 189-190, 192-193) b) Wanless, 1957, p. 66, geol. sec. 41, p. 205 Willis Coal Member Gallatin Equality 10s 9E 30 SE SW a, b) Butts, 1925, p. 62-63 and pl. I11 Tarter Coal Member Fulton Vermont 5hT 1E 2 SE a) Wanless, 1939, p. 15, 103 b) Wanless, 1956, p. 9; 1957, p. 67, geol. sec. 34, p. 202 Finnie Sandstone Member Union, Ky Shawneetown Along road for less than 2 miles N of Mulfordtown a) Owen, 1856, No. 1 vertical section b) Glenn, 1912b, p. 14 Delwood Coal Member Pope Harrisburg 11s 6E 3 NWNW a) Weller, 1940, p. 40 b) Wanless, 1956, p. 9; Wanless field note Pope Creek Coal Member tMercer -4lexis 14N 2W 33 Center a) Wanless, 1931a, p. 189-190, 192 b) Wanless, 1929, p. 52, geol. sec. 4, "Suite 1"; Wanless, 1956, p. 9 Murray Bluff Sandstone Saline Harrisburg a, b) Weller, 1940, p. 40 Member Hernadotte Sandstone Fulton Vermont a) Savage, 1927, p. 307-316 Member b) Wanless, 1956, p. 9; 1957, p. 70-72, geol. sec. 37, p. 103 Kewanee Group Henry Vicinity of Kewanee a, b) Present report Spoon Formation Fulton Vermont 6N 1E 22 NE SE a, b) Present report Bidwell Coal Member Johnson Marion 11s 4E 5 NESESW a, b) Present report Rock Island (No. 1) Rock Island Vermont 6N 1E 23 SW SW, SW bank a) Worthen, 1868, p. 6; Bement, 1910, p. 197, Coal Member Spoon River table 9 b) Wanless, 1957, p. 72 and geol. sec. 33, p. 201 Murphysboro Coal Jackson Murphysboro- a) Worthen, 1868, p. 11-12 Member -41to Pass b) Wanless, 1956, p. 9 Litchfield Coal Member Montgomery Mt. Olive 9N 5W 32 SE NE YE; mine a, b) Kay, 1915, table 9 and footnote, p. 139 Assumption Coal Member Christian Assumption 12N 1E 2 NE NW SE; mine a, b) Cady, 1935, p. 53 New Burnside Coal Johnson Marion 11s 4E 5 SESESM7 a) Weller, 1940, p. 42 Member b) Present report Seville Linlestone Member Fulton Vermont a) Wanless, 1931a, p. 189-192 b) Wanless, 1956, p. 9; 1957, p. 72-73 and geol. sec. 33, p. 201 Curlew Limestone Union, Ky. Shawneetown South side of Indian Hill, near Curlew a) Owen, 1856, vertical diagram 1 Member b) Glenn, 1912b, p. 24 O'Nan Coal Member Union, Ky. Shawneetown Indian Hill, near Curlew a) Present report. Previous name, Curlew Coal (Owen, 1856, p. 47) b) Glenn, 1912b, p. 25 Hermon Coal Member Knox Galesburg 9N 2E 6, 8 Along Brush Creek a) Present report. Previous name, Lower De- Long Coal (Wanless, 1931a, p. 188-192) b) Wanless, 1956, p. 9; 1957, p. 73-74 Granger Sandstone Union, Ky. Shawneetown Indian Hill, near Curlew a) Present report. Previous name, Curlew Sand- Member stone (Owen, 1856, vertical diagram 1) b) Glenn, 1912b, p. 24-26 Brush Coal Member Knox Galesburg 9N 2E 6, 8 Along Brush Creek a) Present report. Previous name, Middle De- Long Coal (Wanless, 1931a, p. 188-192) b) Wanless, 1956, p. 9; 1957, p. 74-75 Creal Springs Limestone Williamson Marion a, b) Present report Member Mt. Rorah Coal Member Williamson Harrisburg a) Present report. Previous name, Bald Hill Coal (Cady, 1926, p. 260) b) Cady, 1926, p. 260 DeLong Coal Member Knox Galesburg 9N 2E 6, 8 Along Brush Creek a) Present report. Previous name, Upper De- Long Coal (Wanless, 1931a, p. 188-192) b) Wanless, 1956, p. 9; 1957, p. 73-76 - -- I Group, formation, and member County I Quadrangle 1 7'. / R. / Sec. Part / Original references to (a) name (b) type locality

Wise Ridge Coal Member Williamson Harrisburg a) Present report. Previous name, Stonefort Coal (Wanless, 1939, p. 30, 103) b) Present report Stonefort Limestone Williamson Harrisburg a) Henbest, 1928, p. 70-71 Member b) Present report Vergennes Sandstone Jackson Murphysboro a, b) Shaw and Savage, 1912, p. 7 Member Seahorne Limestone Fulton Havana a) Wanless, 1931a, p. 191 Member b) Wanless, 1956, p. 9; 1957, p. 76 and geol. sec. 30, p. 200 Wiley Coal Member a) Wanless, 1931a, p. 191 b) Wanless, 1956, p. 9; 1957, p. 79 and geol. sec. 42. p. 206 Davis Coal Member Union, Ky. Shawneetown Davis Mine, f/z mile E of DeKoven a) old- ref. to Owen, 1856, incorrect; present usage from Lee, 1916, p. 19, 30 b) Wanless, 1956, p. 10 Greenbush Coal Member Warren &lvon a) Wanless, 1931a, p. 191 b) Wanless, 1956, p. 10; 1957, p. 81 and geol. sec. 40, p. 205 DeKoven Coal Member Union, Ky. Shawneetown Near DeKoven Station a, b) Lee, 1916, p. 30 Isabel Sandstone Member Fulton Havana 4N 3E 16 WVNE a) Wanless, 1931a, p. 192 b) Wanless, 1956, p. 10; 1957, p. 83 and geol. sec. 28, p. 199 Palzo Sands tone Member Williamson Marion a) Cady, 1942, p. 9; Weller et a]., 1942, p. 10, footnote b) Wanless, 1956, p. 10 Cheltenham Clay Member St. Louis, Mo. Cheltenharn dibtrict, St. Louis a, b) White, 1909, p. 293 Abingdon Coal Member Knox Gales burg 9N 2E h Center a) Culver, 1925, p. 75 b) Weller et al., 1942, p. 1589 Seeleyville Coal Member Vigo, Ind. 12N 7-8W Mines in vicinity of a, b) Present report. Previous name Coal Ill Seeleyville, hd. (Ashley, 1838, p. 105-107) Browning Sandstone Schuyler Beardstown 2N 1E 18 a) Searight ms., 1929; Wanless, 1939, p. 14, 78 Member b) Wanless, 1956, p. 10; 1957, p. 86

Carbondale Formation Jackson Vicinity of Carbondale, 1llinois a) Shaw and Savage, 1912, p. 6 Fulton Glashrd 7N 4E 1 SENE b) Present report Canton 8N 3E 20 NW NE NCV Canton 8N 3E 21 Sm7 cor. Colchester (No. 2) McDonough Colchester 5N 4W 12,13 a) Worthen, 1868, p. 11 Coal Member b) Wanless, 1956, p. 10 Francis Creek Shale Fulton Verrnont SN 1E 22 YE S\V, along a) Savage, 1927, p. 309; restricted by Wanless, Member Francis Creek 1929, P. 49, 89 b) wanless, 1929, p. 89; 1956, p. 10; 1957, geol. sec. 36, p. 203 J alie Creek Sandstone Fulton Vermont WE, along Jake Creek a, b) Wanless, 1957, p. 85, 89 and geol. see. 38, Member p. 204 I,owell Coa! Member LaSalle LaSalle SE SW a, b) Willman and Payne, 1942, p. 102-105, geol. sec. 33, p. 300 Oak Grove 1,imestone Ful ton Havana SW SE a) Wanless, 1931a, p. 184, 187, 192; present re- Member nort b) kanless, 1956, p. 10; 1957, p. 91 and geol. sec. 22, p. 197 Yurington Shale Member Knox Galesburg a) Wanless, 1931a, p. 184, 188, 192-from Pcor ms., 1930

L) Wan!ess. , 1956.,* n. 10 Shawneetown Coal Gallatin Shawneetown a) Present report. Previous name, No. 2A Coal Member (Harrison, 1951) 11) Present report (coal at 544 feet in Union Colliery diamond dri!l hole 28) Pleasantview Sandstone Schupler Beardstown Along Mill Creek ;I) Wanless, 1929, p. 90, attribute5 it to Sea- Member right ms., 1929 L)) Wanless, 1929, p. 90; 1956, p. 10; 1957, geol. sec. 5, p. 190 Kerton Creek Coal Falton Reardstown a) Ekblaw, 1930, p. 391; Wanless, 1957, p. 98, Member attributes it to Searight ms., 1929 11) Wanless, 1956, p. 10; 1957, p. 98 and geol. sec. 1, p. 189 Roodhouse Coal Member Greene Koodho~~se a) Siever, chart in Wanlesq, 1956 b\ Present report Summum (No. 41 Coal Ful to11 Vermont a) Wanless, 1931a, p. 82, 192 Member b) Wanless, 1956, p. 10; 1957, geol. sec. 39, p. 204 Hanover Limestone Greene Roodhouse a) Wanless, in Lamar et al., 1934, p. 84; Wanless, Member 1957, p. 101, attributes name to Van Pelt field notes b) Wanless, 1956, p. 10; 1957, p. 101 Cove1 Conglomerate LaSalle Ottawa a) Willman, 1939, p. 174-176 Member b) Willman and Payne, 1942, p. 116, footnote; Wanless, 1956, p. 10 Springfield (No. 5) Sangamon Springfield a) Worthen, 1883, p. 6. Named from subsurface Coal Member exposures in coal mines b) Wanless, 1956, p. 10 Harrisburg (No. 5) Saline Harrisburg In cod mines in the vicinity of Harrisburg a, b) Shaw and Savage, 1912, p. 7 Coal Member St. David Limestone Fulton Havana 6N 4E 17 SESF: a) Savage, 1927, p. 309, 313; Wanless, 1931a, Member p. 182-192 b) Wanless, 1956, p. 10; 1957, geol. sec. 21, p. 197 Canton Shale Member Ful ton Can ton 6N 4E 9 Center a, b) Savage, 1921, p. 240-241, and geol. sec., p. 241 Briar Hill (No. 5A) Union, Ky. Shawneetown In mines at DeKoven a) Glenn, 1913b, p. 38; Cady, 1919, p. 20; Coal Member Saline Eldorado 9s 7E 1926, p. 255 Equality b) Wanless, 1956, p. 10 TABLE1.-Continued

Group, formation, and member Part Original references to (a) name (b) type locality

Vermilionville Sandstone LaSalle Ottawa 32N 2E 9 SE a) Cady, 1915, p. 29 Member b) Wanless, 1956, p. 10 Big Creek Shale Member Fulton Canton 7N 4E Along Big Creek a) Savage, 1927, p. 309, 313,315 b) Wanless, 1957, p. 108 Herrin (No. 6) Coal i'Villinmson Herrin In mines in the vicinity of Herrin a) Worthen, 1870, p. 93, referred to No. 6 Coal; Member Shaw and Savage, 1912, p. 6 b) Shaw and Savage, 1912, p. 6 Brereton Limestone Fulton Glasford 7N 4E 1 SE NE, east bank of a) Savage, 1927, p. 309,313-315 Member Middle Copperas Creek b) Wanless, 1956, p. 10; 1957, p. 107, 111, 112, and geol. sec. 16, p. 195 Lawson Shale Member Bureau Annawm 16N 6E 24 Center a) Present report. Previous name, Sheffield Shale (Wanless, 1939, p. 102; 1956, p. 10; 1957, p. 112) b) Wanless, 1956, p. 10; 1957, p. 112 Jamestown Coal Member Perry Coul terville a) Bell et al., 1931, p. 3 b) Wanless, 1939, p. 17, 19, 88; 1956, p. 10 Conant Limestone Perry Coulterville a) Present report. Previous name, Jamestown Member Limestone (Bell et al., 1931, p. 3) b) Wanless, 1939, p. 17, 88; 1956, p. 10 Pokeberry Limestone Schuyler Beardstown a) Wanless, 1939, p. 17, 98 Member b) Wanless, 1956, p. 11; 1957, p. 113 and geol. sec. 3, p. 188 Copperas Creek Sand- Fulton Glasford Along Copperas Creek a) Savage, 1927, p. 309 stone Member b) Wanless, 1957, p. 114 Anvil Rock Sandstone Union, Ky. Shawneetown 1% miles NW of DeKoven a, b) Owen, 1856, p. 45 Member Banliston Fork Limestone Saline Harrisburg a, b) Cady, 1926, p. 261-262 (location incorrect) Member b) Present report Allenby Coal Member Williamson Harrisburg 9s 4E 24 NE NW in roadside a) Present report. Previous name, Bankston east of R. R. crossing Coal (Wanless, 1939, p. 14, 76) b) Present report. Kosanke, 1950, p. 79 Galum Limestone Member Perry Pinckneyville 6s 4W 13 Near center of N line a) Bell et al., 1931, p. 3 b) Wanless, 1956, p. 11 Danville (No. 7) Coal Vermilion Danville a) Bradley, 1870, p. 250-252 Member b) Wanless, 1956, p. 11

McLeansboro Group Hamilton McLeansboro a, b) DeWolf, 1910, p. 181; Weller, 1940, p. 36, footnote 13 Modesto Formation Macoupin Greenfield 12N 9W 16 to 17 NE SW SW to NE a, b) Present report Carlinville 10N 7W 35 SW SE; WxNE hTW Carlinville 9N 7W 2 NENW Piasa Limestone Member Jersey Brighton 8N 10W 25 EX a) Culver, 1925, p. 20 b) Wanless, 1956, p. 11 Farmington Shale Fulton Canton-Glas- 8N 4E Outcrops in Farmington a) Savage, 1927, p. 309 Member ford Township b) Wanless, 1956, p. 11 DeGraff Coal Member Perry Coulterville 5S 4W 21 SE cor. NE SW a) Present report-from Cady ms., 1950. Prev- ious name, 1st Cutler Rider Coal (Kosanke, 1950, p. 82-84) b) Present report-from Cady ms., 1950 Rock Branch Coal Member Macoupin Greenfield 12N 9 16 SW SW NW a, b) Present report. Previous name, Scottville Cod (Payne, 1942, p. 4) Pond Creek Coal Member Williamson West Frankfort 8S 3E 21 S\YSW NE NE a) Present report. Previous name, 2nd Cutler Rider Coal (Kosanke, 1950, p. 82-84) b) Present report-from Cady ms., 1950 Gimlet Sandstone Membe~Marshall Lacon 12N 9E 16 Nx SE, along a) Wanless, 1931a, p. 182, 183, 190, 192 Gimlet Creek b) Wanless, 1956, p. 11; 1957, p. 116 Athensville Coal Member Macoupin Greenfield 12N 9W 16 SENW SW a, b) Present report. Previous name, Upper Scottville Coal (Kosanke, 1950, p. 85) Lake Creek Coal Member Williamson West Frankfort 8S 3E 21 SVf7 SW NE NE a) Present report-from Cady ms., 1950. Pre- vious name, 3rd Cutler Rider Coal (Kosanke, 1950, p. 82-84) b) Present report-from Cady ms., 1950 Lonsdale Limestone Peoria Peoria 8N 7E 14 a, b) Worthen, 1873, p. 238 Member b) Wanless, 1957, geol. sec. 15, p. 194 (near type) West Franklin Limestone Posey, Ind. Henderson, 7S 12W 24 South-central ;I, 13) Collett, 1884, p. 61-62 Member Ky.-Ind. b) Wanless, 1956, p. 11 Sco ttville Limes tone Macoupin Greenfield 12N 9W 16 WsSW a) Payne, 1942, p. 4 Member b) Wanless, 1956, p. 11 Exline Limestone Member Appanoose, Centerville 67N 17W 6 SE a, b) Cline, 1941, p. 65-66 Ia. 'Trivoli Sandstone Peoria Glasford 8N 5E 3 SVIT a) Wanless, 19313, p. 182, 183, 190, 192 Member b) Wanless, 1956, p. 11; 1957, p. 121 and geol. sec. 8, p. 193 Chapel (No. 8) Coal Peoria Glasford 8hT 5E 3 SM7 a) Present report. Previous name, Trivoli (No. Member 8) Cod (Wanless, 1931a, p. 181-182, 190, 192) b) Wanless, 1956, p. 11; 1957, p. 121 and geol. sec. 8, p. 193 Cramer Limestone Peoria Glas ford 8N 5E 3 SW a) Present report. Previous name, Trivoli Mem her Limestone (Wanless, 1931a, p. 182, 190, 192) b) Wanless, 1956, p. 11; 1957, p. 121 and geol. sec. 8, p. 193 Carlinville Limestone Macoupin Carlinville ION 7W 35 SW SW a) Worthen, 1873, p. 290-301 Member b) Wanless, 1956, p. 11 Rurroughs Limestone Macoupin Carlinville 10N 7W 27 NW SW a) Weller, in Cooper, 19-26, p. 12, attributes this Member to Ball b) Wa_n_less,1956, p. 11; Ball, 1952, geol. sec. 17, p. 85 Womac Coal Member Macoupin Carlinville 9N 7\Y 2 NE NW a) Present report. Previous name, Macoupin Coal (Wanless, 1931b, p. 810-811) 13) Wanless, 1956, p. 11; Ball, 1952, geol. sec. 19, p. 85-86 Group, formation, and member County Quadrangle 1 T. R. Sec. Part Original references to (a) name (b) type locality 1 I I ------Macoupin Limestone Macoupin Carlinville 9 7 2 NE hT\l' a) Wanless. 1931b. v. 810-811 Member bj wanless; 1956, p.lll; Ball, 1952, geol. sec. 19, p. 85-86 New Haven Coal Member Gallatin New Haven 7S 1OE 19 NW a, bj Kosanke, 1950, p. 88-89

Bond Formation Bond Mt. Olive 7N 4W 29 SW NW a, b) Present report Bond New Douglas 6N 4W 6, 7 Creek along east edge Bond New Douglas 6N 4W 7 Cen. Sx, along Dry Fork Bond New Douglas 6N 5 24 East central along Flat Creek Montgomery Hillsboro 8N 2W 7 NENW SE Christian Pana 12N 1W 28 SENE Montgomery Nokomis ION 2W 3 NENE NE Shoal Creek Limestone Clinton Breese-Carlyle 3N 411: ,41o!lg Shoal Creek and a, b) Engelmann, 1568, p. 175, 177-183 Member vlclnlty Hall Limestone Member Bureau LaSalle 16N 11E 33 NW SW a) Weller, in Cooper, 1946, p. 12, attributes this to Willman ms., 1931 b) Wanless, 1956, p. 12-from Willman ms., 1931 McWain Sandstone Macoupin Carlinville a, b) Ball, 1952, p. 44 and geol. secs. 29, 33, 34, Member p. 89, 90, 91 Mt. Carmel Sandstone Wabash Mt. Carmel a, b) Worthen, 1875b, p. 52, 55 Member Sorento Limestone Bond New Douglas 6N 4W 6 NE NE fractional sec. a) Present report. Wanless, 1955-from !ii rnon Member ms., 1946 b) Present report-from Simon ms., 1946 Bunje Limestone Member Bond New Douglas a) Present report. Wanless, 1955-from Simon ms., 1946 b) Present report-from Simon ms., 1946 Flannigan Coal Member Hamilton 6S 5E Flannigan Township a, b) Newton and Weller, 1937, p. 9 Flat Creek Coal Member Bond New Douglas 6N SW 24 NE SE a) Present report. W anless, 1955-from Simon ms., 1946 b) Present report-from Simon ms., 1946 Keel Limestone Member Wabash Mt. Carmel IS 12W 8 NE (?) a, b) Worthen, 1875b, p. 55 Witt Coal Member Montgomery Hillsboro 8N 2W 7 NENW SE a, b) Present report-from Gluslcoter ms., 1958 Coffeen Limestone Montgomery Hillsboro 8N 2W 7 NE NW SF, a, b) Present report-from Gluskoter ms., 19.58 Member Millersville Limes tone Chris tian Pana 12N 1W 28 SENE a) Taylor and Cady, 1944, p. 22 Member 34 NWNW b) Payne and Cady, 1944, p. 12-1 3 Livingston Limestone Clark Marshall 11N 1 6 SENW a) Worthen, 1875b, p. 11-19 Member b) Wanless, 1956, p. 12 LaSalle Limestone 1,aSnlle LaSnlle a) Cady, 1908, p. 128-1 34 Member b) Wanless, 1956, p. 12 Mattoon Formation Outcro~sin counties- - of deeper Illinois Basin area of southeastern Illinois a, b) Present report Little Vermilion Lime- ~a~alli 33N 1E 11 SWSW a) Weller, in Cooper, 1946, p. 14-from Willman stone Member ms., 1931 b) Wanless, 1956, p. 12-from Willman ms., 1931 Friendsville Coal Member Wabash Sumner 1N 13W 13,24 a) Fuller and Clapp, 1904, p. 2 b) Kosanke, 1950, p. 89; Wanless, 1956, p. 12 McCleary's Bluff Coal Wabash Mt. Carmel 2s 13W 29 NW SW SE a, b) Present report; Kosanke, 1950, p. 89 Member Cohn Coal Member Clark Marshall 11N 12W 1 NE a, b) Newton and Weller, 1937, p. 18 Shelbyville Coal Member Shelby Shelbyville 11N 3-4E Outcrops and mines in the a) Broadhead, 1875, p. 169-171 vicinity of Shelbyville b) Kay, 1915, p. 215, 216 Merom Sandstone Sullivan, Hutsonville 7N 10W 7 a, b) Collett, 1871, p. 199 Member Ind. b) Wanless, 1956, p. 12 Opdyke Coal Member Jefferson 3s 4E Coal in vicinity of village a, b) Cady and others, 1952, p. 90-91 of Belle Rive (and Opdyke) Trowbridge Coal Member Shelby Mattoon 10N 6E 11 About cen. of S line a, b) Cady, 1948, p. 5, footnote 4 Calhoun Coal Member Richland Olney 2N 14W 6 NENE NE a) No6, 1934, p. 103, refers to this coal as "Cal- houn" (from o!d strip pit st Calhoun) b) Present report Bonpas Limestone Richland Olney a) Present report. Previous name, "Calhoun" Member Limestone (Weller, in Dunbar and Henbest, 1942, p. 27) b) Present report Omega Limestone Marion Salem a) Weller and Wanless, In Lamar et al., 1934, Member p. 128 b) Weller and Bell, 1936, p. 29-32; Wanless, 1956, p. 12; present report Shumway Limestone Effingham Effingham a) Weller, ii? Dunbar and Henbest, 1942, p. 28; Member Wanless, 1956, p. 12 b) Present report Effingham Limestone Effingham Effingham Creek along south line a, b) Wanless, 1956, p. 7, 12 Member b) Present report Bogota Limestone Jasper Sailor Springs a, b) Newton and Weller, 1937, p. 9 Member b) Present report Greenup Limestone Cumberland Toledo Cen. WxNNE a) Newton and Weller, 1937, p. 9, 26 Member b) Present report Gila Limestone Member Jasper Teutopolis NE SW a) Newton and Weller, 1937, p. 27 b) Present report Woodbury Limestone Cumberland Teu topolis sx SE a, b) Newton and Weller, 1937, p. 9, 28-30 Member Reisner Limestone J asper Greenup NE NE a, b) Present report. Previous name Newton Member Ls. (Newton and Weller, 1937, p. 9, 24-25) ILLINOIS STATE GEOLOGlCAL SURVEY R. I. 214

I hTamed Formation Area of state References Cyclothem j I Abingdon Spoon Western Wel!er, Wanless, et al., 1942 Babylon Abbott Western Wanless, 1931 a, p. 189-190, 192-193; 1957, geol. sec. 41, p. 189 Bankston Carbondale Southwestern and Weller, in Dunbar and Henbest, 1942, p. southeastern 16-18; Wanless, 1956, p. 11 Battery Rock Caseyville Southwestern and Weller, 1940, p. 37; Wanless ms., 1938 southeas tern Bogota Mattoon Southeastern Newton and Weller.. 1937,,,. P. 9., 19-24: Wan- less, 1956, p. 12 D. Brere ton Carbondale All Wanless. 1931a. L 180. 182-183, 190. 192 3 Briar Hill Carbondale Southwestern and Present 'report. ~reviousname; crab Or- sou theas tern chard Cyclothem, Wanless ms., 1938; Weller et al., 1942, p. 16. Brush Spoon Western Present report. Previous name, Middle DeLong Cyclothem, Wanless, 1931a, p. 188, 192; 1956, p. 9 Bunje Bond Southwestern Present report. Wanless, 1955, p. 1764- from Simon ms., 1946 Carlinville Macoupin Southwestern Ball, 1952, p. 34-37 Cohn Mattoon Eastern Newton and Weller, 1937, p. 9, 18-19 Co!bert Spoon Sou theas tern Wanless, 1956, p. 5, 9 Cutler Carbondale-Modesto Southwestern, south- Present report. Siever, in Wanless, 1956 eastern, and eastern Spoon Southeastern Weller, in Dunbar and Henbest, 1942, p. 16; Wanless, 1956, p. 10. DeLong Spoon Western Present report. Prev~ous name, Upper DeLong Cyclothem, Wanless, 1931a, p. 188, 192; 1956, p. 9 Delwood Abbott Southeastern Weller, 1940, p. '39; Wanless, 1956, p. 9 Flannigan Bond Southeastern Newton and Weller, 1937, p. 9-10 Flat Creek Bond Southwestern Present report. Wanless, 1955, p. 1764- from Simon ms., 1946 Gila Mattoon Sou theas tern Newton and Weller, 1937, p. 9, 27-28 Gimlet Modesto Western, northern, south- Wanless, 1931a, p. 182, 192 eastern, and eastern Greenbush Spoon Western Wanless, 1931a, p. 188, 192; 1956, p. 10 Greenup Mattoon Southeastern Newton and Weller, 1937, p. 9, 26-27 Grindstaff Abbott Southwestern and Butts, 1925, p. 44; Weller, 1940, p. 39 southeastern Hall Modesto-Bond Northern Weller, in Cooper, 1946, p. 12-from Will- man ms., 1931 Hermon Spoon Western Present report. Previous name, Lower DeLong Cyclothem, Wanless, 1931a, p. 188, 192; 1957, p. 73 Hicks Modes to Northern Weller, in Cooper, 1946, p. 12-from Will- man ms., 1931 James town Carbondale Southeastern Bell et al., 1931, p. 3; Wanless and Weller, 1932, p. 1007; Wanless, 1956, p. 10 D. Bond-Mat toon Northern Weller and Bell., 1936.>A 26-from Wil!man ms., 1931 Little Vermilion Mattoon Northern Weller, in Cooper, 1946, p. 14; Cooper, 1 p. 16-from Willman ms., 1931 Spoon-Carbondale Western Wanless, 1931a, p. 188, 192; 1956, p. 1957, p. 25, and geol. secs. 24, 25, p. Lowell Carbondale Northern Willman and Payne, 1942, p. 87, 102. and peol. sec. 33, P. 300 Lusk Caseyville Southeastern Weller,-1940, p. 361j7 Macedonia Ab bott-Spoon Southeastern Weller, 1940, p. 39, 40; Wanless, 1956, p. 9 Macoupin Modesto Southwestern Wanless, 1931b, p. 804, 811-812; Ball, 1952, geol. sec. 19, p. 85-86 Newton Mattoon Sou theas tern Newton and Weller, 1937, p. 9, 24-25 Pope Creek Abbott Western Wanless, 1931a) p. 189-190, 192 NAMED GYCLOTHEMS 53

1 I I Named Formation Area of state References Cyclo them , Pounds Caseyville-Abbo tt Southwestern and Wanless, 1929, geo!. sec. 4, p. 52, "Suite I"; southeastern 1957, p. 67-70; Weller, 1940, p. 38-39 St. David Carbondale All Wanless, 1931a, p. 182, 192; 1957, p. 102 and geol. sec. 21, p. 197 Seahorne Spoon Western and Wanless, 1931a, p. 188, 192; 1957, p. 76 and southwestern geol. sec. 30, p. 200 Seville Abbot t-Spoon Western Wanless, 1931a, p. 189, 192; 1957, p. 70 and geol. sec. 33, p. 201 Shoal Creek Modesto-Bond Southwestern, south- Wanless, 1931b, p. 804, 812 eastern, and eastern Shumway Mattoon Sou theas tern Weller, in Dunbar and Henbest, 1942, p. 28; Wanless, 1956, p. 12 Sorento Bond Southwestern Present report. Wanless, 1955, p. 1764- from Simon ms., 1946 Sparland Carbondale-Modesto Western and northern Wanless, 1931a, p. 182, 192 Stonefort Spoon Sou theastern Present report. Weller, 1940, p. 39; Wan- less, 1956, p. 9 (location in error) Summum Carbondale All Wanless, 1931a, p. 182, 192; 1957, p. 94 and geol. sec. 39, p. 204 Tarter Abbott Western Wanless, 1956, p. 9; 1957, p. 66 and geol. sec. 34, p. 202 Tonica Spoon-Carbondale Northern Present report. Previously called Liver- pool Cyclothem in northern Illinois (Will- man and Payne, 1942) Trivoli Modesto All Wanless, 1931a, p. 182, 192; 1956, p. 11; 1957, p. 121 and geol. see. 8, p. 193 Wiley Spoon Western Wanless, 1931a, p. 188, 192; 1956, p. 9; 1957, p. 79 and geol. sec. 42, p. 206 Witt Bond Southwestern Present report-from Gluskoter ms., 1958 Woodbury Mattoon Southeastern Newton and Weller, 1937, p. 9, 28-30 5 4 ILLINOIS STATE GEOLOGICAL SURVEY R. I. 214

TABLE3.-ALPHABETICAL LIST OF NAMESACCEPTED AND NAMESRESTRICTED OR ABANDONEDIN THIS REPORT (Fm. = Formation; M. = Member; 1,s. = Limestone; Ss. = Sandstone; Sh. = Shale)

Unit name I Formation or remarks Unit name Formation or remarks I I

Abhott Fm. Cheltenham Fire Clay Replaced by Cheltenham Clay Abingdon Coal M. Spoon M. Abingdon Cyclothem Spoon Coffeen Ls. M. Bond Absher Ls. ~k~lacedby St. David Ls. M. Cohn Coal M. Mattoon Allenby Coal M. Carbondale Cohn Cyclothem Mattoon Colbert Cyclothem Spoon Anvil Rock Ss. M. Carbondale Assumption Coal M. Spoon Colchester (No. 2) Athensville Coal M. Modesto Coal M. Carbondale Ava Shale Discontinued Conant Ls. M. Carbondale Babylon Coal Replaced by Manley Coal M. Copperas Creek Ss. M. Carbondale Cove1 Conglomerate Babylon Cyclothem Abbott M. Carbondale Babylon Ss. M. Abbott Crab Orchard Replaced by Briar Hill Bald Hill Coal Replaced by Mt. Rorah Coal Cyclo them Cyclothem M. Bankston Coal Replaced by Allenby Coal M. Cramer Ls. M. Modes to Bankston Cyclothem Carbondale Creal Springs Ls. M. Spoon Cuba Ss. Replaced by Vermilionville Bankston Fork Ls. M. Carbondale Ss. M. Battery Rock Coal Replaced by Gentry Coal Nl. Curlew Coal Replaced by O'Nan Coal M. Battery Rock Curlew Ls. M. Spoon Cyclothem Caseyville Battery Rock Ss. M. Caseyvil!e Curlew Ss. Replaced by Granger Ss. M. Bernadotte Ss. M. Abbott Cutler Coal Replaced by Danville (No. 7) Coal M. Bidwell Coal M. Spoon Cutler Cyclothem Carbondale-Modesto Big Creek Sh. M. Carbondale Cutler Ls. Replaced by Piasa 1,s. M. Bogota Cyclothem Mattoon Cutler Rider Goals Bogota 1,s. M. Mattoon First Replaced by DeGraff Coal M. Bond Fm. Second Replaced by Pond Creek Coal M. Bonpas Ls. M. Mattoon Third Replaced by Lake Creek Coal Boskydell Ss. Discontinued M. Brereton Cyclothem Carbondale Brereton LA M. Carbondale Cutler Ss. Discontinued Briar Hill (hTo.5A) Danville (No. 7) Coal M. Carbondale Coal M. Carbondale Davis Coal M. Spoon Briar Hill Cyclothem Carbondale DeGraff Coal M. Modes to Browning Ss. M. Spoon DeKoven Coal M. Spoon Brush Coal M. Spoon Brush Cyclothem Spoon DeKoven Cyclothem Spoon Bunje Cyclothem Bond DeLong Coal M. Spoon DeLong Cyclothem Spoon Bunje Ls. M. Bond Delwood Coal M. Abbott Burroughs Beds Replaced by Burroughs Ls. M. Delwood Cyclothem Abbott Burroughs Ls. M. Modesto Calhoun Coal M. Mattoon Delwood Ss. Replaced by Finnie Ss. M. "Calhoun" Ls. Replaced by Bonpas Ls. M. Drury Sh. M. Caseyvi!le "EffinghamH Beds Replaced by Efingham Ls. M. Canton Sh. M. Carbondale Efingham Ls. M. Mattoon Carbondale Fm. Exline Cyclo them Discontinued Carbondale Group Discontinued Exline Ls. M. Modesto Carlinville Coal Discontinued Carlinville Cyclothem Modesto Farmington Sh. M. Modesto Carlinville Ls. M. Modes to Finnie Ss. M. Abbott Caseyville Fm. First Cutler Rider Caseyville Group Discontinued Coal Replaced by DeGraff Coal M. Gha~el(No. 8) Coal Flanniaan Coal M. Bond ~lanniganCyclothen~ Bond M*. ' Modesto Cheltenham Clay M. Spoon Flat Creek Coal M. Bond NAMES ACCEPTED, RESTRICTED, OR ABANDONED 55

TABLE3.-Continued

Unit name Formation or remarks Unir: name Formation or remarks

Flat Creek Cyclothem Bond Lowel! Coal M. Carbondale Francis Creek Sh. M. Carbondale Lowell Cyclothem Carbondale Friendsville Coal M. Mattoon Lower DeLong Coal Replaced by Hermon Coal M. Galum Ls. M. Carbondale 1,ower DeLong Replaced by Hermon Gentry Coal M. Caseyville Cyclothem Cyclothem Lower Livingston Ls. Replaced by Livingston Ls. Gila Cyclothem Mattoon M. Gila Ls. M. Mattoon Gimlet Cyclothem Modesto Lusk Cyclothem Caseyville Gimlet Ss. M. Modesto Lusk Sh. M. Caseyville "Goose Lake" Clay Discontinued McCleary's Bluff Coal Mattoon McCormick Group Granger Ss. M. Spoon Macedonia Cy clothem Abbott-Spoon Grape Creek Coal Replaced by Herrin (No. 6: Coal M. McLeansboro Group Greenbush Coal M. Spoon Macoupin Cyclothem Modesto Greenbush Cyclothem Spoon Macoupin Ls. M. Modesto Greenup Cyclothem Mattoon McWain Ss. M. Bond Makanda Fm. Discontinued Greenup Ls. M. Mattoon Grindstaff Cyclothem Abbott Makanda Ss. (Lower) Replaced by Pounds Ss. M. Grindstaff Ss. M. Abbott Manley Coal M. Abbott Hall Cyc!othem Modesto-Bond Mattoon Fm. Hall Ls. M. Bond Merom Ss. M. Mattoon Middle DeLong Coal Replaced by Brush Coal M. Hanover Ls. M. Carbondale Harrisburg (No. 5) Middle DeLong Replaced by Brush Coal M. Carbondale Cyclothem Cyclo them Hermon Coal M. Spoon Millersville Ls. M. Bond Hermon Cyclothem Spoon Modesto Fm. Herrin Ls. Replaced by Brereton Ls. i\ Mt. Carmel Ss. M. Bond Mt. Rorah Coal M. Spoon Herrin (No. 6) Coal M. Carbondale Murphysboro Coal M. Spoon Hicks Cyclothem Modesto Murray Bluff Ss. M. Abbott Hicks Ls. Discontinued New Burnside Coal M. Spoon indiana Coal No. IIT Replaced by Seelegville New Haven Coal M. Modesto Coal M. New Haven Ls. Replaced by Shoal Creek Isabel Ss. M. Spoon Ls. M. Jake Creek Ss. M. Carbondale Newton Cyclothem Nlattoon Jake Creek Sh. Discontinued Newton Ls. Replaced by Reisner Ls. M. Jamestown Coal M. Carbondale No. 8 Coal Replaced by Chapel (No. 8) Jarnestown Cyclothem Carbondale Coal M. Jarnestown Ls. Replaced by Conant Ls. M No. 7 Coal Replaced by Dandle (No. 7) Coal M. Kerton Creek Coal M. Carbondale No. 6 Coal Replaced by Herrin (No. 6) Kewanee Group Coal M. Lake Creek Coal M. Modesto LaSalle (No. 2) Coal Replaced by Colchester (Ni No. 5 Coal Replaced by Springfield (No. 2) Coal M. 5) Coal hi. or Harrisburg LaSalle Cyclothem Bond-Mattoon (No. 5) Coal M. No. 5A Coal Carbondale LaSalle Ls. M. Bond No. 4 Coal Replaced by Summum (No. Lawson Sh. M. Carbondale 4) Coal M. "Liberty" Ss. Discontinued No. 2 Coal Replaced by Colchester Lick Creek Ss. Rep!aced by Battery Rock (No. 2) Coal M. Ss. M. No. 2A Coal Replaced by Shawneetown Litchfield Coal M. Spoon Coal M. Little Vermilion Cyclo- No. I Coal Replaced by Rock Island them iMattoon (No. 1) Coal M. Little Vermilion Ls. Oak Grove Beds Replaced by Oak Grove Ls. M. Mattoon M. Liverpool Cyclothem Spoon-Carbondale Oak Grove Ls. M. Carbondale Livingston Ls. M. Bond Omega 1,s. M. Mattoon Lonsdale Ls. M. Modesto O'Nan Coal M. Spoon 56 ILLINOIS STATE GEOLOGICAL SURVEY R. I. 214

TABLE3.-Continued I Unit name / Formation or remarks Unit name 1 Formation or remarks I I

Opdyke Coal M. Mattoon Stonefort Cyclothem Spoon "Ottawa" Clay Discontinued :tonefort Ls. M. Spoon Palzo Ss. M. Spoon Sub-Babylon" Coal Discontinued Piasa Ls. M. Modesto Summum (No. 4) Pleasantview Ss. M. Carbondale Coal M. Carbondale Summum C~clothem Carbondale Pokeberry Cyclothem Replaced by Jamestown Cy clothem Tarter Coal M. Abbott Pokeberry Ls. M. Carbondale TarterCyclothem Abbott Pond Creek Coal M. Modesto Tarter Ss. Discontinued Pope Creek Coal M. Abbott Third Cutler Rider Replaced by Lake Creek Pope Creek Cyclothem Abbott Coal Coal M. Tonica C~clothem Spoon-Carbondale Pope Creek Ss. Discontinued Pounds Cyclothem Caseyville-Abbott Tradewater Group Discontinued Pounds Ss. M. Caseyville Trivoli (No. 8) Coal Replaced by Chapel (No. 8) Purington Sh. M. Carbondale Coal M. Reel Ls. M. Bond Trivoli Cyclothem Modesto Trivoli Ls. Replaced by Cramer Ls. M. Reisner Ls. M. Mattoon Trivoli Ss. M. Modesto Reynoldsburg Coal M. Abbott Rock Branch Coal M. Modesto Trowbridge Coal M. Mattoon Rock Island (No. 1) Turner Cyclothem Replaced by Trivoli Coal M. Spoon Cyclothem Roodhouse Coal M. Carbondale Turner Ls. Replaced by Cramer Ls. M. Upper DeLong Coal Replaced by DeLong Coal M. St. David C~clothem Carbondale Upper DeLong Replaced by DeLong St. David Ls. M. Carbondale Cyclothem Cyclothem Scottville Coal Replaced by Rock Branch Coal M. Upper Livingston Ls. Replaced by Livingston Ls. Scottville Ls. M. Modesto M. Seahorne Cyclothem Spoon Upper Macoupin Cycle Discontinued Upper Scottville Coal Replaced by Athensville Coal Seahorne Ls. M. Spoon M. Second Cutler Rider Replaced by Pond Creek "Uticn" Clay Discontinued Coal Coal M. Vergennes Ss. M. Spoon Seeleyville Coal M. Spoon Sellers Ls. M. Caseyville Vermilionville Ss. M. Carbondale Seville Cyclothem Abbott-Spoon Wayside Coal Discontinued Wayside Ss. M. Caseyville Seville Ls. M. Spoon West Franklin Ls. M. Modesto Shawneetown Coal M. Carbondale Wiley Coal M. Spoon Sheffield Sh. Replaced by Lawson Sh. M. Shelbyville Coal M. Mattoon JViley Cyclothem Spoon Shoal Creek Cyclothem Modesto-Bond Willis Coal M. Abbott Wise Ridge Coal M. Spoon Shoal Creek 1,s. M. Bond Witt Coal M. Bond Shumway Cyclothem Mattoon Witt Cycl~them Bond Shumway Ls. M. Mattoon Sorento Cyclothem Bond Womac Coal M. Modesto Sorento Ls. M. Bond Woodburv Cvclothem Mattoon Woodbury L;. M. Mattoon Sparland (No. 7) Coal Replaced by Danville (No. 7) Coa! M. Spadand Cyclothem Carbondale-Modesto S~oonFm. springfield (No. 5) Coal M. Carbondale Stone fort Coal Replaced by Wise Ridge Coal M. REFERENCES

ASHLEY,G. H., 1898, The coal deposits of Indiana: CADY,G. H., et al., 1955, Subsurface geology ancl in Indiana Department of Geology and Natural coal resources of the Pennsylvanian system in Resources 23rd Annual Report, p. 1-1573. FVabash County, Illinois: Illinois Geol. Survey BALL,J. R., 1952, Geology and mineral resources of Rept. Inv. 183, 24 p. the Carlinville quadrangle: Illinois Geol. Sur- CAMPBELL,M. R., and LEVERETT,FRANK, 1900, Dan- vey Bull. 77, 110 p. ville, Illinois-Indiana: U. S. Geol. Survey Geol. BI-LL,A. H., BALL, C. G., and MCCABE,E. C., 1931, Atlas, Folio 67, 10 p. Geology of the Pinckneyville and Jamestown CLIXE, L. M., 1941, Traverse of upper Des Moines areas, Perry County, Illinois: Illinois Geol. and lo~7erMissouri series from Jackson County, Survey 111. Pet. 19, 22 p. Missouri, to Appanoose County, Iowa: Bull. BEMENT,A, 1910, The Illinois coal fields: in Year Am. Assoc. Petroleum Geologists, v. 25, no. 1, book for 1909: Illinois Geol. Survey Bull. 16, p. 23-72. p. 182-202. COLLETT,JOHN, 1871, Second Annual Report: In- BRADLEY,F. H., 1870, Geology of Vermilion Count): diana Geol. Survey, p. 190-240. in Geology and paleontology, vol. IV, p. 241- COLLETT,JOHN, 1884, 13th Annual Report, Indiana 265, Geol. Survey of Illinois. Dept. of Geology and Natural History, p. 45-70. COOPER,C. L., 1946, Pennsylvanian ostracodes of EROADHEAD,G. C., 1875, Geology of Shelby County: Illinois: Illinois Geol. Survey Bull. 70, 177 p. in Geology and paleontology, vol. IV, p. 163- Cox, E. T., 1875, Geology of Gallatin County: i?r 174, Geol. Survey of Illinois. Geology and paleontology, vol. VI, p. 197-219, BUTTS,CHARLES, 1925, Geology and mineral resources Geol. Survey of Illinois. of the Equality-Shatvneetown area: Illinois CULVER,H. F,., 1922, Note on the occurrence of Geol. Survey Bull. 47, 76 p. fusulinas in the Pennsylvanian rocks of Illinois: CADY,G. M., 1908, Cement-making materials in the Illinois Acad. Sci. Trans., v. 15, p. 421-425. vicinity of LaSalle: in Illinois Geol. Survey CULVER,H. E., 1925, Coal resources of District 111 Bull. 8, p. 127.134. (Western Illinois): Illinois Geol. Survey Min. CADY, G. H., 1915, Coal resources of District I Inv. 29, 128 p. (Longwall): Illinois Geol. Survey Min. Inv. 10, DESBOROUGH,G. A,, 1959, Correlation of the Bosliy- 149 p. dell Sandstone in southwestern Illinois: Bull. CADY,G. H., 1916, Coal resources of District Vl: Am. Assoc. Petroleum Geologists, v. 43, no. I I, Illinois Geol. Survey Min. Inv. 15, 94 p. p. 2720-2724. DEWOLE, F. IV., 1910, Studies of Illinois coal- C~DY,G. H., 1917, Coal resoul-ces of District 11 Introduction: in Year book for 1909, Illinois (Jackson County): Illinois Geol. Survey Min. Geol. Survey Bull. 16, p. 178-181. Inv. 16, 55 p. Drmors, E. P., 1951, Geology and coal resources of C:AL)Y, G. N., 1919, Coal resources of District V a part of the Pennsylvanian system in Shelby, (Saline and Gallatin counties): Illinois Geol. Moultrie, and portions of Effingham and Fay- Survey Min. Inv. 19, 135 p. ette counties: Illinois Geol. Survey Rept. Inv. CADY,G. H., 1921, Coal resources of District 1V: 156, 32 p. Illinois Geol. Survey Min. Inv. 26, 247 p. D~JNBAR,C. O., and HEXBEST,L. G., 1942, Pennsyl- CADY,G. 1-I., 1925, Structure of parts of north- vanian Fusulinidae of Illinois: Illinois Geol . eastern Williamson and western Saline counties: Survey Bull. 67, 218 p. Illinois Geo1. Survey Rcpt. Inv. 2, 20 p. (In EKBLAW,S. E., 1930, Channel deposits of the Pleas- cooperation with U. S. Geol. Survey.) antview sandstone in Western Illinois: Illinois CADY, G. H., 1926, The areal geology of Saline Acad. Sci. Trans., v. 23, no. 3, p. 391-399. county: Illinois Acad. Sci. Trans., v. 19, p. 250- ELIAS, h4. K., 1937, Depth of deposition of the Big 272. Blue (Late Paleozoic) sediments in Kansas: CADY,G. H., 1935, Classification and selection of Geol. Soc. America Bull., v. 48, p. 403-432. Illinois coals: Illinois Geol. Survey Bull. 62, ENGELMANN,HENRY, l8G8, Geology of Clinton and 354 p. Washington counties: in Geology and paleon- CADY,G. H., 1942, Analysis of Illinois coals: U. S. tology, vol. 111, p. 145-191, Geol. Survey of Bureau of Mines Tech. Paper 641, p. 1-23. Illinois. CADY,G. H., 1948, Analysis of Illinois coals: Illinois FULLER,M. L., and CLAPP, F. G., 1904, Patoka, Geol. Survey Bull. 62, Supplement, 77 p. Indiana-Illinois: U. S. Geol. Survey Geol. *4tlaL;, CADY,G. H., 1950, McLeansboro group in southern Folio 105, 12 p. Illinois: Illinois Geol. Survey, unpublished GLASS,H. D., POTTER,P. E., and SIEVER,RAYMOND, manuscript. 1956, Clay mineralogy of some basal Pennsyl- CADY, G. H., and others, 1952, Minable coal re- vanian sandstones, clays, and shales: Bull. ,4m. serves of Illinois: Illinois Geol. Survey Bull. 78, -4ssoc. Petroleum Geologists, v. 40, no. 4, p. 750- 138 p. 754. ILLINOlS STATE GEOLOGICAL SURVEY R. I. 214

GLENN,L. C., 1912a, The geology of Webster County: PAYNE,J. N., 1942, Structure of Herrin (No. 6) coal in Norwood, C. J., 1912, Report on the progress bed in Macoupin County, eastern Jersey and of the Survey for the years 1910 and 1911: Greene, southeastern Scott, and southern Mor- Kentucky Geol. Survey Bull., ser. 3, p. 25-35. gan and Sangamon counties: Illinois Geol. Sur- GLENN,L. C., 1912b, A geological reconnaissance of vey Circ. 88, 46 p. the 'Tradewater River region, with special ref- PAYNE,J. N., and CADY,G. H., 1944, Structure of erence to the coal beds: Kentucky Geol. Survey Herrin (No. 6) coal bed in Christian and Mont- Bull. 17, 75 p. gomery counties and adjacent parts of Fayette, GLUSKOTER,H. J., 1958, A stratigraphic study of the Macon, Sangamon, and Shelby counties: Illinois Shoal Creek-Millersville Interval in south- Geol. Survey Circ. 105, 57 p. central Illinois: State University of Iowa, un- POOR, R. 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SIXAM',E. Mi., 1921, New Athens-Okawville, Illinois: WANLESS,H. R., 1929, Geolom and mineral re- U. S. Geol. Survey Geol. Atlas, Folio 213, 12 11. sources of the Alexis quadrangle: Illinois Geoi. (published 1922). Survey Bull. 57, 230 p. SHAM',E. W., 1923, Carlyle-Centralia, Illinois: U. S. \VANLESS,H. R., 1931a, Pennsylvanian cycles in Geol. Survey Geol. Atlas, Folio 216, 10 p. TVestern Illinois: in Papers presented at the SHAW,E. W.,and SAVAGE,T. E., 1912, Murphysboro- quarter centennial celebration of the Illinois Herrin, Illinois: U. S. Geol. Survey Geol. Atlas, State Geological Survey: Illinois Geol. Survey Folio 185, I5 p. (published 1913). Bull. 60, p. 179-193. SHAW, E. W., and SAVAGE,T. E., 1913, Tallula- TVAWLESS,H. R., 1931b, Pennsylvanian section in Springfield, Illinois: U. S. Geol. Survey Geol. Western Illinois: Geol. Soc. America Bull., Atlas, Folio 188, 12 p. v. 42, p. 801-812. SEVER,RAE MOND, 1951, The Mississippian-Pennsyl- lranian unconformity in Southern Illinois: Bull. \\'ARLTSY,H. R., 1931c, The question of Pennsyl- Am. Assoc. Petroleum Geologists, v. 35, p. 542 vanian overlap in the Rock Island region. 581. Illinois Acad. Sci. Trans., v. 24, no. 2, p. 331- SIEVER,RAYMOND, 1956, Correlation chart of classi- 340. fication of the Pennsylvanian rocks of Illinoi~ \VANLESS,H. R., 1932, Depositional basin of he as of 1956: in Illinois Geol. Survey Circ. 217, Springfield (No. 5) coal in Northern Illinoir pl. 1. (abst.): Illinois Acad. Sci. Trans., v. 25, no. 4, $lr~vcR,RAYMOND, and POTTER,P. E., 1956, Source3 p. 153. of basal Pennsylvanian sediments in the Eastern TVANLESS,H. R., 1938, Stratigraphy of the Case? Interior Basin - 2. Sedimentary petrolog) : ville and Tradewater groups of Illinois: Illino 5 Jour. Geology, v. 64, no. 4, p. 317-335. Geol. Survey unpublished manuscript HRW-12, Yrnro~, J. A., 1946, Correlation studies of uppes 76 p. Pennsylwnian rocks in southwest-central Illi- TV~n~rsy,H. R., 1939, Pennsylvanian correlations nois: Univ. Illinois unpublished master's thesis, in the Eastern Interior and Appalachian coal 36 p. fields: Geol. Soc. America Spec. Paper 17, S~IITH,W. H., 1957, Strippablc coal reserves of Illi- 130 p. nois. Par1 1. - Gallatin, Hardin, Johnson, WANLESS,H. R., 1955, Pennsylvanian rocks of East- Pope, Saline, and MTilliamson counties: Illinois ern Interior Basin: Am. Assoc. Petroleum Ge Geol. Survey Circ. 228, 39 p. ologists Bull. v. 39, no. 9, p. 1753-1820. SMITH, TV. H., 1958, Strippable coal reserves of '\\T~~~~~~,H. R., 1956, Classification of the Pennsyl- Illinois. Part 2. - Jackson, Monroe, Perry, vanian rocks of Illinois as of 19.56: Illinois Randolph, and St. Clair counties: Illinois Ceol. Geol. Survey Circ. 217, 14 p. Survey Circ. 260, 35 p. ~VANLIW, H. R., 1957, Geology and mineral re- STEVENSON,TV. L., 1955, Pennsylvanian conodont~ sources of the Beardstown, Glasford, Havana, sf Illinois: Univ. Illinois unpublished master's and Vermont quadrangles: Illinois Geol. Sur- thesis, 56 p. vey Bull. 82, 233 g. TAYLOR,E. F., and CADY,6. I-I., 1944, Structure of \VANLESS,H. R., 1958, Pennsylvanian faunas of the the Millersville limestone in the north part of Beardstown, Glasford, Havana, and Vermont the Illinois Basin: in Progress reports on sub- quadrangles: Illinois Geol. Survey Rept. Inv. surface studies of the Pennsylvanian System in the Illinois Basin: Illinois Geol. Survey Rept. 205, 59 p. Inv. 93, p. 22-26. FV~n~css,H. R., and WI LLER, J. hl., 1932, Correla- tion and extent of Pennsylvanian cyclothems: THOMPSON,M. I>.. SHAVLR, K. H., and RIGGY,E. A,, 1959, Early Pennsylvanian fusulinids and ostra- Geol. Soc. America Bull., v. 43, (Dec.), p. 1003- cods of the Illinois Basin: Tour. Paleontology, 1016. v. 33, no. 5, p. 772. WELLLR,J. M., 1930, Cyclical sedimentation of thc Pennsylvanian period and its significance: Jour. UDDEN,J. A., 1912, Geology and mineral resources of the Peoria quadrangle, Illinois: U. S. Geol. Geology, v. 38, no. 2 p. 97-1 35. Survey Bull. 506, 103 p. ~VFLLER, J. M., 1931a, The conception of cyclicai UDDEN,J. A, and SHAW, E. W.,1915, Belleville- sedimentation during the Pennsylvanian pe- Breese, Illinois: U. S. Geol. Suwev Geol. Atlas, riod: in Papers presented at the quarter cen- Folio 195, 14 p. tennial celebration of the Illinois State Geolog- ical Sunvey: Illinois Geol. Survey Bull. 60. VAN DEN BERG,JACOB, 1956, Pennsylvanian strati- p. 153-179. pphy above the Shoal Creek limestone in Illinois: U11i17. Illinois unpublished master's ~VFLLTR,J. M., 1931b, Sedimesltarv cycles in the thesis, 6%; p. Pennsvlvanian strata - -4 reply: Am. Jour WANLESS,H. R., 1927, Stratigraphy and paleontol- Sci., 5th ser., \. 31, no. 124, p 31 1-329. ogy of the Pennsylvanian of northwestern Illi- WA YELLER, J. M.,1931c, Pennsylvanian o\ erlap in nois (abst.): Geol. Soc. America Bull., v. 38, United States (discussion): BuH. An. Assoc p. 133-134. Petroleum Geologists, 15. no. 6, p. 704-7'07. 60 ILLIATOIS STATE GEOLOGICAL SURVEY R. I. 214

TELLER, J. M., 1940, Geology and oil possibilities Chicago to Peoria: Illinois Geol. Survey un- of extreme Southern Illinois - Union, John- published manuscript HBW-4, 257 p. son, Pope, Hardin, Alexander, Pulaski, and WILLIAM,H. B., 1939, The Cove1 conglomerate, a Massac counties: Illinois Geol. Survey Repl. guide bed in the Pennsylvanian of Northern Inv. 71, 71 p. Illinois: Illinois Acad. Sci. Trans., v. 32, no. 2, WELLER,J. M., 1946, Stratigraphic summary: in p. 174-176. Cooper, C. L., 1946, Pennsylvanian ostracodes WILLMAN,H. B., and PAYNE,J. N., 1942, Geology of Illinois: Illinois Geol. Survey Bull. '70, and mineral resources of the Marseilles, Ot- p. 11-14. tawa, and Streator quadrangles: Illinois Geol. WELLER,J. M., and BELL,A. H., 1936, The geology Survey Bull. 66, 388 p. and oil and gas possibilities of parts of Marion ~VILLMAN, H. B., SWANN,D. H., and FRYE, J. C., and Clay counties, with a discussion of the 1958, Stratigraphic policy of the Illinois State central portion of the Illinois Basin: Illinois Geological Survey: Illinois Geol. Survey Circ, Geol. Survey Rept. Inv. 40, 54 p. 249, 14 p. WELLER,J. M., HENBEST,L. G., and DUNBAR,C. O., ~VORTHEN, A. H., 1868, Coal Measures and Lower 1942, Stratigraphy of the fusuline-bearing beds Carboniferous limestone: in Geology and pale- of Illinois: in Pennsylvanian Fusulinidae of ontology, vol. 111, p. 1-19, Geol. Survey of Illinois: Illinois Geol. Survey Bull. 67, p. 9-34. Illinois. WELLER,J. M., WANLESS,H. R., CLINE,L. M., and WORTI-IEN,A. H., 1810, Geology of Fulton County: STOOKEY,D. G., 1942, Interbasin Pennsylvanian in Geology and paleontology, vol. IV, p. 90- correlations, Illinois and Iowa: Bull. Am. 110, Geol. Survey of Illinois. Assoc. Petroleum Geologists, v. 26, no. 10, WORTHEN,A. H., 1873, Geology of Peoria County: p. 1585-1593. in Geology and paleontology, vol. V, p. 235- WELLER,J. M., et al., 1945, Geologic map of Illinois: 252, Geol. Survey of Illinois. Illinois Geol. Survey. WOWHEN,A. H., 1875a, Geology of Bond County: WELLER,S'ruAKT, 1906, The geological map of Illi- in Geology and paleontology, vol. VI, p. 128- nois: Illinois Geol. Survey Bull. 1, 26 p. 134, Geol. Survey of Illinois. WHITE, DAVID,1907, Report on field work done in WOKTHEN,A. H., 1875b, Geology of Clark, Wabash, 1907: in Year book for 1907, llli~~oisGeol. Edwards, Lawrence, and Richland counties: in Survey Bull. 8, p. 268-272. Geology and paleontology, vol. VI, p. 9-21, 37- WHITE,DAVID, 1909, Paleobotanical work in Illinois 65, Geol. Survey of Illinois. in 1908: in Year book for 1908, Illinois Geol. WOKTHEN,A. PI., 1883, Economical geology: in Survey Bull. 14, p. 293-295. Geology arid paleontology, vol. VII, p. 1-51, 14T~~~~~h~~JH. S., 1891, Geology of Washington Geol. Survey of Illinois. County: Arkansas Geol. Survey Annual Report WORTHEN,A. H., and ]ENGELMANN, HENRY,1866, for 1888, v. 4, p. xiii. Geology of Hardin County: in Geology [of WILLMAN,H. B., 1931, General geology and mineral Illinois], vol. I, p. 350-375, Geol. Survey of resources of the Illinois deep waterway from Illinois. GEOLOGIC SECTIONS

TYPEAND REFERENCESECTIONS OF FORMATIONS Geologic section 1 (modified from Lee, 1916, Geologic section 2.-Section exposed along p. 15-16).-Section measured from outcrops on the railroad cut of the Illinois Central Railroad the Illinois shore of the Ohio River between the from railroad tunnel, NW1/4 SW1/4 SEX sec. mouth of the Saline River and Gentry Landing 31, T. 11 S., R. 5 E., southward to NE1/4 SEX below Battery Rock, T. 11 S., R. 10 E., Shaw- NEX see. 18, T. 12 S., R. 5 E., Brownfield and neetown quadrangle, Hardin County. Harrisburg quadrangles, Pope County. Type section of the Caseyville Formation. Reference section of the Caseyville Formation. Thickness: (ft) Thickness: Pennsylvanian System Pmnsylvnnian Systm McCormick Group Casevville Formation McCormick Group ~&ndsSandstone Member Caseyville Formation Conglomerate, massive, coarse-bedded; Pounds Sandstone Member, light pebbles subordinate ...... gray, hard, medium to coarse- Conglomerate, pebbles very abundant . grained; numerous white quartz Clay shale, blue-gray to dark; increasingly nebhles: massive (754~feet ex- argillaceous below ...... hosed in cliJ) : .... Talus. Includes a thin coal near Casey- Shale, light gray, thinly lami- ville ...... nated, with sandy ironstone Sandstone, loose, dirty, ragged bedding nodules and bands; grades into Clay shale, blue ...... Shale, medium dark gray, similar Sandy shale and shaly sand ..... to above except for color; thin Clay shale ...... sandstone lenses ..... Clay shale with limestone bands 1 to 4 Gentry Coal Member, shaly in incl-es thick, 2 to 3 feet apart .... lower 2 to 5 inches .... Limy shale, blue, with four bands of dense Underclay, gray, silty, carbona- limestone 2 to 4 inches thick resembling ceous ...... ironstone ...... Limestone, dense, hard, like ironstone Shale, gray and dark gray, poorly when fresh, weathering platy and argil- laminated, silty; sandy in part laceous ...... Battery Rock Sandstone Mem- Shale, blue ...... ber, light gray, weathering buff, Talus ...... hard; quartz pebbles present; Sandstone, massive, contains coarse mica massive in upper part, less mas- and fine black specks at base .... sive in lower part. .... Slate, black, sandy ...... Coal, at one point 8 inches thick; Slaty sand in thin sheets, dark, carbona- unit commonly consists of 2 to ceous ...... 4 inches of coal, shnle, and sand- Shale, black, sandy ...... stone conglomerate at base of Not exposed ...... sandstone above or occurs as Gentry Coal Member ...... stringers in sandstone ... Talus ...... Lusk Shale Member Sandstone, loose, irregular in texture . Shale, sandy, interbedded with Talus ...... shaly sandstone and thin- Sandstone, slabby, dense, fine-grained, bedded sandstone. Sand- ripple-marked ...... stone is fine grained; occa- Talus ...... sional quartz pebble ... Sands tone .....,....a Carbonaceous, clayey "smut" Talus,probablyshale...... band...... Shale ...... Sandstone and shale; sand- Battery Rock Sandstone Member stone, light gray, conglomer- Sandstone in thin beds probably alter- atic with quartz pebbles, In- nating withshaly sandstone . . , terbedded with gray, sandy Talus ...... shale and shaly sandstone; Conglomerate ...... some benches of sandstone Lusk Shale Member massive, some benches more Sandstone, dirty and slabby .... thinly bedded; quartz peb- Talus ...... bles present as in sandstones Sandstone, massive ...... above. Area of maximum Slaty sand ...... known development ... Ta!us ...... Clay, greenish gray, with brown iron-staining in part; soft and Total 511+ plastic when wet; occasional shale fragments and light Mississippinn System gray, dense, hard, angular ILLINOIS STATE GEOLOGICAL SURVEY R. I. 214

Thickness: (ftj (in) Thickness: ('t) (in) masses of sandstone. Grades root remains and ironstone con- into small pockets of clay cretions; stained yellowish filling depressions in the top brown; wel! indurated ... 3 of the limestone .... 1 3 Shale, medium to light olive-gray, silty ...... 3 Total 372 9f Shale, dark gray, silty to sandy; slightly. micaceous; ironstone .kfississippian System concret~ons ...... 25St Grindstaff Sandstone Member, Chester Series light gray, massive, medium- Kinkaid Limestone, gray, argilla- ceous in part, foss~l~ferous,mas- grained, fairly clean quartz sive; in benches up to 18 inches sand ...... 50=t thick with occasional thin shalv Conglomerate of shale, siltstone, band up to 6 inches thick; ii- and some sandstone; contains regular beds of chert 2 to 8 some large blocks several feet inches thick and occasional across ...... 30& rounded chert masses ...12=t Total 277 7=t Geologic section 3.-Exposures in cuts along the Illinois Central Railroad, NWX see. 5, T. 11 S., R. 5 E., to north end of railroad tunnel, Geologic section 4 (modified from Wanless, 1957, geologic section 32, p. 201).-Roadcut, SEX SW% see. 19, T. 11 S., R. 5 E., Harris- railroad cut of T. P. and W. Railroad, and ra- burg quadrangle, Pope County. vine, SEX see. 22, T. 6 N., R. 1 E., Vermont Type section of the Abbott Formation. quadrangle, Fulton County. Thickness: Type section of the Spoon Formation. Penmyhanzan System Tt5ickne.r~: (.ft) (in) McCormick Group Penn ~jlvanianJ'ystem Abbott Formation Murray Bluff Sandstone Member Kewanee Group Sandstone, yel!owish gray, mi- Carbondale Formation caceous, mealy, massive . . Francis Creek Shale Member, Conglomerate (ironstone and gray to olive-gray ... 18 shale pebbles in sandy ma- Cnlchester (No. 2) Coal ~ernbkr I 11 trix), reddish brown to rusty with some codified logs or wood ...... Sandy, shaly material at un- 3oon Formation conformable contact ... Underclay, light gray, noncalcare- Shale, bony or coaly .... ous ...... Delwood Coal Member, somewhat Underclay, rust hrown, calcare- shaly and bony, but fairly ms; selenite crystals ... bright ... . . *. Browning Sandstone Member Clay, blue-gray, f;ard, sandy, Sandstone position; shale, silty poorly bedded, with carbona- and sandy, gray; upper 8 ceous root remalns; micaceous inches gray to red .... Clay, light gray, sandy, with ir- Shale, dark gray, thin-bedded . . regular fracture;. some carbona- Shale,rustbrown ..... ceous root remains .... Shale, black, carbonaceous . . Sandstone, fine-grained, poorly Abingdon Coal Member, coaly bedded, bluish gray, dense, streak ...... hard ...... Underclap, dark brown ... Shale, liiht to medium bluish Underclay, sandy, light gray . . gray, sandy; sandstone layers Iimestone concretionq, brown and ironstone bands ... and . rust brown, large; dis- Finnie Sandstone Member; continuous ...... brownish gray, thin-bedded, Isabel Sandstone Member, gray . medium-grained ..... Shale, medium gray .... Shale, black, silty, hard. .. Shale, dark gray, locally coaly . Shale, greenish gray, hard. silty Underclap, gray, mottled yellow with small ironstone nodules or and rust brown ..... concretions ...... Wiley Coal Member, soft ... Shale, black, hard, massive Underclay, dark gray .... Willis Coal Member, rather tkn-' Underclay, light gray .... bedded, bright luster ... Seahorne Limestone Member, Shale, black with thin coaly lenses light gray, in discontinuoui Underclay, medium olive-gray, band of large concretions . . hard, sandy, with cartmnaceous Concealed ...... TYPE AND REFERENCE SECTIONS 6 3

Thick~ess: (ft) (in) Geologic section 5.-Compiled from expos- Underclay, light gray .... 1 ures at the following localities: Shale, carbonaceous .... 2% Geologic section SA-abandoned strip mine pit on south- DeLong Coal Member facing highwall, about 500 feet north of the south edge Shale; contains canneloid coal % of the NWX NEX sec. 21, T. 10 S., R. 5 E., Harrisburg Underclsy, light brownish gray . 1 6 quadrangle, Saline County. Shale, dark blue-gray .... 6 Geologic section SB-along small stream draining Brush Coal Member abandoned strip mine pit from north of east-west road Clay, coaly ...... 1 to about % mile south of this road, E% NWX sec. 21, Underclay, light gray ... 5 T. 10 S., R. 5 E., Harrisburg quadrangle, Saline County. Shale, !ight gray ..... 4 Geologic s~ction5C-east face of Creal Springs quarry, NEX SEX SEX sec. 25, T. 10 S., R. 3 E., and ravine Sandstone, reddish brown ... 1 on north-facing slope south of Sugar Creek, NWX Shale, dark gray, thin-bedded; SWX SWX sec. 30, T. 10 S., R. 4 E., Marion quad- selenitecrystals ..... 3 rangle, kvilliamson County. Hermon Coal Member, coaly Geologic section jD-abandoned hillside strip mine and streak ...... % ravine to the north of the mine, center SEX SWX sec. Underclay, medium to dark gray I 6 5, T. 11 S., R. 4 E., Marion quadrangie, Johnson Shale, dark gray; ironstone con- County. cretions ...... 1 h Seville Limestone Member, argil- Reference section of the Spoon Formation in South- laceous, light blue-gray, un- ern Illinois. Geol~gicsection 5C includes type out- evenly bedded; weathers platy; crop of Creal Springs Limestone Member. Geologic fossiliferous; pinches out to section 5D includes type outcrop? of New Burnside and south ...... 3 4 Bidwell Coal Members. Shale, carbonaceous, black, soft 3 Geologic section 5A Rock Island (No. 11 Coal Mem- ber ...... 2%-3 Thickness: Clay, dark gray to black, very Pennsylvanian Sjjstem carbonaceous; some semblance Kewanee Group of bedding near top; occasional Spoon Formation vitrain streak up to 1/16 inch Palzo Sandstone Member thick; grades into .... 3 Covered interval with large Underclay, medium gray hecom- sandstone blocks on surface. ing lighter gray downward, yel- The Pnlzo reaches a maxi- lowish gray in part, firm, non- mum known thickness of ca!cxreous; carbonaceous root about 40 feet in this area . remains; occasional slightly sil- Shale, greenish grajr, thicknes ty zone in bottom 8 inches; uncertam ...... qrades into ...... 1 7 Shale, black, slaty ..... - Shale, dark gray to black, fissile Clay, light to medium gray with in prt; very carbonaceous in abundant vellowish iron-stain- bottom 2 inches ..... ing on fracture surfaces, plastic Coal, soft, top 4 inches much when wet, noncalcareous, very weathered ...... finely silty; some zones very Underclay, light gray, slip-frac- hard; where weathered the iron tured; numerous carbonaceous material covers the surface in root remains; micaceous; rela- small clay-ironstone plates and tively firm; grades into ... flakes up to 1/16 inch thick; Clay increasingly sandy down- gradesinto ...... 4 2 --- -.- - ward. May be weathered sand- stone in lower part .... Total 64 5% Sandstone, light-gray, weather- ing brown, medium-grained, micaceous, dirty, massive, in McCormick Group benches up to 1% feet thick; thinstowest...... Abbott Formation Ciltstone, gray to dark gray, well Bernadotte Sandstone Member laminated, carbonaceous; con- Siltstone, light gray, weather- tains thin, light gray sandstone ing whitish; very fine-grain- lenses and laminae; tends to ed, noncalcareous; some fine- he massive in bottom 2 feet ly disseminated carbona- Shale, gray to dark gray, slightly ceous debris; considerable silty becoming less silty down- ~ellowishto reddish brown ward, well laminated ... iron - s tainmg; very argil- Shale, dark gray to black, rela- laceous; becomes somewhat tive!~soft and earthy ... coarser grained downward; DeKoven Coal Member, normal- bnse concealed .... I 4f ly bright-banded ..... ILLINOIS STATE GEOLOGICAL SURVEY R. I. 214

Thickness: (ft) (in) Thickness: Underclay, light gray (slightly 8 to 11 feet well exposed in a darker gray in top 2 inches), series of abandoned small quar- silty, soft, friable; numerous rles. Lower 7 feet poorly ex- carbonaceous root remains . . 1 9 posed but mostly interbedded Clay, light greenish gray, silty, sand and shzle ..... friable ...... 2 3 Shale, medium to dark gray, soft, Sandstone, gray, weathering olive- weathered ...... green; dark gray shaly partings Shale, black, fissj!e. Observed in and bands. Sandstone is dirty, place on east side of abandoned massive, cross-bedded, and var- wagon road. Base concealed . ies in thickness from 6 to 9 Shale, gray to dark gray, mostly inches ...... covered ...... Shale, medium gray, becoming Stonefort Limestone Member, dark gray to black in the bot- weathers light tan to buff; blu- tom 3 inches; iron-stained on ish gray on fresh surfaces, dense, partings, thinly laminated . . 4 fossiliferous ...... Shale, black, fissile ..... 1 10 Covered interval appears to be Davis Coal Member, normally mainly gray shale, with some bright-banded ..... 3 6 black shale (position uncertain) Underclay ...... 1rf Shale, gray, fairly well to poorly bedded, soft, iron-stained, poor- Total 95 4 Iv ex~o~ed...... wise ~id~eCod Member, very badlvweathered. .... (Geologic sections 5A and 5B overlap) underday, light gray with con- spicuous yellow mottling; slip- Geologic section 5B fractured, relatively firm; car- bonaceous root remains, not Davis Coal Member, hard and wellexposed ...... fairlybright ...... Siltstone, light gray with yellow- Underclay, medium brownish gray ish oxidation mottling, argilla- Underclay, light gray with pur- ceous and fine-grained, fairly plish cast, not bedded, slicken- well bedded ...... sided, silty; carbonaceous root Shale, black, carbonaceous, fair- remains ...... ly soft, fissile in part .... Underclay, light gray, stained Underclay, medium gray, shaly light yellow-brown along joint and silty, fairly hard, some surfaces, slightly silty; carbo- carbonaceous root remams; naceous root remains. ... gradesinto ...... Clay, light gray, permeated with Shale, gray, well bedded, fairly iron oxides whose weathering hard; contains some ironstone forms hard bands extending out concretions up to G by 18 through the clay; grades into . inches in lower 2 feet .... Shale, light olive-gray, poorly Mt. Rorah Coal Member bedded, silty to sandy; sand- Coal, upper 434 inches finely stonelenses ...... banded in units %-inch thick; Siltstone or sandy shale, poorly lower 10 inches blocky and bedded, streaked with iron bright ...... along joint surfaces, poorly Clay, light brownish gray consolidated ...... wexthering yellow, shaly, Sandstone, light olive-gray, fine- much oxidized, abundant grained, thin-bedded; contains plant debris; unit thins to minute mica flakes .... north (11 inches to 1 inch) . Sandstone, light gray, weathering Coal, blocky, shaly, and brownish gray, rather fine- to weathered ...... medium-grained, massive. Base Underclay, gray becoming light concealed ...... 4 gray downward with much iron stain, s!ip-fractured, nunier- Total . 18 8 ous carbonaceous root remains; noncalcareous, soft, blocky . , (Relationship of geologic sections 5B and 5C uncertain Shale, light gray with much yellow within a few feet) iron-stained weathering, silty, poorly laminated .... Geologic section 5C Shale, medium gray with brown ~ron-sta~ningon numerous part- Sandstone, gray on weathered sur- ings, silty, fairly well laminated, faces, bufT on fresh fractures, carbonaceous; grades into . . medium- to fine-grained, even- Shale, gray, thinly and fairly well bedded with some beds up to 5 laminated ...... feet thick, minor shale and Interval not well exposed. Prob- siltstone partings. Generally ably gray shale similar to above TYPE AND REFERENCE SECTIONS 6 5

Thickness: (ft! (in) Geologic section &-Compiled from expos- Creal Springs Limestone Member, ures at the following localities: weathers reddish buff, dense, hard, aod fos4liferous; thins to Geologic section 6A-(modified from Wanless, 1957, north (4 to 24 inches thick) . . 1 geologic section 16, p. 195) high east bank of Middle Shale, gray, very silty, fairly soft Copperas Creek and roadcut a little to the north, SEX hut well bedded; ironstone con- NEX sec. 1, T. 7 N., R. 4 E., Glasford quadrangle, cretions up to 4 inches long in Fulton County. upper part; some fairly persist- Geologic section 6B-ditch and bank on the south side ent fine-grained sandstone of the gob road and east of the C. R. and Q. Railroad, benches up to 6 inches thick SW corner sec. 21, T. 8 N., R. 3 E., Canton quadrangle, marked. by strong ferruginous Fulton County. iron-staining ...... 5 Geoloxic section 6C-cutbank on south side of Coal Granger Sandstone Member, light Creek and ravine about 200 feet to the south, ExhTEx gray to buff, .generally fine- to NWX sec. 20, T. 8 N., R. 3 E., Canton quadrangle, very fine-grained with a few Fulton County. shale partings; abundant small- scale cross-bedding; becomes coarser grained with thicker Type section of the Carbondale Formation. Geologic beds toward base; at creek level section 6A includes type outcrop of Brereton Limestone is a 5-foot massive bed. Esti- Member. mated thickness of the sand- stone in this area is 60 to 70 feet 40 Geo'logie section 6A Total 133 Thickners: (ft) (in) 4+ Pmmyluanian System McLeansboro Group (May be overlap between geologic sections 5C and 5D) ~~d~~~~ ~~~~~~i~~ Farmington Shale Member, gray, Geologic section 5D soft; weathers buff .... 4 6 Granger Sandstone Member Shale, black, soft to hard ... 3 Sandstone, light gray, fine- grained; irregularly inter- Tota1 bedded with 10 to 15 percent - shale partings; partings .more Kewanee Group numerous in upper portion . 6 Carbondale Formation Conglomerate, gray, sandy, and Danville (No. 7) Coal Member . ferruginous; contains x-to Underclay, light to dark gray, 1-inch well rounded sand- ~lastic...... stone and shale pebbles . . 6 ~idercla~,light gray .... Shale, gray, sandy, interbedded Underclay, slightly sandy, cal- with carbonaceous shale . . careous, with limestone con- New Burnside Coal Member, nor- cretions ...... mally bright-banded (seen in Copperas Creek Sandstone Mem- abandoned strip mine) ... ber Covered; with some sandstone Sandstone, gray, argi!laceous; float shown in lower 3 feet: . . 6 weathers redd~shbrown, mas- Shale, gray, sandy ..... 6 slve ...... Conglomerate, very ferruginous Sandstone, buff to gray, fine- and hard. red color cons~icuous: grained, shaly in upper part sandstonk, shale, and somd and massive below. ... chert pebbles up to 3 inches in Lawson Shn!e Member, gray, soft, diameter embedded in a sandy with small ironstone concretions matrlx; disconformable with Shale, yellow-gray, calcareous, coalbelow ...... fossiliferous (crinoid stems and Bidwell Coal Member brachiopods)...... Coa!, blocky, beds %- to 1-inch Brereton Limestone Member, thick interbedded with ap- gray, in 2 benches, the upper proximately 25 percent coaly bench 2 feet 2 inches thick and shale ...... 5 more massive than the lower . Coal, blocky, bright; varies Shale, light gray; weathers buff; from % to 1% inches ... 1 soft, with smnll b!ack calcare- Clay, gray ...... 1 ous and ~vriticconcretions . . Coalp shale ...... 124 Shale, blac'k- to dark gray ... Coal, blocky, bright .... Herrin (No. 6) Coal Memher Shale, coaly ...... coal,'irregular masses of mica- Shale. coalv and verv fissile . . ceous siltstone at to^ ... Clay, light iray, saidy, badly Coal ...... 11% weathered; base concea!ed . . 3f Shale, medium gray, laminated . %-% Coal ...... 11% Total 49 8 Clay, medium blue-gray, "blue- band" ...... 2% 66 ILLINOIS STATE GEOLOGICAL SURVEY R. I. 214

Thickness: (ftj (in) Thickness: (ft) (in) Coal ...... 3% Summum (No. 4) Coal Member, Pyrite ...... 34 weathered, thickness variable . 2% Co a1 ...... 5% Underclay, light gray; base con- Clay, dark gray ..... % cealed ...... 8+ Coal ...... 1 34 Underclay, noncalcareous, dark Total 23+ blue-gray ...... I Underclay, light gray .... 6 Underclay, calcareous, light gray . 2 6 Vermilionville Sandstone Mem- (Estimated 5 feet between geologic sections 6B and 6C) ber, greenish gray, mottled brown, hard, lower part calca- Geologic section 6C reous ...... 3 Canton shale Member Pleasantview Sandstone Member, Shale, medium gray, slightly brownish gray, badly weather- sandy ...... 4 ed, very soft ...... Shale, light greenish gray; con- Purington Shale Member, light tains sma!l ironstone concre- to medium gray with olive cast tions and limestone joint- in part, thyn-iedded, smooth; fillings; base concealed . . 8 contains numerous thin bands and lenses of sideritic material; Total 65 6 top slumped and covered . . Oak Grove Limestone Member Thestone, medium gray with vellowish brown to reddish (Probably up to 20 feet of shale between geologic sec- brown oxidation coating, tions 6A and 6B) dense to finely crystalline, argillaceous, hard, very nod- Geologic section 6B ular in appearance, quite fossiliferous (main1y brachi- Canton Shale Member, gray, opods), much weathered in weathered,soft ..... part ...... Shale, black, slaty ..... Shale, light to medium gray be- Shale. black. carbonaceous . . coming darker downward springfield (NO. 5) Coal Member, with an olive-gray to redd!sh normally bright-banded ... brown cast in part; contams ~nderclai,meaium to dark gray; some iron-staining on verti- weathers light gray with yellow cal fractures and abundant staining;.grades into ... small selenite crystals Shale, medium to dark gray, some throughout; top thin-bedded yellow and brown staining, oc- and nssile, becoming well casional coaly streak. ... bedded and thicker bedded Shale, gray, olive cast, plactic downward; bottom 1 foot when wet ...... much harder ..... Clay, weathering yellowish brown, with hard calcareous nodules . Limestone, brownish gray, Limestone, very argillaceous, ir- dense, very hard, fodiferous regular nodules in clay matrix . (n u m e r o u s brachiopods); Clay, gray, weathering olive-drab; thickness varies from 2 to 7 large, dark, rounded concre- inches; appearing somewhat tions in lower part associated nodular in part .... with Cove1 Conglomerate-like Shale, medium gray, very cal- material; associated concretions careous. fossili ferous: con- up to 6 inches thick and up to tains a6undant limy iodules 18 inches long containing ma- up to 1% inches indiameter; rine fossils, pitted surfaces represents transition zone (algal?), and phosphatic nod- from the overlying limestone ules ...... to the underlying shale . . Shale, dark gray, mottled with Shale, medium to dark gray, medium gray; becomes lighter medium-grained, quite hard, toward the top ..... fairly well bedded, calcare- Hanover Limestone Member. ous, almost a very argilla- medium gray, dense, hard, with ceous limestone in some marine fossils: bottom 6 inches zones, fossiliferous (pelecy- nodular but massive bench; pods, crinoid stems) ... upper 3 to 4 inches thin-bedded Sideritic. band, slightly calca- with thin, discontinuous inter- reouslnpart ..... beds of dark gray shale; thick- Shale, medium dark gray, very ness variable ...... carbonaceous in part, smooth, Shale, medium to dark gray; fairly well and thinly bedded, thickness variable .... rather weak and crumbly. . ANL) KEFEKEATCL; SECTIONS 6 7

Thickues.~: (jt ('I Geologic section 7A Limestone, gray, argillaceous, dense, fossiliferous; thick- Thickness: (J't) (in) ness varies from 4 to 16 inches IJcizwsyltraniciul Syst~nz within ;I distance of 5 feet. . 10 McT,eansboro Group Shale, dark gray, thin-bedded, Bond Formation soft, somewhat weathered . . 4 Shoal Creek Limestone Member Shale, black, hard, fissile; oc- Limestone, light gray, dense, casional phosphatic nodule; poorly bedded, nodular, some signs of weathering on abundantly fossili ferous, fractures; somewhat softer in grades into ...... 7 upper part...... I ,i mestone, green-gray, more massive in upper than in Shale, black, hard, fissile; numer- lowerpart ...... I 6 ous phosphatic nodules up to Shrtle, gray, ca!careous, soft, 1% inches across; pimply ap- fossili ferous ..... 1 1 pearance in part; tends to be 7 massive ...... 1 Total 9 7 Shale, very dark gray to black, hard; small phosphatic nodules up to inch across .... 2 NIodesto Formation Colchester (No. 2) Coal Member Shale, bituminous, locally cal- blocky, hard; approximate!^ 3 careous, subcuboidal jointing; inches exposed above water contains worm borings ... I level; bottom below water level; Shnle, black, somewhat calcare- lenses out within 6 feet to the ous, hard; contains condonts, northeast ...... 5+ fish sc?le$ and spines, and ocl cas~onalflakes of gypsum . . 2 Total 46 11 $ Shale, black, calcareous, hard, -- poorly- - bedded, fossiliferous . Shale, brownish gray, calcareous, fossiliferous ...... Spoon Formation Shnle, dark gray, clayey, calcare- Underclay, light to medium gray ous, rparsely fossiliferous; lime- with some yellowish staining stone concretions up to 4 inches in the top 1 foot, relatively thick and 12 inches across con- hard and firm, plastic when wet; taining pyritized fossils occur contains carbonaceous root re- near the top ...... 2 2 mains; bottom concealed . . 2 6+ Shale, light gray, clayey, noncal- careous, iron-stained ... 2% Clay, light to medium blue-gray, Geologic section 7,Compiled froin expos- noncalcareous, poorly bedded, ures at the following localities: some suggestion- - of lamination . 8 $5 Clay, medium gray, harder than Geologic sectiorr 7A (modified from Ball, 1952, geologic the above, slightly calcareous . section 19, p. 85)-outcrops along small tributary of Limestone, medium gray, shaly, Macoupin Creek in SWX SEX sec. 35, T. 10 N., K. fossiliferous ...... 7 W., and NEM NWM sec. 2, T. 9 N., R. 7 \Y.,Car- Shale, gray, siightly calcareous . linville quadrangle, Macoupin County. Limestone, very fossiliferous . . Geologic section 7B (modified from Ball, 195?., geologic Shale, medium gray, slightly cai- section 15, p. 84)-outcrop along west bank of Macou- careous; contains marine fossil> pin Creek, WS NEX NWX sec. 35, T. 10 n'., K. 7 and carLonaceous plant mater- \V., Carlinvijle quadrangle, Macoupin County. ial ...... Limestone, blue-gray, highly fos- Geologic section 7C-along northwest-f'owing tributarj ~ilifero~i \; contains ,li;rurchi.conin to Turner Creek from SWM SWM SEX sec. 7., T. 12 orWo?-th~nin(?)..... N., R. 8 W., to NEM SEX SIT% sec. I, T. l? N., R. Shaie, blue-gray, thin-bedded, fo4- 9 W., Greenfield and Jacksonville quadranp.les, Macorr- si!iferous; contams iVuculurrn pin County. and carbonaceous plant ma- Geologic section 7D-along Rock Branch from hridge terial ...... in NEM SWM SWX sec. 16, downstream into NEM Limestone, medium to dark blue- sec. I?, T. 12 N., R. 9 W.,Greenfield quadrangle, gray; contams Asiculoperten, Macoupin County. ,Vful-chisonia, Beller-ophon . . Shale, light blue-gray, thin-bed- Type section of the Modesto Formation. Geologic ded ...... section 7A includes type outcrops of hlacoupin Lime- Limestone, medium to dark blue- stone Member and Womac Coal Member, Geologic 7D gray, subcrystalline, moderate- includes type outcrops of Scottville Limestone Mem- ly fo~siliferous,with .i'rictilop~r- ber, Athensville Coal Member, and Rock Branch tenandgastropod\ .... Coa! Member. Shale, blue-gray, thin-bedded . . fi8 ILLIATOIS STATE GEOLOGICAL SURVEY R. I. 21.J

Thickness: Thickness: Limestone, dark blue-gray, fos- Shale, dark gray, slightly calcar- siliferous ...... eous, fairly hard, unevenly Shale, blue-gray...... bedded; contains some brown- Limes tone ...... ish gray- limestone concretion\ Shale, medium gray .... inlowerpart...... Shale, dark gray to black, highly Shale, black; hard, laminated; calcareous, soft, fossili ferous; contains conodonts .... contains Aciculopecten, iVuct~- Clay, dark gray, calcareous, soft, lana ...... fossiliferous; contains produc- Limestone, contains numerous tids ...... thin-shelled pelecypods ... Womac Coal Member, bright Coal, bright, irregular discontinu- bands, dull on bony laminated ous band ...... planes,thin-bedded .... Clay, brownish gray, noncalcare- Underclay, noncalcareous ... ous, joints filled with secondary Underclay, greenish gray, smail calcite ...... calcareous concretions near Clay, dark gray, calcareous . . base ...... Clay, light gray streaked with Underclay, bluish to greenish brown grading down to medium gray, calcareous, starchy frac- gray; contains small, rounded ture; varies from nongritty to or uneven limestone nodules; sandy; contains calcareous nod- gradesinto ...... ules up to % inch in diameter Clay, light greenish gray, calcare- and very small crystals of ous, contains nodules up to 2 marcasite(?) ...... inches in diameter .... Shale, bluish or greenish gray, cal- Shale, greenish gray, calcareous, careous, slightly silty, thin- poorly laminated above, be- bedded, platy; contains calcar- coming well and thinly bedded eousconcretlons ..... below, with limestone concre- Sandstone and sandy shales, blu- tions up to 6 or 8 inches in max- ish gray, interbedded, micace- imum diameter ..... ous, highly calcareous (top 2 Shale, greenish gray, calcareous, inches especially calcareous), sandy, almost a sandstone or ripple-marked, thin- to med- siltstone ...... ium-bedded ...... Macoupin Limestone Member Shale, light greenish grap, some- Limestone, reddish, dense, nod- what micaceous, thin-bedded; ular, poorly bedded, fossilifer- locally includes thin beds of OUS ...... siltstone, sandstone, and lime- Shale, light bluish gray, calcare- stone ...... ous, well bedded; contains Burroughs Limestone Member, flattened, oval, greenish gray hluish gray, sandy, crystalline, limestone concretions up to irregularly bedded, very fossil- 1% inches thick near top . iferous, with occasional pebbles Shale, greenish gray, calcare- oflimestone material ... ous. micaceous. with lens- Sandstone, noncalcareous, fine- like masses of calcareous grained, interlaminated with sandstone, slightl?~.fossilifer- greenishshale ...... - ...... ous and contalnlng trad markings ...... Total 4h 10% Iimestone, bluish gray where fresh, weathers to streaky, rusty brown; densely crystal- line, fossiliferous, nodular . (Overlap 1)etween geologic aectionk 7A xnd 7Rj Shale, greenish grap, calcare- ous, micaceous, with scatter- Geologic section 7B ed discoidal ironstone con- Shale, light greenish gray, slight- cretions disvlacing the shale ly gritty, noncalcareous, mica- laminae by their growth; ceous, platy, fossiliferoui hori- jpints. filled with calcite and zon about 10 inches ahove 1)n.c. 1 Irmonite ...... Burroughs 1,imestone member, Limestone, greenish, lxownish, purpliqh brown, coarsely cryc- and dark gray, crinoidal, talline, crinoidal, cross-bedded; granular, abundantly fossil- interlaminated with greeni\h iferous, with hTeosp?i,'L~l- shales, somewhat arenaceoai, come?-atus ...... occasionally marked by car- Shale, greenish gray, lower part bonaceous traces; carries large dark gray, calcareous, fossil- productid brachiopods; slump i ferous, with fi attened oval down in large irregular blocks . 1 nodules of crystalline lime- Sandstone, grny, lenticular, mud- stone ...... cracked and ride-marked. in- TYPE AND REFERENCE SECTIONS 69

Thickness: (ft) (in) Thickness: (ft) (in) terlaminated with thin lenses Shale, light gray; silty; shows of greenish gray, noncalcare- s~hcroidalweathering ...11 ous shales; at its base locally ~hde,light olive or- brownish occurs what seems to be a de- gray, soft, clayey; thickness composed limestone with many varies from 6 to 7 feet ... 6 fossils, chiefly gastropods . . 10 Shale, black, hard, not fissile, Shale, olive-gray, slightly calca- s!ightly canneloid . . reous, evenly bedded. ... 7 Chapel (NO. 8) Coal ~emder,' Shale, blue-gray, better bedded fairly soft and shah .... than above; contains medium ~nderkla~,light to medium gray, purplish gray concretions, py- not bedded: some ironstone or rite concretions, and .a few freshwater hmestone nodules . 2 black, carbonaceous Impres- sions, possibly plant remain\ Trivoli Sandstone Member (?); marked near the base by Sandstone, shaly, light brown- crescent-shaped fractures . . 8 8 ishgray ...... 1 Sandstone, more massive than Carlinville Limestone Member preceding, absent down- Limestone, very nodular, fossil- stream (lenticular?); thick- i ferous ...... 1% ness varies from 1% to 3 feet . 2 Shale, medium gray .... % Shale or clay, dark greenish Limestone ...... 1 6 gray ...... Shale, greenish gray, with nod- Total 21 10 ules of freshwater limestone . 4 Shale, light bluish gray, silty, with some small ironstone (Probable overlap between geologic sections 7R and concretions...... 10 7C) Siltstone band, brownish gray, hard ...... Geologic section 7C Siltstone, shaly, and sandy Carlinville Limes tone member shale, light gray with red- Limestone, light brownish gray, dish cast, minutely cross- dense to subcrystalline, abun- bedded, with thin, discon- dantly fossiliferous (Osagia, tinuous lenses of fine sand- Neospirifer, Composita, etc.); stone; some shale and sandy loose blocks very nearly in shale strongly cross-laminated 15 place ...... 2 Sandstone, olive-gray, fine- Shale, light gray, calcareous, grained, medium-bedded . . 5 with ironstone or ferruginous Shale, light gray, silty, with car- limestone nodules .... 2 bonaceous mat ter, becomes Limestone. brownish gray, clayey downward ....22 platy, aigi!laceous, foss'%fekl ous, in calcareous shale . . Scottville Limestone Member Limestone, dark gray, weather- Limestone, dark bluish gray, ing light gray, dense, deeply dense, massive, well jointed; fissured by solution along joints widened by solution . 1 Joints ...... Limestone or calcareous iron- Shale, black to dark gray, soft stone, brownish gray, fossil- (not fissile), with worm tubes i ferous ...... 4 and fossils (Neospirycr, Com- Limestone, medium bluish gray, positn, etc.) ..... dense, fossiliferous; forms Limestone, medium brownish pavement in creek for 300 gray, rather dense, slightly feet...... 2 2 fossiliferous, massive, poorly Shale, dark gray, calcareous, bedded; forms falls in stream soft, slightly fossiliferous . . 1 Shale, dark brownish gray, car- Total 103 4 bonaceous, soft; indistinct plant traces ...... Shale, light gray, slightly silty, (Overlap of part of Trivoli Sandstone Member be- with well ~reservedCdamites tween geologic sections 7C and 7D) and pther 'stem and leaf com- presslons ...... Geologic section 7D Shale, light gray, silty, becoming more sandy downward, slightly Trivoli Sandstone Member, ripple-marked, without plant brownish gray, fairly coarse- traces ...... grained, soft, friable, cross- Siltstone or sandstone, light gray, bedded, thin to massive in 3- to massive, lenticular unlts In a 6-inch beds; massive beds are generally shaiy series; thickness lenticular; large mica flakes and varies from 4 to 5 feet; possible carbonaceous flakes on bedding small unconformity at base . . planes ...... 70 ILLIATOIS STATE GEOLOGICAL SURVEY R. 1. 214

Thickness: Thickness: (in) Scottville Limestone Member, lar in upper part, noncalcare- brownish gray; weathers dull ous but contains embedded gray; hard, massive, somewhat gray calcareous nodules % to rectangularly jointed, fossilifer- j.i inch in diameter; thickness ous (crinoids, Composita); thick- varies from 3 to 4 feet . . . 6 ness varies from 2%. - to 3 feet . Shale, olive-gray, nongritty, even- Shale, bluish gray, thin-bedded, ly bedded up to >i-inch thick . 9 fairly hard, noncalcareous, fos- Clay, shaly? reddish brown, slick- sili ferous is tem impressions, ensided ...... 1 Derbyia, Aviculopectzn) . . . Clay, dark gray (coal horizon) . 96 Athensville Coal Member, lenti- Clay, light gray mottled with dark cular ...... gray, soft, slickensided, non- Clay, greenish gray, nonbedded, calcareous, with carbonaceous noncalcareous., nonmttv", . . root remalns ...... 10% Shale, greenish gray, poorly bed- Clay, dark gray, interlaminated ded, noncalcareous, nongritty ; with light gray clay . . . . 2 eradesinto ...... Clay, dark greenish gray, non- SaGdstone, light bluish gray, calcareou~,slickensided . . . 4 shaly at top, poorly bedded be- Clay, light greenish gray, non- low. noncalcareous . . . . calcareous, slickensided . . . 5 ~andsione,brownish gray, hard, C 1 a y, olive-gray, calcareous, slabby, massive, spotted with blocky, harder than above . . brown noncalcareous knots . . Piasa Limestone Member Shale, pale bluish gray, evenly Limestone, gray; weathers yel- bedded, finely micaceous, lowish brown, fine-grained; slightly sandy becoming more knobby upper surface; some- sandy in lower 2 feet; thickness what nodular structure but varies from 6 to 8 feet massive in beds 8 to 10 inches . . . thick; no fossils noted in up- Sandstone, bluish gray, hard, per beds...... 6 slabby, very calcnreous, non- Shale, gray, calcareous . . . 6 micaceous; contains some Limestone, olive-gray, fine- greenish gray shale pebbles grained, hard, massive, very spotted with brown; thickness fossi 11ferous (Fusulina, Corn- varies from 2 to 3 feet . . . posita, crinoids, etc.) . . . Shale, blue-gray to olive-gray, Covered interval, very poor ex- nonsandy, evenly bedded, posures showing red shale, a somewhat massive, conchoidal thin smut band (horizon Dan- fracture; %-inch smut streak ville (No. 7) cod), and a blu- 6 feet from top . . . . . ish gray, fine-grained, finely Shale, olive-gray, rusty on frac- micaceous sandstone . . . ture surfaces, thinner bedded than above, fossiliferous (Der- Total 79 3& hjl ia) ...... Shale, bluish gray, blocky, con- choidal fracture, slickensided . Geologic section 8.-Compiled from expos- Shjtle, black, hard, fissile; becomes mcreas~nglyfossiliferous down- ures at the following localities: ward (Marginifera, Olrhicu- Geologic section 8A (from field notes of M. E. 0strom)- loidetz, Liuna, Auiculopecten, Nokomis Stone Company quarry, NEX NEX NEX gastropods, conodonts); some sec. 3, T. 10 N., R. 2 W., Nokomis quadrangle, Mont- lenses of black fossiliferous gomery County limestone present . . . . Shale, brownish gray, soft, poorly Geologic section 8B-exposures along south bank of bedded, noncalcareous . . . stream, SEX NEX sec. 28, T. 12 N., R. 1 W., Pana quadrangle, Christian County. Rock Branch Coal Member Coal ...... Geologic section 8C (modified from Gluskoter, 1958, Clay, dark bluish gray, some- p. 37-39)-east bank of the East Fork Shoal Creek, whatshaly...... NEX NWX SEX sec. 7, T. 8 N., R. 2 W., Hillsboro Coal ...... quadrangle, Montgomery County. Clay, gray to dark gray, rusty on Geologic secrion 80(modified from Simon, 1946, p. 28) joint surfaces, very rusty at --along Flat Creek in east central part of sec. 24, T. base ...... 6 N., R. 5 W., New Douglas quadrangle, Bond County. Clay, gray, calcareous, with small Geol'ogic section 8E (modified from Simon, 1946, p. 30) calcareous nodules . . . . -along Dry Fork, cen. S% sec. 7, T. 6 N., R. 4 W., Covered interval . . . . . New Douglas quadrangle, Bond County. Sandstone, olive-gray, micaceous, Geologic section 8F (modified from Simon, 1946, p. 30) fine-grained, slabby, poorly -along north-flowing tributary of Dry Fork a!ong bedded; massive beds up to 5 east edge of secs. 6 and 7, T. 6 N., R. 4 W., New inches thick; somewhat nodu- Douglas quadrangle, Bond County. TYPE AND REFERENCE SECTIONS 7 1

Geologic section 8G (modified from Simon, 1946, p. 32) Geologic section 8C -SWg NWX sec. 29, T. 7 N.? R. 4 W., Mt. Olive Tkne: (t (in) quadrangle, Bond County. Shale, gray, weathers brown to Type section of the Bond Formation. Geologic tan; clayey in part, calcareous . 1 6 section 8B includes type outcrop of the Millersville Shale, light gray, weathers brown; Limestone Member; geologic section 8C includes type genera!ly fine-grained but silty outcrops of the Coffeen Limestone and Witt Coal in part; brown staining is more Members; geologic section 8D indudes type outcrop common in silty portions; fine- of Flat Creek Coal Member; .geologic section 8E in- ly carbonaceous, micaceous, cal- cludes type outcrop of Bun~eLimestone Member; careous, no fossils observed; geologic section 8F includes type outcrop of Sorento gradesinto ...... 1 9 Limes tone Member. Shale, gray, coarse, silty, very calcareous, much iron staining, Geologic section 8A fossiliferous, crinoids apparent; Thickness: Vt) (in) contains occasional round con- Pennsyhaninn Systern cretionary masses about 1 inch in diameter and up to 3 inches McLeansboro Group long; grades into . Bond Formation . . . . Millersville 1,imestone Member Coffeen Limestone Member Limestone, light brown, dense, Limestone, gray, much iron hard, in beds ranging from staining in part, very dry, 1 to 10 inches thick, fossilifer- argillaceous, fossiliferous (cri- ous ...... 6 noids, brachiopods, bryozo- Shale. light greenish gray, mod- ans) ...... 6 erately well bedded, with ar- Shale, gray, weathering brown, gillaceous limestone nodules, calcareous, fossili ferous; be- very fosiliferous . . . . 10 comes less silty downward . 2 Limestone, light brown, dense, Limestone, gray to dark gray, hard, in beds ranging from 1 weathers brown; dense, fine- to 10 inches thick, fossilifer- grained; contains occasional ous...... 5 shnly streaks, very fossilifer- Limestone, mottled light and ous (crinoids, brachiopods, medium gray, fine-grained bryozoans) ...... 7-12 with scattered medium- and coarse-grained fossil frag- ments; calcite nests; in beds (Note: Locally, within the outcrop, the lower lime- ranging from 6 to 18 inches stone bench appears to thicken to about 17 inches and thick ...... 17 the upper bench becomes a very argillaceous limestone Limestone, gray, fine-grained, about 11 inches thick.) argillaceous . . . . . 1 6 Siltstone, light gray . . . . - Shale, gray, soft, iron-stained, calcareous, fossi!iferous . . 1 Total 30 4 Shale, gray, suft, with much car- bonaceous and coaly plant de- bris; occnsional coaly streaks (Probable overlap between geologic sections 8A and up to %-inch thick; grades Into 6 8B) Shale, grav, fairly. well to well laminated; conmns many car- Geologic section 8B bonaceous fragments concen- McLeansboro Group trated on beddi~gplanes; irpn- Bond Formation staining on partings mcreasr ng Millersville Limestone Member in intensity downward; less Clay, grav, plastic, with lime- carbonaceous material in lower s tone nodules and fragments part:gradesinto. . . . . 4 loosely embedded in clay . . 2 Shale, medium dark gray, fine- Limestone, white, very much grained, thinly laminated, weathered, "algal," very fos- earthy in part; contains plant siliferous,fusulinids . . . 2 fragments; much iron-oxide Siltstone, with sandy interbeds . 7f staining along partings; grades Siltstone, increasingly sandy, with into ...... 3 thin beds of sandstone inter- Shale, gray to dark gray, thinly bedded with shale near base . . 5f bedded (but not as thin!y as above); occasional carbona- Total 16f ceous partings . . . . . 4 Shale, gray, a few thin coaly streaks ...... (There is an estimated 60 feet of strata between geologic sections 8B and 8C. Shale, sandy shale, and Witt Coal Member sandstone are included in this interval [see geologic Coal ...... 1 section 91. Only scattered outcrops are known that Shale, black, very thinly bed- include parts of this interval.) ded, coaly ...... ILLINOiS STATE GEOLOGICAL SURVEY 13. I. 214

Thickness: (ft) (in) Thickness: (ft) {i~) Underclay, medium gray, has Clay, gray, weathering yellowish mottled appearance owing to brown; carbonaceous; some slip abundant black carbonaceous fractures, noncalcareous . . 8 material and iron-oxide stain- Clay, similar to above, calcareous, ing; contains carbonaceous root contains sma!l calcareous nod- remains; blocky, poor!y bedded ules and limy concretions up to Clay, light greenish gray, uncon- 3 inches across ..... 2 solidated, very poorly lami- Shale, light gray, hard, compact, nated, cal~areou~;becomes silty, noncalcareous .... 1 4 more calcareous downward; Shale, medium gray, well bedded, abupdant small sideritic con- slightly ca!careous at top, be- cretions up to M-inch dia- coming more calcareous toward meter; concretions more abun- base, occasional calcareous con- dantatbase...... 1 3 cretion ...... 4 Clay, medium to light gray, poor- Bunje Limestone Member, ,$ive- ly laminated, slightly calcare- gray, fine "mud texture, uni- ous, iron-oxide staining along form; cone-in-cone structure bedding and partings; contains throughout; app are n t mud small sideritic concretions up cracks where surface is well ex- to %-inch diameter .... posed ...... 0-2 Clay, medium to light gray, slightly calcareous, poorly lami- Total 12 8f nated; contains very small spherical concretions [less than 1/16-inch diameter) and iron- oxide staining along bedding (Overlap between geologic sections 8D and 8E) andpartings ...... 6 Geologic section 8E Total 1 - n. Bunje Limes tone Member, bluish gray, weathering reddish brown, very fossiliferous; large (There is an estimated 40 feet of strata between pelecypod fauna in beds up to geologic sections 8C and 8D. Shale, sandy shale, 3 inches thick; one prominent and sandstone are inc!uded in this interval [see geologic clap parting; top of bed locally section 91. Only scattered outcrops are known that shows cone-in-cone structure . 8-1 8 include parts of this interval.) Sandstone, bluish gray, shaly, calcareous ...... 1 4 Geologic section 8D Sandstone, bluish gray, calcare- ous, hard, massive; weathers Limestone, weathers reddish shaly, changes laterally to soft, brown; fossili ferous, local oc- shalv sandstone ..... 1 3 currence ...... ~hale,'bluishgray, sandy, thinly Shale,. yellowish gray, calcareous, and evenly bedded .... h fossil^ ferous, somewhat car- Sandstone, tan to light gray, mi- bonaceous ...... caceous, massively bedded in Shale, dark gray to black, non- benches up to 8 inches thick; calcareous, carbonaceous; some cross-bedded; wavy concretion- yellowish clay partings ... ary beds contain irregularly shaped flattened sandstone con- Shale, dark gray to black, flaky, cretions; massive beds ripple- fine, thin-bedded, noncalcare- marked; becomes shaly in lower OUS ...... part ...... 15f Shale, black, hard, fissile; mini Shale, bluish gray, smooth, thinly mum thickness where under- and evenly bedded, finely mi- lain by limestone clod, maxi- caceous, noncalcareous 20f mum where underlain by coal . ... Limestone, bluish gray, clod, rela- Total 39 3% tively soft, very fossiliferous, dark gray to black fossiliferous shale parting 0 to 8 inches thick in middle; 1. to 2 inches at top (Geologic sections 8E and 8F nearly continuous) of clod hard; quite variable in single exposure, local :n occur- Geologic section 8'F rence ...... 0-2 Flat Creek Coal Member ... 8-1 2 Sorento Limestone Member Underclay, light gray, noncalcar- Limestone, dark bluish gray, eous; some carbonaceous ma- weathering reddish brown; terial, but not typical carbona argillaceous, fi n e-g r a i n e d, ceou~root remains .... 2 3 massive, fossiliferous; upper TYPE AND REFERENCE SECTIONS 73

Thickness: (in) Thickness: (ft) (in) surface has large fucoid mark- Shale, black, thin-bedded, with ings up to % inch in diameter 3-4 coalified plant compressions . 10 Shale, medium to dark gray, New Haven Coal Member, quite fossiliferous ..... 1-3 variable in thickness ... 1-15% Limestone, bluish gray, weath- Underclay, gray to greenish gray, ering light gray; argillaceous, noncalcareous ..... 2 fine .to medium crystalline, Clay, gray to greenish gray, non- masswe; weathers slabby, calcareous, weathering yellow- fossiliferous (bryozoans, spiri- ish brown ...... 2 fer, Composita, gastropods, Shale, gray, thin-bedded, noncal- crinoids, trilobites, and many careous, finely micaceous, large flat remains of pelecy- weatheringbrown .... 6+ podAviculopinna) ... 6-16 ..- -- Shale, dark gray to black, cal- Total 16=t careous, thin-bedded, fossilifer- ous, absent where coal is found 0-4 Coal, usually much weathered, absentlocally ..... %-I % Geologic section 9.-From log of Peabody Underclay, greenish gray, non- Coal Con~panydiamond drill hole 59, NW% calcareous, hard, slip-fractured 2 NE% NE% N?T7% see. 33, T. 11 N., R. 1 E., Clay, gray, blocky, noncalcareous 3 Pana quadrangle, Christian County. Surface Clay, gray, block?; contains cal- elevation, 671.78 feet. Twenty-eight selected careous concretions .... 5 samples of the Bond Formation are on file at Shale, gray, weathering reddish the Geological Survey, Urbana, Core 2409. brown; calcareous, fine-grained, poorly bedded ..... 8 Shale, bluish gray, thin-bedded, Reference section of the Bond Formation. calcareous; contains reddish brown limy concretions and Thi~.km.s.~:(ft) (in; fairly persistent horizontal con- centrations of these concretions Pennsyluanian System Shale, bluish gray, thin-bedded, McLeans boro Group calcareous, fossiliferous ... 6 Mattoon Formation Limestone, gray, coarsely crystal- (depth 97 feet) line, very fossiliferous, massive, usually quite argillaceous . . 4-7 Clay, probable core loss ...12 9 Shale, medium gray, thin-bedded, calcareous, fossiliferous ... 2 Shale, medium gray, noncalcare- Bond Formation ous, thin-bedded, silty ... 2 Mil!ersville Limestone Member Shale, medium gray, silty, thin- Limestone, nodular, white, ar- bedded, finely micaceous, cal- gillaceous ...... 5 3 careous with some calcareous limestone, nodular, white, concretions ...... 10 pure; no partings except in bottom 6 inches; vuggy . . 16 5 Total 23 3f Shale,--+rk gray, hard, very fossiliterous ..... Limestone and shale interbed- ed, shale dark gray like above (Geologic sections 8F and 8G nearly continuous) Limestone, gray, massive, nod- ular, fossiliferous, stylolitic . Limestone. gray, massive, nod- Geologic section 86 ular ...... Limestone, as above, in frag- Shoal Creek Limestone Member, ments, gray, hard; dense gray to bluish gray, somewhat nodules ...... darker toward base, fine, com- Limestone, gray, dense, mas- pact, hard, massive, fossilifer- sive, similar to above ... ous ...... 6-13f Limestone, gray, dense, with a few shaly partings that are irregular; uneven contact at ?vlodesto Formation base of limestone .... Shale, dark gray, thin-bedded, Shale, dark gray, very silty, fos- smooth, fine, noncalcareous; siliferous, calcareous; grade5 contains Aviculopecten ... 5% into ...... Shale,.black, fissile; contains con- Sandstone, light gray, fine, with cretlons; fossiliferous (Avicu- thin, light gray, silty laminae; lopecten, conodonts) .... 1 8 gradesinto ...... Sha!e, light gray grading down Shale, gray, fairly soft, with to medium gray, thin-bedded, several dark gray partings; noncalcareous .....2-4 calcareous ...... 7 4 ILLINOIS STATE GEOLOGICAL SURVEY R. I. 214

Thickness: (ft) (in) Thickness: (in) Siltstone, gray, with finely inter- Shale, s!ightly darker than above, laminated carbonaceous shale; pyritic nodules; better lami- carbonaceous shale about 10 nated than above; micaceous . 5 percent; calcareous .... 7 Shale, dark gray as above; and Shale, dark gray, calcareous . . ?4 siltstone, !ight gray, fairly Siltstone or fine sandstone inter- evenlyinterbedded .... laminated with shale; more uni- Siltstone, gray, shaly, micaceous; form in upper 2 inches, calcare- carbonaceous fragments; mas- ous below ...... 7% sive...... 9 Siltstone or fine sandstone as Siltstone, as above, broken pieces 7 above, calcareous .... 1 10 Siltstone, as above, unbroken, very micaceous; carbonaceous (depth 150 feet) from 22 to 25 inches from top . 6 Siltstone or fine sandstone, gray, Shale, light gray, massive, mica- calcareous with thin, occasional ceous; carbonaceous fragments 11 micaceous and carbonaceous laminae, generally uniform, cal- (depth 180 feet) careous ...... Shale, light gray, coarse with thin Siltstone or sandstone, as above laminae and lenses of white (broken pieces) ..... siltstone giving shale a some- Shale, gray to dark gray, mi- what "birdseye" appearance . 2 8% caceous, medium-grained; car- Siltstone, light gray, finely inter- bonaceous plant fragments; laminated with micaceous and fairly well laminated with light carbonaceous partings ... 1 gray siltstone laminae and Shale, gray, micaceous, medium- layers ...... grained, with two bands of Sandstone, light gray, fine, with siltstone from 6% to 7% inches thin, dark gray shaly laminae . and from 9% to 10 inches from Shale, gray, with a few thin silt- top ...... 1 8 stone laminae; micaceous . . Siltstone, gray, becoming shaly Siltstone or fine sandstone, light in bottom 6 inches .... 2 2 gray; thin laminae of carbona- Shale, medium gray, fairly well ceous shale similar to above: laminated; thin laminae and very micaceous ..... lenses of light gray siltstone . 2% (depth 160 feet) (depth 190 feet) Shale, gray, micaceous and car- Siltstone, gray, with carbonaceous bonaceous partings, with light plant fragments; massive . . 8% gray siltstone laminae decreas- Shale, gray, micaceous, fairly well ing in amount downward; bot- bedded; some black shale in tom two inches siltstone . . thin regular and irregular Shale, gray, rcassive; carbonace- bands; thin lenses and bands of ous plant ~mpressions; some- lightgraysiltstone .... 3 4 what silty, pyritic .... Siltstone, gray, massive, with car- Siltstone, light gray, somewhat bonaceous plant debris ... 4 carbonaceous; shale, gray, in- Shale, gray, micaceous, with 5 terbedded and interlaminated . percent thin light gray siltstone Shale, gray, micaceous (broken lammae ...... 7% pieces) ...... Shale, light gray, massive, mica- Shale, gray, similar to above, in- ceoas, broken fragments . . 6 terbedded with light gray si!t- Shale, gray, massive, coarse; simi- stone; two benches of shale with lar to siltstone above but finer 8 siltstone between .... Shale, medium gray, fairly well Shale, gray, with thin laminae of laminated, with thin discon- light gray siltstone; micaceous; tinuous white siltstone laminae; fairly uniform; broken pieces . some beds fairly silty ... 3 10 Shale, gray to light gray, very micaceous, with carbonaceous (depth 200 feet) fragments; laminae of light Shale, steel gray, micaceous, well gray siltstone and black car- laminated, a few thin siltstone bonaceous shale ..... parti~gs ...... 1 Siltstone, gray, micaceous, with (depth 170 feet) some light gray irregular silt- Siltstone, gray, massive ... 4 stonelaminae ..... 1 8 Shale, medium dark gray with Shale, light gray, with a few light irregular lenses of light gray gray siltstone lenses .... 2 siltstone, fairly well bedded; Siltstone, light gray, carbonized tends to break into chips . . 1 6 plantfragments ..... 2 8 Shale, , gray, silty, micaceous, Shale, light gray, banded with masslve; carbonaceous plant thin white siltstone partings; material; grades into ... 1 1 tends to split along bands . . 2 6 TYPE AND REFERENCE SECTIONS

Thickness: tft) (in) Thickness: (ft) (in) Siltstone, light gray .... 1 8 Clay, mottled greenish gray and Shale, light gray, with thin light dark brown, with vertical siltstonelenses ..... 4 stringers or cracks; an occasion- a1 limestone nodule .... 1 9 (depth 210 feet) Clay, greenish gray and brown Siltstone, light gray, massive, mi- with bluish green limestone caceous ...... nodules that are argillaceous, Shale, light gray, fairly well lami- nonfossiliferous and up to 4 nated ...... inchesacross ...... 10 Siltstone,lightgray. .... Clay, mottled dark brown and Shale, medium dark gray, micace- greenish gray; grades into . . 4 ous, fairly well bedded ... (depth 250 feetj Siltstone, light gray and dark Clay, same as above; grades into . 3 gray finely mottled; grades Into Clay, silty, greenish gray; con- Shale, light steel gray, masslve . tains a few light gray silty Gap-coreloss ...... streaks ...... 2 4 Siltstone, light gray, hard, cal- Clap, dark gray; streaked and yel- careous ...... low mottled ...... 2 6 Shale, gray, fairly well bedded, Clay, dark gray, yellow mottled; uniform, finely micaceous, be- relatively soft, very friable; coming darker and less silty like above but slightly darker . 2 1 toward the bottom .... Shale,. gray to dark gray, well (depth 260 feet) laminated, relatively soft . . Shale, dark gray; pyritic trails; Sha!e, medium dark gray, well relatively soft; fair lamination 1 laminated, pyritized in part Shale, dark gray to black, with with an occasional siderite con- siderite bands and lenses up to cretion; fossiliferous (s m a 1 l 1 inch thick; very friable; pyri- gastropods) ...... tizedtrails ...... 3 4 Shale, as above, broken fragments Shale, similar to above; broken Shale, gray, similar to above, with pieces; fossiliferous (Aoiculo- siderite nodules, pyrite trails, pecten) ...... 1 4 and a few fossils ..... Shale, dark gray, similar to above; Coffeen Limestone Member (?) pyri tized trails and siderite Space partly filled with lime- bands...... 2 7 stone pebbles, greenish gray, Shale, medium gray, fossiliferous dense, lithographic, some- (gastropods and pelecppods) ; what like freshwater lime- poorly laminated; somewhat s tone ...... pyritic; grades into .... 5 Shale, dark gray, soft, fossils Shale, gray, massive, less fossilif- (mainly Aniculopecten; one erous than above (gastropods, possibleseed) ..... pelecypods); pyritized trails . 1 4 Lime~tonenodule. dark gray .

Shale, dark gray to black, Lssilif- \ L erous (Aviculopecten. produc- Shale, dark gray; pyritized trails; tids, ~ih~ula,e&.) ;ca;bokaceous relatively soft, fairly well lami- Witt Coal Member, normally nated, slightly fossiliferous . . I 7 banded; two thin clay bands in Sha!e, same as above, broken upper 2 inches ..... , - ~ieces...... 8 Underclay, gray, with carbona- ~hjle.dark gray to black, rather ceous root remalns (broken poorly laminated, pyritic, fos- fragments) ...... 2 siliferous(pelecypods) ... 2 6 Gap-coreloss ...... 9% Limestone, greenish gray, mas- slve, dense, fossiliferous (in- (depth 230 feet) cluding mic~~fussils).... 4 Gap-about one foot of clay, gray, Shale, dark gray to black, cal- with many small limestone careous, very fossi!iferotrs, car- pebbles recovered; a few pieces bonaceous and argillaceous; of limestone in core box just contxns megaspores ... 1 4 Flat Creek Coal Member, normal- above the clay .....10 ly banded ...... 1 % (depth 240 feetj Underclay, with carbonaceous root remains; slip-fractured; Gap-core Ioss ...... 1 9 gradesinto ...... 2% Clay, greenish gray, soft, slip- Clay, greenish gray, slip-fractur- fractured; limestone nodules, ed; calcareous below first 3 greenish gray, dense, sideritic inches...... 1 2 in part ...... 2 1 Gap-coreloss ...... 1 2 Clay, mottled green and yellow- ish brown, with gray limestone (depth 280 feet) nodules about 10 percent . . 2 2 Gap-coreloss ...... 14 76 ILLINOIS STATE GEOLOGICAL SURVEY R. I. 214

Thicfiness: (ft) (in> Thickness: (ft) (in). . Bunje Limestone Member Shale, medium light gray, finely Limestone, gray, and shale, mlcaceous, with thin white green; upper part with cal- siltstone streaks playing out careous, fine, light gray sand- toward base; grading into . . 9 stone; lower part all fragmen- Shale, medium gray, well lami- tal, making exact position nated, relatively hard, tends to questionable ..... 1 4 break in chips; pyritized trails Shale, gray and green, inter- in bottom 3 inches .... I1 laminated with light gray Shale, dark gray, calcareous and siltstone; faint ripple mark fossiliferous; fossils poorly pre- structure ...... I 1% served ...... 1 Limestone, brownish gray; im- Shale, grap, poorly laminated, pure, hard, fossiliferous . . 2% slightlysiity ...... 2 Shale, dark gray, ripple-marked, Shale, dark gray, irregularly in- with fine, white siltstone; con- terlaminated with light gray tains siderite concretions; cal- siltstone ...... 7 careous in upper part ... 3 Shale, medium light gray, mas- Siltstone, light gray or fine sand- sive, irregularly interlaminated stone interbedded and inter- with small amount of light gray laminated with shale, dark siltstnne ...... 1 4 gray, somewhat cross-bedded Shale, gray to dark gray, fairly and ripple-marked; 75 percent well laminated, with thin lam- silts tone ...... inae of white siltstone; more regular than above, giving shale (depth 300 feet) more banded appearance . . 2 6 Siltstone, light gray, with thin carbonaceous shale laminae; (depth 340 feet) somewhat cross-bedded ... 10 Shale, as above, slightly ripple- Siltstone, gray, with somz light marked ...... 3 3 gray siltstone giving marbeloid Gap-core loss (probably same as structure ...... 2 5 shale above) ...... 1 Siltstone, as above in two broken Shale, gray, fairly hard, brittle, pleces ...... 3 with a few thin, light gray silt- Siltstone, as above, massive, uni- stone layers; sideritic and cal- form ...... 3 6 careous in some bands ... 4 Siltstone, as above, broken pieces 1 Shale, similar to above, with more Siltstone, as above, mxssive . . I 11 frequent sideritic and calcare- ous bands in upper 9 inches . . 1 8 (depth 310 feet) Siltstone, as above, with occasion- (depth 350 feet) al layers of light gray to white Shale, steel gray, well bedded, be- siltstone interbedded with gray coming more friable toward siltstone in beds 3 to 4 inches base ...... 4 thick ...... 10 Sorento Limestone Member Shale, medium gray, fairly soft, (depth 320 feet' very fossiliferous (layer 2 to Siltstone, as above ..... 3 3 inches from top especially Gap-coreloss 1 6 fossiliferous) ...... Shale, gray to dark grap, very Siltstone, as above, broken pieces 5 7 fossiliferous, almost lime- Siltstone, as above ..... 1 stone, relatively hard ... Shale, gray to dark gray with thin Shale, gray, calcareous, fossilif- white siltstone laminae about erous ...... 10 percent; regular interlnmina- Shale, gray, very calcareous, tions ...... 8 very fossiliferous, almost a Siltstone, gray, with dark gray limestone ...... streaks, fine-grained, breaks Shde, gray, very well and finely easily across bedding at streaks 2 10 laminated; breaks into small (depth 330 feet) chips ...... Shale, black, poorly laminated, Sil tstone, gray, fi ne-grained, well brittle and fossiliferous ... laminated, micaceous, carbona- Coal, normally banded ... ceous, fairly hard .... 1 7 Underclay, with carbonaceous Shale, medium gray, irregularly root remains; friable, slip-frac- interlaminated with light gray tured ...... siltstone; 1-inch fossiliferous Clay, greenish gray; occasional siderite layer or lens at top . . 11 limestone pebble; much core Siltstone, gray, fine-grained, mlssing ...... somewhat coarser and more car- bonaceous in upper 5 inches . 1 (depth 360 feet) TYPE AND REFERENCE SECTIQATS 77

Thickness: Cft) (in) Thickness: (ft) (in) Clay, greenish gray, grading into Modes to Formation poorly bedded shale with fre- quent irregular limestone nod- Shale, dark gray in upper 3 inches, ules that become less frequent calcareous. fossilifero~is,~oorlv toward base ...... 3 2 bedded; bieaks into smdl a;- Shale, green and grayish green, gular fragments; grades into . 10% somewhat mottled, smooth; oc- Shale, black, well bedded, becom- casional limestone nodule . . 3 10 ing fissile in the bottom 10 Sideriteband ...... 1 inches; some pyritic trails one Shale, green with some greenish foot above the bottom ... 2 I gray mottling, smooth, fairly well laminated ..... 9% (depth 400 feet) (depth 370 feet) Total 2 11% Shale, as above ...... 2% Shale, greenish gray mottled with gray, fossili ferous (0s tracodes) 2% Geologic section 10,The following outcrop Shale, greenish gray, very cal- sections contain most of the named members careous, fossiliferous, almost a of the Mattoon Formation. Intervals between limestone,sideritic .... 3 Shale, greenish gray to gray, fos- sections are uncertain. siliferous, becoming less fossil- Geologic section 10A.-North-facing cut /ferous toward base; grading mto ...... 3 bank of West Crooked Creek %-mile west of Shale, gray to dark gray, fairly bridge in NE% NEIL sec. 16, T. 7 N., R. 10 E., wel! laminated, uniform ... 4 Greenup quadrangle, Jasper County. Shale, dark gray, calcareous, very fossiliferous (small forms); an Type outcrop of the Reisner Limestone Member. infrequent limestone nodule . 1 7 Thickness: (ft) (in) Shale, gray, calcareous, less fos- siliferous than above. ... 3 Penn~ylvaninnSystem Shale, dark gray, very calcareous McLeansboro Group and fossiliferous, almost a lime- Mattoon Formation stone ...... 5 Shale, light gray to medium gray, Gap-fragments of gray fossilifer- weathered, soft, much iron- ous shale and limestone nodules stained ...... 1 8 recovered ...... 3 2 Shale, medium dark graJT, thinly Shoal Creek Limestone Member laminated, smooth; some iron Limestone, upper six inches stalning ...... 1 2 dark gray, remainder light Shale, dark gray, well laminated, gray, dense, compact, fos- with iron staining on bedding siliferous; very shaly in part 2 8 nlanes; becomes darker at base; Limestone, gray, fossiliferous, irades into ...... I 6 argillaceous, hard, with a few Sha!e, black, fissile, sheety . 1 5 shalystreaks ..... 1 1 Reisner Limestone Member Limestone, gray, fossiliferous, Limestone, shaly, brown, soft, with thin irregular black weathered to clay in part; a. shale layers %-inch thick; containsgypsum-. ... 1% gradesinto...... 10 Limestone, g~ay,very argilla- Limestone, in beds 1 to 4 inches ceous. fossiliferous: contains thick, light gray and gray; an agundance of fossil frag- irregular beds of dark gray ments and small brachiopods argillaceous limestone 3.i to including Crurithyris ... 295 4 inches thick; all fossilifer- Shale, brown, much weathered, ous...... 1 5 very calcareous, fossiliferous I I4 Limestone, gray, somewhat Limestone, gray, very argilla- nodular with a few black, ceous, fossili ferous, includ- thin shdy partings; in gen- ing many hrachiopods; var- eral fairly massive ... 3 5 ies from 2 to 31%, - inches thick 3 Limes tone, gray, fossili ferous, Clay, medium gray, occasional similar to above, with shaly carbonaceous streaks, blocky, calcareous partings every 3 friable, noncalcareous; may be to 6 inches; partings are ir- anunderclay...... regular; partly nodular; Clay, medium dark gray, slightly grades into ..... 6 10 c a 1 c a r e o u s, carbonaceous, Limestone, dark gray, very ar- grades into ...... gillaceous, fi&siliferous; grad- Clay, light gray, greenish cast; inginto ...... 1% sor?e. black manganese (2) staming, silty, soft, friable, Total 286 11% noncalcareous; abrupt change at base ...... I iELIATOIS STATE GEOLOGICAL SURVEY R. I. 214

Thickness: ($) (in) Thickness: (ft) (in> Clay, gray, soft, friable, silty, Sandstone, thin-bedded, locally very calcareous . . . . . 6 massive, calcareous; sandy shale Clay, light tan, very calcareous; with hard, dense, calcareous may be weathered limestone . !d siderite nodule bands exposed Limestone, light gray, weathers down creek for nearly % mile . 7+ with slight yellowish cast in part; weathers knobby to rub- Total 18 lo+ bly; fossils not noted; this and underlying unit appear to be very variable in thickness in the area, although not so in Geologic section 10C.-Section exposed near thisexposure...... I 2 mouth of small tributary valley, along Mint Limestone, similar to above, but Creek, NE% SW% see. 31, T. 8 N., R. 9 E., more massive; tends to spall into slabs; argillaceous; no fos- Teutopolis quadrangle, Jasper County. sils observed; base conceded at creek level ...... 1 10 Type outcrop of the Gila Limestone Member. Total 12 11 Thickne~s: (ft ) (in) Penrrsj~ivanzanSystem McLeansboro Group Mattoon Formation Geologic section 10B (modified from field Shale, .light gray, some yellow notes of S. E. Ekblaw).-Traverse down Web- staining; t h i n 1 y laminated, ster Creek about the middle of the S% SEX smooth, wel! bedded, noncalca- see. 32, T. 9 N., R. 8 E., Teutopolis quadrangle, reous ...... Cumberland County. Shale, gray mottled with dark gray, smooth, well laminated; Type outcrop of the Woodbury Limestone Member. contains cdcareous sideritic lenses up to 2 inches thick and 10 inches across; shale is cal- Thickness: (ft) (in) careous and becomes gray to Penrrsylvanian System light gray in lower part; con- McLeansboro Group tains well preserved gastropods Mattoon Formation and some small peiecypods; Shale, drab to grayish drab, silty siderite nodules in float with Shale, grayish drab, fossiliferous, similar fauna probably weath- ostracodes and brachiouods . ered out of this shale . . . Shale, dark gray to black, fossil- Shale, black, smooth, well lami- iferous. ostracodes. brachio- nated, fissile in part, noncalca- pods, and some gastropods . . reous ...... Woodbury Limestone Member Coal, bright-banded, somewhat Ironstone lnyer, medium gray; weathered; no prominent part- weathers reddish and rusty ings noted; up to 5 inches thick brown; hard, fossiliferous, Clay, gray, mottled with brown containing Strapnrohs catil- where weathered, slightly car- loides, Pharkidonotus per- bonaceous, noncalcareous . . cnrinatus, Meekospira pern- Siltstone, gray, very argillaceous, cuta, Glabrocingulu m gmajeil- calcareous, friable; occasiqnal lense, Lophoph.rlliiZizlm proli- carbonaceous root remains; ferunz, Crz~rith~vrisplunocon- becomes more sandy down- oexa, iMarginifefaj crinoid ward; contains dense, round stems, and a species of nau- hmestone concretion 6 inches tiloid ...... across near the base . . . . Shale, djrk gray to bluisc gray: Siltstone, gray, dense, hard, cnl- contains a few small calcn- careous; grades laterally to ar- reous nodules; fossiliferous gillaceous sandstone that is be- {Crurithyrls); grades into . lieved to represent the "pock- Shale, black, coaly, with many marked" sandstone in the sec- gypsumcrystals . . . . . tiondescribcdbelow. . . . Coal, good, hard . . . . . Shale, gray, poorly laminated, Shale, black, very carbonaceous, silty, calcareous, relatively soft ...... hard, almost a siltstone . . . Underclay, grayish blue, sandy; Siltstone, gray, sandy, numerous some carbonaceous plant re- calcareous and sideritic nodules mains; coaly in part; becomes up to 2 inches across; base con- shaly towardbase . . . . cealed near creek level . . . TYPE AND .REFERENCE SECTIONS 79

Thickness: (ft) (in) T4icknes.c: (fi (in) (Note: Section described below in small tributary ra- overlying cone-in-cone lime- vine believed to overlap above section bv about stone is generally absent.) 3 feet.) Limestone is in Led of creek . 8 Clay, brownish gray, silty, soft, Sandstone, light gray, medium- carbonaceous, weathered (ex- to fine-grained, dense, hard, nosed below limestone a short finely micaceous, very calca- distance down stream; base reous; recrystallized calcite glis- concealed, ...... 1 6+ tens on freshly broken surfaces; forms prominent resistant ledge Total 29 that presents weathering aspect of a limestone. ... Shale, greenish gray, silty, soft, friable ...... Geologic section 10D (modified from field Sandstone, gray, medium-grain- notes of S. E. Ekblaw).-Section near foot of ed, dense, hard, micaceous, hill on State Highway 131, near center W1% more argillaceous than sand- NE% sec. 3, T. 9 N., R. 9 E., Toledo quadran- stone above: an occasional car- gle, Cumberland County. bonaceous plant fragment; weathered surfaces show con- Type outcrop of the Greenup Limestone [Member. spicuous small holes or "pock- marks" ...... Thickness: (fi) (inI Shale, gray, slightly silty, with Penns-ylvanian System occasional carbonaceous part- McLeansboro Group ings ...... Mattoon Formation hale, light gray with greenish Clay, yellowish brown, deeply cast. smooth: occasional small weathered ...... I+ sideiitic nodLles; poorly lami- Greenup Limestone Member, nated in upper part, becoming medium gray to grayish white, better laminated downward; dense to subcrystalline, argilln- contains nodules and thin, ceous, very fossiliferous, con- irregular bands of very calcare- taining fusulinids in top 10 ous sandstone up to 1-inch thick inches and gastropods, cora!s, Shale, gray, smooth, well lami- brachiopods and numerous cri- nated, rather uniform, with oc- noid fragments in the lower casional irregular calcareous part; irregularly bedded; ap- sideritic nodular masses from I pears to be nodular in places . 3+ to 6 inches across .... Shale, buff to greenish graTi, snn- Gila Timestone Member dy, thin-bedded, slightly mi- Limestone, gray, dense, fine- caceous ...... 5 grained; weathers orange- Sandstone, buff, fine-grained, cal- brown; hard; no fossils ob- careous in upper part ... 4 served except fish scales, Shale, dark gray, thinly lami- teeth, etc., which are black nated, silty, micaceour, sandy and not numerous. ... in places, with a 2-inch sand- Shale, greenish gray, thinly stone layer 3 inches from the laminated, soft, with occa- top; base concealed ....12f sional carbonaceous streak . -- Limestone, gray, dense, fine- Total 25+ grained, lithographic; no fossils observed except occa- sional fish remains; ranges up to 3 inches thick in nearby Geologic section POE (modified from Newton exposure< ...... and Weller, 1937, and field notes).-Cutbank Shale, dark gray, carbonaceous, east side of Big Muddy Creek and roadcut east thinly laminated, soft and of bridge, NE% NE% see. 17, T. 5 N., R. 8 E., plastic when wet; coal hori- Sailor Springs quadrangle, Jasper County. zon? ...... Shale, greenish gray and olive- Type outcrop of the Bogota Limestone Member. gray, smooth, fairly well lami- (ft) (in) nated, soft and plastic when Thickness: wet ...... Pennsylcnnian Syitem Limestone, gray and light green- McLeansboro Group ish gray; cone-in-cone struc- Mattoon Formation ture well developed .... Bogota Limestone Member Limestone, gray and greenish Clay, greenish gray, probably gray, dense, fine-grained, hard; weathered shale; soft plastic no fossils observed. (In the when wet; abundant crinoids, area, this limestone is normally corals, etc., on weathered sur- only 2 to 3 inches thick and the face ...... 2f ILLINOIS STATE GEOLOGICAL SURVEY R. 1. 214

Thickness: (ft ) (in) Thickness: (ft) (in) Limes tone, gray, fossiliferous, Ironstone, dark gray, very fine- weathered, nodular in a fos- grained, compact, hard, non- siiiferous yellowish brown fossiliferous ...... clay matrix; nodules observ- Shale, olive to gray, noncalcare- ed up to 4 inches across . . GUS, nonsilty ...... Shale, black, fissile, not well ex- Shale, dark olive to black, thin posed, thickness uncertain . . and evenly bedded, soft, non- Interval poorly exposed appears calcareous, nonsilty .... to consist of weathered gray Shale, black, hard, fissile, non- shaleorclay ...... calcareous; conodonts; con- Shale, medium gray, well bedded, tains dark gray, noncalcareous, flakp,nonsilty ..... ironstone concretions up to 8 Limestone, very dark gray, weath- inches thick and 3 to 4 feet in ers down into a spongy mater- diameter ...... ial with fosqil casts; very im- Shale, dark gray, thin-bedded, pure, ferruginous .... siltv. noncalcareous d, .... Shale, medium dark gray, finely Shale, gray, noncalcareous, silty, sandy,fossiliferous .... evenly bedded, slightly fos- Sandstone, weathers brownish siliferous, with finely dissemi- gray, fine-grained; fossiliferous natedpyrite ...... intheupperpart. .... Shale, dull dark gray, slightly Shale, greenish gray becoming dty, evenly bedded, noncalca- medium gray downward, finely reous, with finely disseminated sandy, rather poorly bedded , pyrite; fossiliferous with an Carbonaceous streak, poorly de- abundance of Ariiculopecten . . veloped; coal horizon ... EfEngham Limestone Member Shale, greenish gray, poorly bed- Shale, olive to gray, crumbly, ded, somewhat s!ickensided . . calcareous, very fossiliferous Clay, medium gray with greenish Limestone, dull gray tinged cast, tough, silty, with abun- blue, massive in one bed, dant small limestone nodules breaking slabby; finely gran- up to 1 inch in diameter. The ular; seems to be in part lower 1 foot contains irregular composed of small limestone limestone layers that weather pebbles up to % inch in dia- into nodules similar to the lime- meter, giving the unit a con- stonebelow ...... glomeratic appearance; fos- Limestone, medium light gray, silifcrous with a predomi- hard and tough, sublithograph- nance of fossils near the base ic texture, conchoidal fracture, (Myalinn, Composita, Cho- Spirorbis netes, Productus, Etlphemus, ...... Plzarkin'onotus, Murclzisonia, Shale, medium greenish gray, Astartella (?), Lophophylli- poorly bedded, silty, some dium, small gastropods, bryo- limestone nodules in the upper zoans, crinoids, bellerophon- part similar to the limestone tid gastropods) .... above ...... Sh?le, light greenish gray, much Sandstone, weathers brownish iron-stained in -,part. thinly gray, calcareous, thin-bedded, laminated, soft, clayey, with micaceous ...... carbonaceous (almost coaly) layers %-inch thick at the top, Total 3 inches from top, and at base; coalhorizon(?) ..... Clay, greenish gray, very silty, carbonaceous, calcareous; Geologic section lOF (modified from field grades into ...... notes of S. E. Ekblaw).-Ravine, east side of Clay, greenish gray, very silty, U. S. Route 45, tributary to Salt Creek, from with numerous granules of lime- center of west line eastward to SW% NE% stone; friable, not plastic; see. 33, T. 8 N., R. 6 E., Effingharn quadrangle, gradesinto ..... Effingham County. Clay, greenish gray, very silty, friable; limestone granules not noted ...... Type outcrop of the Effingham Limestone Member. Clay, greenish gray, stained yel- lowish brown, very calcareous, friable, with occasional small, Thickness: ("ft) t in irregular limy nodules ... Pennsylvaninn System Limestone, light gray with green- McLeansboro Group ish cast, silty, argillaceous, verj- Mattoon Formation knobby, irregular.surface . . 1 Shale, olive to gray, noncalcare- Sandstone, gray, micaceous, cal- om, nonsilty ...... 8-t careous in part, shaly ... 4f TYPE AND REFERENCE SECTIONS

Thickness: (ft ) (in) Thickness: (Note: Sandstone exposed about ?,& mi!e downstream Shale, black, fissile, hard . . . prohabl y immediately underlies above descri b- Limestone, shaly, dull gray to ed section.) bluish gray, massive, slabby; nodules in green clay matrix; Sandstone, gray, micaceous, un- base concealed; very fossilifer- evenly bedded, thin-bedded to ous, with M-valina, Derby ia, massive, beds 1 to 2 feet thick, Phricodothyris, Composita, Fu- ripple marks common . . . 12f sulinn, Lophophv!lidiurn, Punc- tospirifer, Chonetes yranrtliftr, 'Total 28& 1 Orthoceras, crinoids, bryozoans Shale, gr?y, calcareous, interbed- ded wlth black, noncalcareous Geologic section 10G (modified from field shale ...... notes of S. E. Ekblaw).-Roadcut and north- Coal, contains lenses of gray, cal- facing bank of Shoal Creek, SE1A SE% SW% careous shale in top 1 inch . . see. 26, T. 9 N., R. 5 E., Effingham quadrangle, Clay, gray, with purplish cast, Effingham County. noncalcareous . . . . . Clay, dark gray, nonca!careous, Type outcrop of the Shumway Limestone Memher. blocky ...... Clay, light gray tinged blue, Thickness: with a few scattered gray cal- Pennsylvanian System careous concretions; nonsandy, McLeansboro Group noncalcareous . . . . . Mattoon Formation Clay, dark gray with purplish cast Sandstone, clive to brownish gray, Clay, olive, hlocky, noncalcareous micaceous, very calcareous, un-- Clay, olive mottled with light evenly bedded, weathering nod- olive, stained brown in upper ular ...... portion, blocky, calcareous . . Shale, light olive, sandy, noncal- Limestone, greenish gray, fresh- careous. fairly evenly bedded water type. somewhat sandy, Covered interval . .' . . . massive, uneven upper surface; Shale, dark olive, evenly bedded, nodules in green clay matrix; nonsandy, noncalcareous; be- in bed of creek; base concealed comes soft in upper part . . Shale, olive, evenly and thinly Total 40 4f bedded, noncalcareous, non- sandy, with some scattered ironstone concretions up to 1 inch thick and 3 inches in diam- Geologic section 10H.-Northwest corner of eter that weather yellowish pit and highwall of abandoned limestone quarry brown; becomes fossi!iferous and in small ravine just west of this point; inlowerlto2feet . . . . NW% NW% NE% see. 30, T. 3 N., R. 4 W., Shale, olive, weathering reddish Salem quadrangle, Marion County. brown, calcareous, crumbly, fossiliferous with an abundance Type outcrop of the Omega Limestone. of Phricodothyris, crinoids, and Aoicdopecten ...... Thickness: (ft) (in) Shumway Limestone Memher Pennsylvanian Shystem Limestone, shaly, olive-gray, McLeans boro Group weathering reddish brown, calcareous, somewhat Mattoon Formation bedded; very fossiliferous, Iron-oxide enriched clay nodules, c o n t a i n i n g Phricodothyris, irregular in shape; in clay Crurithyris, productids, Der- matrix ...... b-via, Lophophvllidium . . Clay, olive, with some black Limestone, dull gray, weather- manganese staining, relatively ing ye!lowish brown, fine- firm, friable; some faint laminae grained, compact, hard, mas- near the base; occasional slip sive; thickens upstream into fractures ...... a massive bed 1 foot thick; Shale, olive, fairly well laminated, fossili ferous w i t h Phrico- with manganese staining prom- dothyris, Crurith-yris, produc- inent on partings . . . . tids, Dertyia, Composita, Hustedia, LophophyIlidium . Sideritic band, brown, much Shale, olive to dark olive, evenly weathered ...... bedded, slightly fossili ferous, Shale, olive, fairly well laminated; noncalcareous, nonsandy . . s o m e manganese staining; Shale, dark gray to black, tinged weathers soft; becomes very brown, noncalcareous, thin and thinly laminated with numer- evenly bedded, soft . . . . ous silt laminae in lower part . ILLIhTOIS STA TE GEOLOGICAL SURVEY R. I. 214

Thickness: Thickness: (ft ) (in) Siltstone, light greenish gray to Pennsylvanian Systern light gray, thinly and irregu- McLeansboro Group larly interlaminated with thin Mattoon Formation clay, coarsely micacepus on Shale, brownish gray, sandy, some partings; conta~ns oc- poorly exposed in roadcut . . 7f casional weathered sideritic and Bonpas Limestone Member, med- silty nodules; sharp contact to ium gray, weathers with a red- top oflimestone below . . . dish cast; dense to finely crys- Omega Limes tone Member ta!line, thick-bedded, weathkr- Limestone, light gray, mottled ing slabby; tends to be shaly with brown, massive; very in lower part; abundant poor- fossiliferous with very num- ly preserved fossils . . . . 3 erous fusulinids, occasional Calhoun Coal Member . . . I 1 large brachiopods and other Underclay, medium gray, soft, invertebrates; fusulinids most plastic when wet, not well ex- abundant fossils in most of posed ...... 1+ the rock; weathers to light reddish brown matrix (70 percent) with light gray ir- regular masses (30 percent) . Limestone, light gray, dense, massive, much less fossilifer- Geologic section 10J (modified from the field ous than above; brachiopods mtes of J. M. Schopf).-McCleary's Bluff out- predominate; only occasional c~opexposure NWl/ SW% SEX see. 29, T. 2 fusulinids; base concealed at S., R. 13 W., Wabash County, Illinois. pointmeasured . . . . Shale, light greenish gray, some Type outcrop of McCleary's Bluff Coal Member. pink and tan staining, very fossiliferous; well preserved Thickness: (ft) (in1 fossils weather out of shale; Pennsylvanian System occasional lenses of very fos- sili ferous limestone that in- McLeansboro Group Mattoon Formation crease in number toward the Covered hill slope top ...... Shale, medium gray to buff, be- Coal smut band, clayey, irregu- coming silty and flaky at bot- lar in thickness from a part- tom of the interval . . . . 20+ ing up to 1 inch thick; appears Coal, banded ...... 1 ' 5 tobepersistent . . . . . Underclay, white mottled . . . 1 Clay, light greenish gray, plas- Shale, black, fissile . . . . . 54 tic when wet, with carbonized Siltstone, medium gray, clayey, plant roots; several coaly smut iron-stained; grading into silt- bands up to g-inch thick but stone, clayey, light medium irregular and discontinuous . . gray, iron oxide joint filling, Clay, light greenish gray, faint iron-stained, irregularly thin- suggestion of lamination; car- bedded...... 6 bonized plant roots; soft and Shale, dark to black, flaky with plastic when wet; irregular vitrainstreaks . . . . . 9 limestone nodules about 1 inch McCleary's Eluff Coal with a x- in diameter weather out of clay . inch clay parting; top of the Shale, light olive-gray, slight1y coal is canneloid . . . . . 3 siltv. fairlv well laminated iron Underclay, whits to light gray, .stain on jbints and some bed- hard ...... 3 ding surfaces; weathers soft and Underclay, medium gray, crum- clayey; base concealed below bly, with small limestone creeklevel pisolites ...... 2 ...... ilnderclay, shnly, light gray with 'Total ironstone joint bands . . . 5 Sandstone, shaly; siltstone and silty sandstone, thin-bedded . 5 6 Siltstone, medium gray, platy; Geologic section 10 I.-Exposure in roadcut with sandstone, thin-bedded, ripple-marked in part, light of north-south road south of east-flowing trib- gray to light buff, iron-stained. utary to Bonpas Creek, NE% NE% NE% sec. (To river level to the south) . 20 6, T. 2 N., R. 14 W., Olney quadrangle, Rich- land County. (Estimated position of Friendsville Coal about 15 feet helow.) 'Type outcrops of the Bonpas Limestone Member and the Calhoun Coal Member. TYPE AND REFERENCE SECTIONS 83

Geologic section 10K (modified from field Thickness: (inj notes of M. W. Fuller) .-Exposure in quarry Bond Formation NEX see. 1, T. I1 N., R. 12 W., Marshall quad- Livingston Limestone Member rangle, Clark County. T,imestone, grayish white, mot- tled gray and white, hard, Type outcrop of the Cohn Coal Member. dense, subcrystalline, fossilif- erous, with numerous Com- Thickndss: (ft ) posita ...... t Shale, dark gray, poorly bed- Ptnnsyluanian System ded, slickensided; contains McLeansboro Group a few plant fossils ... 8 Mattoon Formation Coal, good...... 0-3 Sandstone, yellowish brown, very Shale or underclay, dark gray, ferruginous, soft, massive to slickensided, poor!y bedded 9 thin-bedded, cross-bedded, very Limestone, grayish white, hard, dirty, somewhat conglomeratic, massive; breaks with a con- micaceous; contains consider- choidal fracture: macrofos- able carbonaceous material . . sils seem to be absent; Shale, !ight to medium gray, "wheat-grain" s t r u c t u r e clayey, very soft, thin-bedded; probably due to microfocsils . contains sideritic concretion fragments ...... Shale with mudcrack network; cracks filled with iron car- bonate; Estheria found in the small depression between the cracks ...... Geologic section 11.-W. H. Krohn-Claud Shale, medium bluish gray, poorly Smith No. 1 well, SEX SEX SEX see. 10, T. bedded ...... 4 N., R. 5 E., Edgewood quadrangle, Clay Shale, black, possibly a coal hori- County, elevation 529 feet. Coal Section con- zon ...... trol well 191. Sample set 11257 studied by M. Shale, medium olive-gray; con- B. Rolley. tains minute structures re- sembling fossils ..... Covered interval ..... Reference section of the Mattoon Formation. Shale, olive-gray, soft, clayey, well bedded, with a ferruginou., Thickness L)ep/~ band at base ...... Shale, medium gray, poorly bed- ded, slightly silty, slightly mi- Penmylvanian System caceous; contains very small McLeansboro Group pebbles; fossiliferous, with os- Mattoon Format~on tracodes ...... No record ...... Shale, light gray with greenish Omega Limestone Member (re- cast, poorly bedded, soft; con- ported by dri!ler) .... tains calcareous concretions . No record ...... Limestone, freshwater type (?I, Clay, light gray, greenish gray, medium gray, argillaceous, limestone concretions ... hard, massive to nodular, fob- Shale, !ight gray, clay-li!:e; numer- siliferous, with numerous Spi- ous sideritic concretion fray- rob ...... ments ...... Clay or shale, light to medium Siltstone, light gray, very mi- olive-gray, very poorly bedded; caceous, ca!careous; sideritic contains rounded, weathered, concretion fragments ... ferruginous concretions ... Shale, dark gray to black, very Cohn Coal Member, shaly ... m:caceous, carbonaceous, pj7- Underclay, medium gray, with ritic ...... small rounded concretions in Shale, light gray, micaceous, c'ir- the lower part ..... bona ceous ...... Underclay, greenish gray, like Shale, dark gray to black, mica- above ...... ceous, carbonaceous, pyritic . Shale, olive-green, clayey, thin- Coal ...... bedded; becomes sandy toward Sandstone, white, coherent, fine, base; contains many ironstone micaceous, very carbonaceous; layers ...... thin coal laminae .... Sandstone, light bluish gray, very Shale,black;andcoal .... calcareous, fine-grained, slight- Clay, light gray, greenish gray, lv micaceous, rather nodular calcareous ...... andthin-bedded ..... Limestone, light gray to buff, slightly granular to sublitho- graphic ...... ILLINOIS STATE GEOLOGICAL SURVEY R. 1. 214

Thickness: Thickness: (jt) (in) Clay, light gray, micaceous, cal- Shale, light gray to brownish careous ...... gray, finely micaceous and car- Siltstone, light gray, fine to bonaceous: sideritic concretion coarse, very micaceous; siderit- fragments ...... 25 310 ic concretion fragments ... Shale, black ...... 2 312 Sandstone, light gray, coherent, Coal...... 2 314 fine, micaceous, carbonaceous; Shale, light gray, very micaceous many sideritic concretion frag- and carbonaceous, sideritic . . 11 325 ments ...... Siltstone, light gray to white, fine Shale, light gray, finely micace- to coarse, micaceous, carbona- ous, carbonaceous, with sid- ceous ...... 11 336 eritic concretion fragments . . Shale, black; coal streak ... 1 337 Shale, black ...... Underclay ...... 1 338 Coal ...... Siltstone, light gray to white, fine Underclay ...... to coarse; grading into sand- Siltstone, light gray to white, stone, light gray to white, co- micaceous, with siderite spher- herent, very fine, finely micace- ules ...... ous, carbonaceous, slightly cal- Shale, light gray to brownish careous: siderite concretion gray, finely micaceous, carbo- fragments ...... 12 350 naceous; shale, dark gray to Clay, light gray, very micaceous, black, micaceous, carbonaceous, with light gray to white lime- fossiliferous ...... stone concretions .....10 360 Shale, black ...... Coal, with calcite ..... Total 300 Siltstone, light gray, micaceous, very carbonaceous .... Sandstone, light gray, coherent, Bond Formation fine, micaceous, carbonaceous, Millersville Limestone Member shaly; sideritic concretion frag- Limestone, light gray to white ments ...... to buff, finely crystalline . . 8 368

1~1~1~01~STATEGEOLOGICAL SURVEY REPORT OF ~NVES'L'IGA'ITONS214 84 p., 1 pl., 4 figs., 3 tables, 1960