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Home , Burlington Limestone, Caseyville Formation, Chattanooga Shale, Clore Formation, Decorah Shale, Grand Tower Limestone

BEDROCK GEOLOGY OF ALTENBURG QUADRANGLE Institute of Natural Resource Sustainability William W. Shilts, Executive Director JACKSON COUNTY, AND PERRY COUNTY, STATEMAP Altenburg-BG ILLINOIS STATE GEOLOGICAL SURVEY E. Donald McKay III, Interim Director Mary J. Seid, Joseph A. Devera, Allen L. Weedman, and Dewey H. Amos 2009

360 GEOLOGIC UNITS

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) )

14 Qal Alluvial deposits )

13 18 and 17 360 ) 15 360 16 14 0 36

) 13 Qf Fan deposits ) Unconformity

Qal ) &

350 tl Lower Atokan )

)

360 ) &cv Morrowan

24 360 )

Unconformity ) 17 Upper Elviran undivided, Meu

) Waltersburg to top of Degonia 19 20 Qal 21 22 23

) 24

) Mv Vienna 360 o ) 3 Mts )

350 Mts Tar Springs Sandstone )

20 360 ) Mgd 360

30 )

Mgd ) 21 350 360

Mts 29 ) Qal Hardinsburg Sandstone and J N Mhg Chesterian ) Golconda Formations h Æ Qal Mav anc 28 27

Br ) N oJ 26 25 JN

85 N ) Cypress Sandstone through J Mcpc

Dsl 500 Paint Creek Formation

JN N )

J o Mts

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Dgt 600 J N 70 J N Mgd Yankeetown Formation s ) Myr Db 80 28 Æ and Renault Sandstone N J 29 N

J N ) Sb J Mgd

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Ssc 25 Clines o N 25 Msg 27 ) Qal J 80 s 3 Mav Aux Vases Sandstone N J N Mts o MILL J M I S S I S S I P P I 34 )

Qal

J N ) N J Dsl 35 N 26 J o N 25 J Mgd

Mgd ) Msg Ste. Genevieve Limestone

500

o Db DITCH J 20 Mgd N N N ) J J o R I V E R o N 600

J 80 N ) 10 o J Mav Æ Msl St. Louis Limestone

N 35 N J o J J N Ssc o N N 3 ) 36 12 J J o 35 500 Mts JN

Dc 600 Mgd ) 600 N J o50 Msg N 500

o Ok J J N N Mv N 5 N J J 34 4 35 ) Msm Og J 33 o 600 35 o N 500 N J J 32 35 N ) N J 36

Mfg J N Mgd

N J LTJ o Dsl N N 10 J J o80 Mv Mts ) AU Msl N N 500 Mw Valmeyeran o J J 31 F 10 N ) Sb o J N Mav 500 &tl J JN

Dgk N 40 J Mw N J Mhg LICKN Mkb J N Mgd ) Od N J - J N 5 500 Db 600 J 25 and H o TZ ) N N N N N J N o J J J J 32 Mkb | N J N

J J N J J N G N Mhg J Mcpc OwlNJ ) 400 600 500 NJ N N J J N ) Mfg J 5 Mav 6

) ODENSCHA Mfg o J N N Fern Glen Formation H 20 N o ) o J J ) | 35 5 B ) Qal ) G Ssc Dc N Mav 1 ) J o38 Msg N ) N Unconformity ) J 1 J &cv ) Mav

N 500

) J N J J N ) Og o Dsl 30 ) Chattanooga Shale, MO ) 40 4 2 Myr Cr N Qal 500 Dc ) Db 3 o J Upper 5 ) eek (Grassy Creek Shale, IL) ) ) ) N N H J J 500 | ) o o20 ) 20 ) N Mav G ) J Dgt N 400 )

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N 14 Db N 13 ) N J

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N Msl ) Ssc Lower Op Qal J 27

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o Op J Dsl J Msl Br 400 N azeau 400 N J Msg Unconformity

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J N N Girardeau Limestone

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J J

3 500 15

N o J o Og and o N Upper 17 J 15

o N 15 16 Db JÆ Dgt 5 JN Mav

o Unconformity N Qal

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Op 3 N 500 N 500 13 J J J N N

12 J N Ok

Op o J 23 N

8 N J NJ

J N J NJ o N o Sb Od J Unconformity Qal 400 Dsl Og N Qal 10 J o 500 3 500 N 24 J Dgt 25

500 N

Od J N Ssc J Od Middle Creek Op Dsl

400 N N

Ok J Dsl J

J

N Æ

N J 400 J N Msl o o 23 4 Op Qal N N

15 J J

Od J

N Msm 20 N Æ o 24 J Dsl 21 Dgt 400 22 10 Db N N J J

500 N

Od 500 J J N 19

500

Dbb J

Ok Æ N N

400 J J

N N Dcc

J J Dgt

Od N Dcc J 20 N

Og Ssc 600 J

520 N Db N Sb J

25 J Ok N Od 500 500 Db Symbols Op 540 500

27 26 500 25 31

Op 29 500 28 Qal J Ok N 600 30 Dgk 500 40 Strike and dip of bedding; number indicates 5 o Od o Db Dgk degree of dip A s80 Overturned bedding - showing strike and dip; number indicates degree of dip

Base map compiled by Illinois State Geological Survey from digital data (Digital Line SCALE 1:24,000 Geology based on field work and map compilation by Mary J. Seid, Joseph A. Devera, 2008– Æ Abandoned quarry Graphs) provided by the Geological Survey. Topography compiled 1946. Pla- 1 1/ 2 0 1 MILE 2009, and Allen L. Weedman, 1991. Misouri geology by Dewey H. Amos, 1985. nimetry derived from imagery taken 1993. Public Land Survey System and survey control 1000 0 1000 2000 3000 4000 5000 6000 7000 FEET current as of 1996. partial field check by U.S. Forest Service 1996. Digital cartography by Jane E.J. Domier, Steven M. Radil, and Daniel R. Stevenson, Illinois State Line Symbols 1 .5 0 1 KILOMETER Geological Survey. dashed where inferred, dotted where concealed North American Datum of 1983 (NAD 83) Projection: Transverse Mercator This research was supported in part by the U.S. Geological Survey National Cooperative Geo- 10,000-foot ticks: Illinois State Plane Coordinate system, west zone (Transverse Mercator) logic Mapping Program (STATEMAP) under USGS award number 08HQAG0084. The views and Contact 1,000-meter ticks: Universal Transverse Mercator grid system, zone 16 BASE MAP CONTOUR INTERVAL 20 FEET conclusions contained in this document are those of the authors and should not be interpreted as SUPPLEMENTARY CONTOUR INTERVAL 10 FEET necessarily representing the official policies, either expressed or implied, of the U.S. Government. Fault; bar and ball on downthrown side NATIONAL GEODETIC VERTICAL DATUM OF 1929 Recommended citation: This map has not undergone the formal Illinois Geologic Quadrangle map review process. Anticline Seid, M.J., J.A. Devera, A.L. Weedman, and D.H. Amos, 2009, Bedrock Geology of Alten- Whether or when this map will be formally reviewed and published depends on the resources and burg Quadrangle, Jackson County, Illinois and Perry County, Missouri: Illinois State priorities of the ISGS. Geological Survey, USGS-STATEMAP contract report, 2 sheets, 1:24,000, report, 3 p. © 2009 University of Illinois Board of Trustees. All rights reserved. A AЈ Line of cross section For permission information, contact the Illinois State Geological Survey. The Illinois State Geological Survey and the University of Illinois make no guarantee, expressed or implied, regarding the correctness of the interpretations presented in this document and ac- cept no liability for the consequences of decisions made by others on the basis of the information presented here. The geologic interpretations are based on data that may vary with respect to accuracy of geographic location, the type and quantity of data available at each location, and the scientific and technical qualifications of the data sources. Maps or cross sections in this document are not meant to be enlarged.

1° ROAD CLASSIFICATION ADJOINING 1 2 3 QUADRANGLES MA TR 1 Rockwood, MO NOR GNETIC Primary highway, Light-duty road, hard or UE NOR UE 2 Raddle hard surface improved surface 3 Oraville 4 5 Secondary highway, Light-duty road, dirt

4 Crosstown, MO TH hard surface

For more information contact: 5 Gorham T Unimproved road Institute of Natural Resource Sustainability 6 Oak Ridge, MO H Illinois State Geological Survey 6 7 8 7 Neelys Landing, MO 615 East Peabody Drive 8 Wolf Lake APPROXIMATE MEAN State Route County Route Champaign, Illinois 61820-6964 DECLINATION, 2009 (217) 244-2414 http://www.isgs.illinois.edu

STATEMAP Altenburg-BG Sheet 1 of 2 MEMBER THICKNESS A Alluvial deposits Sand, gravel, silt and clay. Sand is light gray present at the surface due to faulting; description from nearby areas

E AG FORMATION or GRAPHIC COLUMN (feet)

UNIT to brown-gray, coarse to fine grained, poorly sorted, ranges from and subsurface data. The Paint Creek Formationis limestone and U Grand Tower Limestone Limestone. The upper limestone is

ST BED

SERIES SYSTEM weakly stratified to well stratified. Sand and clay occur as laminae clay; light to medium gray öolitic grainstones and packstones; brown gray and thinly bedded; the basal part is light gray to medium or cross bedded channels found on the floodplains and creeks. dominated by pelmatozoa and blastoids; thin bedded to gray sandy limestone. The lower part yields thick cross bedded Gravels are angular to sub-rounded, composed of chert, quartz and lenticular; coarse grained texture; some greenish clay occurs in the limestone overlain locally by boundstones, which are composed of A rock fragments of igneous, metamorphic and local sedimentary ori- matrix between coarse bioclasts; shale in the upper portion is dark Hexagonaria and stromatoporoids. In places, a white sandstone lat-

Y Alluvium, fan, OCENE

TER- and terrace gin. Silt is brown and gray, intermixed with sands and gravels. Clay to medium gray and locally calcareous; the middle part is domi- erally grades into a light gray crinoidal grainstone. are A and deposits 0–200

NAR is gray to yellow, intermixed with sand and silt layers, and domi- nated by weakly fissile dark to medium gray shales and red beds; common—some beds are entirely composed of chonetid packstone

QU HOLOCENE

PLEIST B nantly in meander scars or oxbow lake settings. Unconformable with the basal part is light gray limestone, cross bedded, and contains facies; unconformable contact with unit below. units below. abundant pelmatozoa; some of the pelmatozoa are stained red; Paint Creek not present in this quadrangle due to faulting. V Clear Creek Chert Chert and limestone. White to light brown- Lower 100–150 C B Fan deposits Cobbles, gravel, and sand. Cobbles are com- ish yellow, thin to medium well-bedded, fossiliferous chert; can be OKAN Tradewater

posed of local bedrock deposited onto the River flood- K Yankeetown and Renault Limestone Sandstone, limestone, stained red and orange; some limestone beds occur throughout AT

plain; angular to sub-rounded, brown and gray. Sand is light brown and interbedded shale. The Yankeetown Formation is sandstone with sandy beds near the top; brachiopods and occur as ANIAN V quartz, poorly sorted, coarse to fine grained, locally containing well and shale; sandstone is light gray to reddish brown quartz arenite, internal casts; external molds and are common in some beds; verti- AN rounded quartz pebbles. This deposit originates at the mouth of well sorted, thin to thick bedded, with silty beds and cross bed- cal burrows have been observed; stylolites are prominent; locally

OW Caseyville 150–250 D large streams. Unconformable with alluvium and unit below. ded sandstones in places; bedding is undulatory or wavy and be- unconformable and sharp contact with unit below.

PENNSYL comes locally cherty; shale medium to dark gray to reddish gray;

MORR C Lower Tradewater Sandstone and shale. Sandstone is brown calcareous and silty in part; unconformable at base. The Renault W Little Saline Limestone (Backbone Limestone) Limestone. to tan, medium to fine grained, sub-rounded sublitharenite; mica, Limestone is limestone, shale and interbedded sandstone; later- White to light gray, and grainstone; cherty in the dark mineral grains, clay, and occasional well rounded quartz ally variable with all three lithologies; limestone is lime mudstone to middle part; poorly exposed due to faulting; unconformable with unit Degonia Ss pebbles and granules occur. On weathered face, iron-staining and fossil wackestone, medium to dark bluish gray, argillaceous; com- below. Clore liesegang banding are prominent. Shale is dark gray to medium mon fossils include fenestrate bryozoa, pelmatozoa and blastoids;

Formation gray, carbonaceous in part, weakly fissile, and varies from soft shale is variegated red and green; calcareous in part; sandstone is X Grassy Knob Chert Chert and limestone. Chert is white to light VIRAN Palestine Ss 100–250 E claystone to hard shale. Contact locally disconformable and sharp light brown, fine grained, well sorted and calcareous; basal part of yellowish brown, medium to thick well-bedded and occurs as chert in most areas. the formation is conglomeratic with sandstone and chert fragments; nodules; locally cemented with ferruginous material; non-fossilif- Menard unconformable at base. erous but contains horizontal burrows. Limestone is light yellowish

UPPER EL Limestone Oolite bed D Caseyville Sandstone and shale. Sandstone is tan quartz brown to gray brown argillaceous mudstone. Brecciated beds occur arenite, coarse to fine grained, well rounded to sub-rounded, and L Aux Vases Sandstone Sandstone. White to light gray, fine to in the unit probably due to dissolution; gradational contact with unit Waltersburg typically poorly sorted; however, fine to medium grained, well sorted medium grained quartz arenite, well sorted; thin to thick bedded, below. Vienna Ls 25 F quartz arenite is also observed. Rounded, white quartz pebbles cross bedded, beds can be ripple marked or laminated; calcareous Tar Springs common in places; thick to medium bedded with large scale unidi- in places near the top; greenish gray shale clasts incorporated in Y Bailey Limestone Limestone, chert and shale. Thinly bedded 90 G Sandstone rectional cross bedding, sucrosic texture, liesegang banding promi- sandstone. Prominent unconformity at base. and interbedded lime mudstone and thin shale, gray to light gray; nent on the weathered face; interstitial clay is present but localized. fossils occur in the argillaceous laminae above the thin beds of the Shale is present but not exposed. Unconformable with underlying M Ste. Genevieve Limestone Limestone. Facies range among middle and upper part, including the , Huntonia sp., tenta- units. öolitic grainstone, fossil grainstones, and packstones, light gray to culids, brachiopods, and . Chert is light gray and occurs as Glen Dean Ls 75–100 H white; thick to medium bedded; grainstones are cross bedded; white small nodules within the thin beds; siliceous sponge spicules are E Upper Elviran undivided (Degonia Sandstone, Clore For- chert nodules scattered in the middle part; important fossils include common throughout. Greenish lime mudstones, shales and light Hardinsburg Ss 20 mation, Palestine Sandstone, , Waltersburg Platycrinites penicillus, found typically as disarticulated crinoid green chert nodules occur in the lower part; unit is characterized by Haney 10 Formation) Sandstone, limestone, and shale. Sandstones are columnals. They are diagnostic and are oval shaped with calcare- thin, very regular, graded beds; unconformable at the base. light gray to tan, fine grained, well sorted; bedding varies from thin ous nodes around the periphery. The small brachiopod, Pugnoides Golconda I Fraileys 70 to massive, rhythmically laminated, ripple laminated sheets, cross ottumwa is representative. The limestone can be dolomitized near Z Bainbridge Limestone. Brick red mudstone, argillaceous or 85–110 bedded. The Degonia Sandstone is locally calcareous near the top fault zones. Basal contact was not observed. marly, commonly mottled with purple and green; weathers to a red Beech Creek 10 Cypress Ss 20 with abundant brachiopod molds and casts in the sandstone. Small residuum; weakly fissile; dense gray with pinkish gray stains in the primary sedimentary structures are characteristic. Shale is red and N St. Louis Limestone Limestone and shale. Gray to medium lower part; fossils include straight nautiloid cephalopods and dal- 60 green claystone in upper part, gray to dark gray in middle and lower gray lime-mudstone (sublithographic) displays conchoidal fracture; manitid, phacopid and calymenid trilobites; unconformable at the

CHESTERIAN parts. Marine fossils in part dominated by productid brachiopods, thick to massively bedded; white to light gray chert occurs in ovoid base. Paint Creek J Composita subquadrata, Anthracospirifer increbescens, and fenes- nodules with variegated light and dark gray banding in some. Fossil 70 trate bryozoans. are gray to dark gray lime mudstones. wackestones and rare packstones occur. Fossils, where they occur, AA Sexton Creek Limestone Cherty limestone. Light gray to 110–130 Fossil wackestones are argillaceous and display “hourglass” weath- are dominated by echinoderms, including disarticulated and com- brownish gray, cherty lime mudstone; medium to thick bedded; 20 ering. Less common are packstones and grainstones, but they can plete crinoids and echinoids. Boundstones occur in the lower part chert is tan, waxy, and observed as flat irregularly shaped nodules. occur in some beds. Öolite beds were found in both the Menard of the unit and are primarily composed of Acrocyathus proliferum In the middle part, there are tabulate and colonial corals which are Yankeetown 45 Limestone and to the east in the Gorham Quad- and Acrocyathus floriformus. Shale is medium gray, bluish gray, and conspicuous, silicified, round and domed. Unconformable with unit rangle. This unit is mapped as Upper Elviran undivided in places of green and occurs in thin beds between limestone beds. Basal con- below. K poor exposure and complex structure. Some upper units are trun- tact was not observed but is conformable with the unit below. Renault 80 95–125 cated by pre-Pennsylvanian erosion and subsequent Pennsylvanian BB Girardeau Limestone and Maquoketa Limestone, shale, Limestone cover. Basal contact is sharp but conformable with underlying unit. O Salem Limestone Limestone, shale and dolostone. The top and sandstone. The Girardeau Limestone is medium to dark gray,

part is brownish dolostone with thin gray shale partings; öolite beds dense lime mudstone; thin bedded with interbedded shale laminae; MISSISSIPPIAN F Limestone and chert. Dark gray, siliceous, occur in the upper central and lower parts; Endothyrid foraminifera undulatory bedding with gray-brown chert nodules; fossils are well Aux Vases 60–100 L weathers to a spongy rind; chert light to medium gray, occurs main- abundant in some beds; lower part was not observed due to fault- preserved below shale laminae atop lime mudstone beds; fossils Sandstone ly as a pelmatozoan wackestone. The unit is poorly exposed in the ing. include whole crinoids, trilobites, tentaculites and brachiopods; only Missouri section. Basal contact is sharp. locally exposed; unconformable with Maquoketa below. The Maquo- P Warsaw Limestone. Dominantly fossil wackestones with some keta consists of the Orchard Creek Shale, Thebes Sandstone, and G Tar Springs Sandstone Sandstone and shale. Sandstone is packstone facies; medium gray to brown; localized öolitic and dolo- Cape Limestone. The Orchard Creek Shale is shale and limestone; Ste. Genevieve light gray to tan-brown quartz arenite, can weather yellowish to mitic beds; fossils include crinoids, bryozoans, and foraminifera; silty shale is medium gray to light greenish gray, weathers brown, calcar- 130–195 M Limestone reddish brown; fine grained, well sorted, thin to thick bedded; pri- and shaly in the middle to lower parts; gradational contact with the eous; contains lenses of fossiliferous lime mudstone; fossils char- mary sedimentary structures include ripple marks, ripple laminated unit below. acteristic of this member include the trilobite Anataphrus sp. and sheets, and cross bedding; thicker bedded, cross bedded and chan- edrioasteroids; poorly exposed; gradational contact with Thebes nel form sandstones occur in the lower part. Medium gray shale and Q Keokuk Limestone and Burlington Limestone Limestone Sandstone below. The Thebes Sandstone is sandstone and shale; tan to medium brown siltstone are seen in the middle part; scat- and chert. Fossil packstones, wackestones and some öolitic grain- sandstone is greenish brown to tan, fine grained, quartz arenite; St. Louis 150–170 N tered debris is associated with the shale and siltstone. Lower stones are dominant, but few lime-mudstone beds occur. Tan to contains silt and shale in part; bedding is thin to locally thick; cross Limestone contact locally unconformable. white crinoidal grainstone facies occur in the upper section; cross bedded; greenish blue-gray calcareous siltstone occurs in places bedded; coarsely crystalline appearance, caused by disarticulated and contains a small, blind trilobite, Ampyxina bellatula, and the H Glen Dean Limestone Limestone and shale. Limestone is skeletal remains of large crinoid columnals, echinoid plates, and trace fossil, Chondrites ichnosp.; the lower part contains shale and Salem 105–140 O mostly thin, gray, wackestone facies containing öolitic packstones spines. Chert is white to light gray; chert nodules and stringers common brachiopods; unconformable with Cape Limestone below. Limestone and fossiliferous packstones; bedding is thin to medium and can become more prevalent lower in the unit; minor amounts of shale The Cape Limestone is medium to dark gray lime mudstone, sandy be tabular or undulatory and cross bedded with bioclasts; weathers occur as thin gray beds; lower contact is gradational with the under- in places, abundant crinoid columns; fossils include brachiopods from gray to tan; interbedded with dark gray, soft, calcareous shales lying unit. and locally large orthoconic cephalopods; unconformable with unit in the upper part. Fossils occur in both limestones and shales; below. Warsaw 160–210 P fossils include fenestrate bryozoans, Prismopora serratula (prism- R Fern Glen Limestone, shale, chert and dolostone. Limestone is

ALMEYERAN shaped bryozoan), Pentremites sp. (large blastoid, commonly found medium to light yellowish brown packstones and wackestones, me- CC Kimmswick Limestone and Decorah Shale Limestone and V at the Starland Quarry), Cleothyridina sp., spiriferids, productids dium to thinly bedded, typically argillaceous; contains small quartz shale interbedded. The Kimmswick is pure limestone; white crinoi- and crinoids. The lower part grades into a shale at the base. geodes in the lower beds; fossils include abundant crinoid colum- dal grainstone, pinkish in places; altered to yellowish dolomite in nals, brachiopods, bryozoans and corals. Shale is medium brown, places, especially near faults; bedding ranges from thin to thick; I Hardinsburg Sandstone and Golconda Shale, limestone, green, red and calcareous in places. Chert is light to medium brown Receptaculites oweni is a characteristic fossil alga; other fossils siltstone, and sandstone. The Hardinsburg Sandstone is dark gray and irregularly bedded. Dolostone is tan to brown, argillaceous, and include trilobites, brachiopods, and crinoids; unconformable with Keokuk and shale with poorly exposed siltstone and sandstone streaks. The dominantly medium bedded; lower contact is unconformable. Decorah Shale below. The Decorah Shale is limestone and inter- Burlington 400 Q is limestone and shale. The upper part is light bedded shale; limestone is medium gray to dark purplish gray with Limestones gray, öolitic grainstone to fossil packstone, thick to medium bedded, S Chattanooga Shale (Grassy Creek Shale) Shale. Medium to common brachiopods; shale is greenish gray, fossiliferous; Decorah locally cross bedded; numerous crinoids, blastoids, fenestrate bryo- dark brown or black, fissile; some beds are slightly silty, siliceous or is locally absent due to post Decorah or pre-Kimmswick erosion; zoans and brachiopods are present; shale is dark gray, dense, non- dolomitized; unconformable with unit below. conformable with unit below. calcareous claystone but is fossiliferous in places; the middle part of Fern Glen 55–160 R the unit contains lenticular limestones which are bryozoan-pelmato- T St. Laurent Shale, limestone, and chert. Dark gray to medium DD Plattin Limestone Limestone and chert. Light gray to light zoan wackestones to packstones; the basal unit is argillaceous and brown shale; shale grades into limestone; contains limestone lens- brown lime mudstone, sublithographic; calcite or dolostone-filled Chattanooga Sh fossiliferous wackestone containing foraminifera, gastropods and es and chert in the upper part. Limestone is dark gray, yellowish burrows are common and characteristic of the Plattin Limestone; 55–85 S (Grassy Creek Sh) bivalves; lower contact was not observed, but it is unconformable. brown, or reddish gray; ranges from argillaceous wackestones to thin to medium wavy bedded; contains greenish gray to dark gray UPPER öolitic grainstones; fossils include rugose corals, gastropods, crinoid shale interbeds. Chert is light gray to light brown; occurs in nodules J Cypress Sandstone and Paint Creek Shale, limestone, and columnals, bivalves, Eldredgops cristata (trilobite), and Microcyclus and discontinuous layers; locally fossiliferous but the lower part is St. Laurent 113–170 T claystone. The Cypress Sandstone is dark to medium gray and discus (the “button” coral, near the base); locally unconformable mostly unfossiliferous; basal contact was not observed.

greenish gray, with a few red shale beds; Cypress Sandstone not with the unit below.

GIVETIAN MIDDLE Grand Tower 175–230 U

Limestone Dutch Creek Sanstone

Clear Creek 140–165 V

ONIAN Chert DEV

South North Backbone Ls (Little Saline Ls) 175 W A AЈ Elevation WER (feet) LO Grassy Knob 210 1000 Missouri Illinois 1000 Chert X Ste. Genevieve Fault Zone &cv 500 Dbb Dslc 500 Db Mc Dgk Dgt Bailey Dcc 310 Y 0 Mc 0 Limestone Db Dbb Dgk Mv OS ? -500 Db -500 OS Mv OS Dslc Dgt Bainbridge Moccasin Springs 83–200 Z -1000 -1000

St. Clair Grand Tower Horizontal scale: 1 inch = 2,000 feet

SILURIAN &cv Dgt Dgk Caseyville Formation Limestone Grassy Knob Chert Vertical scale: 1 inch = 1,000 feet Sexton Creek Ls 30–65 AA Vertical exaggeration: 2× Chesterian Girardeau Ls 0–10 Mc Dcc Clear Creek Chert Db Bailey Limestone Orchard Creek 45 undifferentiated Thebes 25

TIAN Maquoketa BB Mv Valmeyeran Dbb Backbone (Little Ordovician and Silurian A 40 OS 100–133

CINCINN- undifferentiated Saline) Limestone Cape 3 undifferentiated Dslc St. Laurent Formation Kimmswick and Chattanooga Shale Limestone 50–165 CC

Decorah Sh

VICIAN ORDO

Plattin CHAMPLAINIAN 190 DD Limestone

STATEMAP Altenburg-BG Sheet 2 of 2