Fine crystalline, silty, cherty dolomite, and oolitic chert with local sandstone beds.
Keokuk Limestone, Burlington Limestone, Elsey Formation, Reeds Spring Formation, Pierson Limestone, Fern Glen Formation.
Cyclic deposits, shale and limestone with sandstone, clay and several coal beds, some workable.
Cabaniss Subgroup - cyclic deposits, shale, sandstone, clay and several workable coal beds. Krebs Subgroup - cyclic deposits, sandstone, siltstone, shale, clay and some workable coal beds.
Sandstone, chert and interbedded dolomite
Alluvium - clay, silt, sand, and gravel.
Coarse - crystalline cherty dolomite with a basal Gunter Sandstone Member.
Cyclic deposits, limestone and shale with minor sandstone and coal.
Shale, clay, coal. Burgner Formation - limestone.
St. Louis Limestone, Salem Formation, Warsaw Formation.
Eminence Dolomite - dolomite with some druse - coated chert. Potosi Dolomite - dolomite with abundance of druse - coated chert.
Dominantly shale and sandstone with minor coal.
Cyclic deposits of limestone and shale.
Northview Shale, Sedalia Formation, Compton Limestone, Bachelor Formation Chouteau Group, Hannibal Shale, Horton Creek Limestone.
Cyclic deposits, limestone and shale with sandstone and siltstone.
Cyclic deposits, principally shale, sitlstone, sandstone with thin limestone beds and minor coal.
Cyclic deposits, dominantly shale with sandstone, and limestone.
Derby-Doerun Dolomite - alternating thin dolomite, siltstone, and shale; Davis Formation - glauconitic shale with fine - grained sandstone, limestone, and dolomite); Bonneterre Dolomite - dolomite, dolomitic limestone, and limestone; glauconitic in lower part.
Decorah Group, Plattin Group
Leemon Formation, Maquoketa Group including: (Girardeau Limestone, Orchard Creek Shale, Thebes Sandstone, Cape La Croix Shale), Cape Limestone, Kimmswick Limestone, Noix-Cyrene Limestone, Maquoketa Shale.
St. Peter Sandstone, Everton Formation
Chattanooga Shale, Sylamore Sandstone, Fortune Formation, Holts Summit Sandstone, Snyder Creek Shale, Cedar Valley Limestone, Louisiana Limestone, Saverton Shale, Grassy Creek Shale, Turpin Sandstone, Bushberg Sandstone, Glen Park Limestone, St. Larent Limestone, Beauvais Sandstone, Grand Tower Limestone, Clear Creek Chert, Little Saline Limestone, Grassy Knob Chert, Bailey Formation.
Chiefly alkali rhyolitic ash - flow tuffs, lava flows, and bedded tuffs, with minor trachytes.
Weldon River-Warrensburg-Moberly Channel Sandstone.
Sandstone with some dolomitic and shaly lenses; coarse - graines to conglomeratic and arkosic at base.
Joachim Dolomite, Dutchtown Formation
Undifferentiated (Ordovician rocks)
St. Francois Mountains intrusive suite (subvolcanic, alkali granitic ring complexes).
Pliocene series - Mounds Gravel (Lafayette Formation) - ferruginous, chert gravel, max of 60 ft. Eocene series - Wilcox group - includes Holly Springs Formation - bedded sandstone, clay and gravel, max of 1200 ft.; Ackerman Formation - clay with lens of sand and gravel, max of 100ft. Paleocene series - Midway Group - includes Porters Creek Clay - bentonitic clay, max of 200 ft.; Clayton Formation - marl, fossiliferous, calcareous, limonitic, glauconitic sand and clay, max of 20 ft.
Owl Creek Formation - massive, sandy, micaceous, fossilliferous, glauconitic marine clay, max 100 ft. McNairy Formation - unconsolidated sandstone with clay and gravel lenses, max of 250 ft.
Joliet Limestone, Bowling Green Dolomite, Bryant Knob Formation, Bainbridge Formation, Sexton Creek Limestone.
Fayetteville Formation, Batesville Formation, Hindville Limestone, Vienna Limestone, Tar Springs Sandstone, Glen Dean Formation, Hardinsburg Formation, Golconda Formation, Cypress Formation, Paint Creek Formation, Yankeetown Sandstone, Renault Formation, Aux Vases Sandstone, Ste. Genevieve Limestone.
Cotter and Jefferson City Dolomites
Diabase dikes and sills.
unconsolidated sand, silt, clay, and gravel
Alluvial deposits of local streams or of overbank flow of major streams - In some areas includes deposits in abandoned meanders of major streams
Alluvial deposits on one or more terrace levels
Kimmswick (Trenton) Limestone and Decorah Formation in southern and western Illinois.
Meppen Limestone, Fern Glen Formation, and Burlington-Keokuk Limestone.
Ancell Group, includes St. Peter Sandstone, Dutchtown Limestone, Joachim Dolomite, and Glenwood Formation; includes Prairie du Chien Group in Jo Daviess County of northwestern Illinois.
Sand, silt, clay, and gravel. In flood plain of Mississippi River more than 100 feet thick; in smaller streams generally less than 20 feet thick.
TULSA- "Keokuk Formation," chert and limestone. "Reeds Spring Formation," chert and limestone. "St. Joe Group," limestone and shale. FORT SMITH- Mkr "Keokuk Formation," chert; "Reeds Spring Formation," chert and limestone; and "St. Joe 'Group,'" limestone and marlstone.
St. Louis Limestone.
Interval includes Howard, White Cloud, Scranton, Bern, Auburn, Emporia, Willard, Zeandale, Pillsbury, Stotler, Root formations. Primary Lithologies: shale, light to dark gray; mudstone, gray, part laminated silty to sandy. Secondary Lithologies: limestone, fossiliferous, part coated grain/Osagia; pedogenic mudstone, part red to maroon, part calcareous/nodular; siltstone to very fine sandstone. Minor: black shale; coal. Maximum thickness 320 ft (98 m) in Fremont County.
Interval includes Burlington, Keokuk, and Warsaw formations. Upper Warsaw strata locally preserved at top of interval in extreme southeast Iowa are lower Meramecian age . Primary Lithologies: dolomite, part argillaceous to shaly; dolomitic limestone, fossiliferous; fossiliferous limestone (especially crinoidal packstone-grainstone). Secondary Lithologies: glauconitic limestone/dolomite; shale, gray to green-gray, part dolomitic, part silty; chert, nodular to bedded. Minor: quartz crystals, quartz geodes, chalcedony; phosphatic dolomite/limestone (“bone bed”); siltstone, dolomitic. Lithologies noted only in northern Iowa: oolitic limestone; “sublithographic” limestone; dolomite/chert breccia. Interval is erosionally beveled beneath sub-“St. Louis” and sub-Pennsylvanian unconformities. Maximum thicknesses in northern Iowa: 85-105 ft (26-32 m). Maximum thicknesses in southern Iowa: 155-240 ft (47-73 m).
Maquoketa Formation or Group, includes Cape Limestone, Cape La Croix Shale, Thebes Sandstone, Orchard Creek Shale, Girardeau Limestone, and Leemon Formation in southern Illinois; includes Scales Shale, Fort Atkinson Limestone, Brainard Shale, and Neda Formation in northern Illinois; includes Noix Oolite in western Illinois.
Platteville Group, includes Pecatonica, Mifflin, Grand Detour, Nachusa, and Quimbys Mill Formations; includes Plattin Limestone in southwestern Illinois.
Lower Cherokee Group in southern, central, and western Iowa includes Kilbourn, Kalo, Floris formations (primarily Atokan-lower Desmoinesian, locally Morrowan at base); Raccoon Creek Group in eastern Iowa includes “Caseyville” and Tradewater formations (primarily Morrowan at most localities; locally includes Atokan-lower Desmoinesian Tradewater Formation in upper part). Primary Lithologies: shale/mudstone, light to dark gray, part silty to sandy; sandstone, very fine to medium grained; siltstone, gray. Secondary Lithologies: carbonaceous shale/mudstone, gray to black; phosphatic black shale; limestone, dense, part fossiliferous, part sandy; coal (beds locally > 2 ft). Minor: sandstone, coarse-grained to granular, part conglomeratic; mudstone, red to pink; limestone concretions (may be septarian); cone-in-cone limestone; siderite/ironstone concretions and pellets; pyrite. Maximum thicknesses Raccoon Creek Group in Muscatine-Scott counties: 230-250 ft (70-75 m). Maximum thicknesses Lower Cherokee Group across outcrop belt: 200-370 ft (60-113 m). Maximum thickness in southwest Iowa subsurface: 650 ft (200 m).
Lower Pope Group (Aux Vases Sandstone through Glen Dean Limestone).
Includes: Lost Branch FM, Memorial Shale, Lenapah Limestone (base LE), Nowata Shale, Altamont Limestone (base PA), Bandera Shale, Pawnee Limestone (base PA), Labette Shale and Fort Scott Limestone.
Interval includes Morgan School, Mouse Creek, Labette, Pawnee, Bandera, Altamont, Nowata, Lenapah, Memorial, Lost Branch formations. Primary Lithologies: shale/mudstone, light to dark gray; limestone, fossiliferous. Secondary Lithologies: mudstone, green-gray to red/maroon; shale, black, phosphatic; sandstone, very fine to medium grained. Minor: coal; siltstone, conglomerate. Maximum thicknesses: 125-175 ft (38-52 m).
Deposited mostly on terrace deposits of the second level. Younger than some terrace deposits, older than others
New Albany Shale, Blocher Shale, Sylamore Sandstone, Selmier Shale, Sweetland Creek Shale, Grassy Creek Shale, Saverton Shale, and Louisiana Limestone.
Clayton and Porters Creek Formations; Claiborne and Wilcox Formations.
Shale, sandstone, and interbedded limestone. Shale is light gray to dark gray, greenish gray, red, or black; contains very thin layers of siltstone; locally very fossiliferous, carbonaceous. Sandstone is brownish gray to yellowish gray, or gray, argillaceous , and micaceous. Limestone is dark gray to medium gray, yellowish gray, thin bedded to thick bedded; very fossiliferous. Contains coal beds less than 1 ft. thick. Approx. max thickness 300 ft
Warsaw Formation and Salem Limestone in western Illinois.
Tamms Group, includes Bailey Limestone, “Flat Gap Limestone”, Grassy Knob Chert, Backbone Limestone, and Clear Creek Formation.
Glen Park Formation, Hannibal Shale, Chouteau Limestone, McCraney Limestone, Prospect Hill Siltstone, and Starrs Cave Limestone.
Includes: Shale Hill FM (base SH), and Hepler FM. Chiefly gray to very dark gray or yellowish gray shale with sandstone members and some limestone and coal.
Silurian System undivided, includes Sexton Creek Limestone, St. Clair Limestone, and Moccasin Springs Formation in southern Illinois; includes Wilhelmi Formation, Elwood Dolomite, Kankakee Dolomite, Joliet Dolomite, Sugar Run Dolomite, and Racine Dolomite in northeastern Illinois; includes Mosalem, Tete des Morts, Blanding, Sweeney, Marcus, and Racine Dolomites in northwestern Illinois.
Includes: Lane Shale,Wyandotte Limestone (base WY), Liberty Memorial Shale, Iola Limestone (base I), Chanute Shale (base CH), Dewey Limestone, Nellie Bly FM, Cherryvale FM, Dennis Limestone (base DN), Galeburg Shale, Mound Valley Limestone, Ladore Shale, Swope Limestone (base SW), Elm Branch Shale, Hertha Limestone.
Ste. Genevieve Limestone.
Warsaw Limestone- semigranular limestone interlaminated with saccharoidal dolomite with large amounts of gray chert; glauconite occurrs in the lower part. Keokuk Limestone- white tripolitic, chert, siliceous limestone, and dolomite
Lawrence FM (base LA)- mostly gray shale and sandstone with minor red shale, coal, gray limestone and conglomerate, thickness ranges from 140ft to 250 ft. Stranger FM- five members containing sandstone, shale, and minor limestone, coal and conglomerate ranging from 100 ft. to 180 ft. thickness.
Alluvium; includes glacial deposits along the Ohio River and its tributaries west of Cannelton locks
Interval includes Prospect Hill, Chapin, Maynes Creek, and Wassonville formations; locally includes basal Crapo (“McCraney”) Formation in southeastern Iowa. Primary Lithologies: dolomite, part cherty to very cherty, part fossiliferous (Maynes Creek-Wassonville formations); limestone, skeletal to oolitic (Chapin Fm; lower Wassonville Fm/Starrs Cave Member; middle Maynes Creek/“Eagle City” member; basal Crapo Fm); siltstone (Prospect Hill Fm). Secondary Lithologies: shale, gray, silty (Prospect Hill Fm of southeastern Iowa); limestone, dense, “sublithographic” to stromatolitic (upper Maynes Creek Fm); limestone and dolomite, dense, nodular to banded, part silty (Crapo Fm). Maximum thicknesses for total interval: 100-175 ft (30-53 m). Thickness variations: Crapo (“McCraney”) Fm, 0-65 ft (20 m); Prospect Hill Fm, 0-90 ft (27 m), generally < 25 ft (8 m); Chapin Fm, 0-30 ft (9 m), generally < 10 ft (3 m); Maynes Creek Fm, 35-155 ft (11-47 m), thickest in central to northern Iowa; Wassonville Fm (southeast Iowa only), 0-70 ft (21 m), replaced to northwest by Maynes Creek and Chapin formations, beveled beneath sub-Burlington unconformity to southeast.
Interval includes Oread, Kanwaka, Lecompton, Tecumseh, Deer Creek, Calhoun, Topeka formations. Primary Lithologies: limestone, fossiliferous, part coated grain/Osagia; shale/mudstone, light to dark gray. Secondary Lithologies: pedogenic mudstone, part calcareous/nodular; siltstone to very fine sandstone; black shale, phosphatic. Minor: chert; coal, coaly shale; red-brown mudstone. Maximum thicknesses 190-220 ft (58-67 m).
Alluvial deposits of present streams and on one or more terrace levels
Chattanooga Shale (Lower Mississippian and Upper Devonian), Clifty Limestone (Middle Devonian), and Penters Chert (Lower Devonian)
Interval includes Grassy Creek Shale, Saverton Shale, “Maple Mill” Shale, English River Formation, Louisiana Limestone (Lee County only), Aplington Formation (northern and western Iowa only), Sheffield Shale (central and northern Iowa). Famennian strata onlap Lime Creek Fm to the northwest. Primary Lithologies: shale, gray to green-gray, part silty; siltstone (especially English River Fm). Secondary Lithologies: shale, olive-brown and medium to dark brown, part laminated (Grassy Creek Fm, southeast Iowa); dolomite, part fossiliferous, part cherty, part argillaceous (Aplington Fm). Minor: interstratified dolomite and limestone, part fossiliferous (Louisiana Limestone); ooidal ironstone and phosphorite; phosphatic siltstone (“bone bed”); shale, red-brown. Maximum thicknesses in outcrop belt: southeast Iowa, 135-310 ft (41-95 m), thickest in Washington, Louisa, Des Moines counties; northern and central Iowa, 25-135 ft (8-41 m).
Sand and clay
Contains lenses of gravel and clay
Muscatatuck Group, includes Grand Tower Limestone and St. Laurent (Alto and Lingle) Formation in southern Illinois; includes Detroit River Formation, Wapsipinicon Limestone, and Cedar Valley Limestone in northern and western Illinois.
Interval includes lower “St. Louis” (Meramecian) Croton and Yenruogis members; upper “St. Louis” (lower Genevievian) Verdi and Waugh members (interval does not correlate with type St. Louis of Missouri); Pella Fm (upper Genevievian); base includes Sonora Fm (Meramecian) in parts of southeast Iowa (Lee, Van Buren, Henry, Des Moines, Jefferson counties). Primary Lithologies: dolomite, part silty/sandy, part fossiliferous; limestone, part sandy to fossiliferous; part “sublithographic,” part argillaceous. Secondary Lithologies: dolomite/limestone breccia; shale/marl, green-gray, calcareous; sandstone, fine to medium-grained; siltstone; gypsum/anhydrite (south-central Iowa). Minor: limestone, oolitic; shale, gray; shale, red to pink; chert/chalcedony. Croton Member contains gypsum-anhydrite in subsurface outside of outcrop belt. Interval is erosionally beveled to locally absent beneath Pcl; Pella Formation absent over broader areas. Maximum thicknesses for total interval 60-150 ft (18-45 m); maximum thickness Pella Formation 75 ft (23 m); maximum thickness “St. Louis” Formation 75 ft (23 m); maximum thickness Sonora Formation 35 ft (11 m).
WOODWARD- Lenticular and interfingering deposits of gravel, sand, silt, and clay. Generally light-tan to gray. Thickness along major streams ranges up to 100 feet and probably averages 40 feet; along minor streams the thickness ranges up to 45 feet and probably averages 20 feet. ENID- Sand, silt, clay, and locally gravel. Maximum thickness ranges from 30 to 80 feet (9 to 24 m) along major streams and from 0 to 60 feet (0 to 18 m) along minor streams. TULSA- Gravel, sand, silt, and clay. TULSA- Gravel, sand, silt, and clay. OKLAHOMA CITY- Sand, silt, clay, and lenticular beds of gravel. Thickness ranges from about 30 to 100 feet and probably averages about 50 feet along major streams. Along minor streams, thickness ranges from a few feet to about 50 feet and probably averages about 25 feet. LAWTON- Sand, clay, and gravel as much as 50 feet (15 m) thick; Shown only along major streams and tributaries. ARDMORE-SHERMAN- Gravel, sand, silt, and clay, including low terraces; thickness, about 25 to 100 feet. McALESTER TEXARKANA- Gravel, sand, silt, and clay, including low terraces about 30 feet above channels; thickness, about 50 feet along Little River and 110 feet along Red River.
Pitkin Limestone, Fayetteville Shale (including the Wedington Sandstone member), and Batesville Sandstone (including the Hindsville Limestone Member)
TULSA- "Pitkin Formation," limestone. "Fayetteville Formation," shale and thin limestone. "Batesville Formation," fine-grained sandstone. "Hindsville Formation," limestone and shale. "Moorefield Formation," limestone, shale, and siltstone.
Includes: Cabaniss FM (base CA) with Verdigris Limestone Member (base V) and Mineral coal bed (base MC), Krebs FM with Bluejacket Sandstone Member (base BJ) and Warner Sandstone Member (base WR).
Upper Pope Group (Tar Springs Sandstone through Kinkaid Limestone).
Interval includes Pleasanton, Hertha, Elm Branch, Swope, Galesburg, Dennis formations. Primary Lithologies: limestone, fossiliferous; shale/mudstone, light to dark gray. Secondary lithologies: mudstone to siltstone, gray to green-gray; limestone, coated grain. Minor: black shale, phosphatic; red/maroon mudstone; coal; chert. Maximum thicknesses 100-130 ft (30-40 m).
Interval includes Stranger, Cass, Lawrence formations. Primary Lithologies: shale and mudstone, light to dark gray, part silt laminated. Secondary Lithologies: limestone, fossiliferous, part coated grain; siltstone to very fine sandstone; pedogenic mudstone, part red-brown, part calcareous/nodular. Minor: coal, carbonaceous shale; black shale. Maximum thicknesses 90-135 ft (27-41 m).