Geologic units in Union county, Iowa

Kansas City Group (Upper Pennsylvanian, middle Missourian) at surface, covers 34 % of this area

Interval includes Cherryvale, Nellie Bly, Dewie, Chanute, Iola, Liberty Memorial, Wyandotte, Lane formations. Primary Lithologies: limestone fossiliferous; shale/mudstone, light to dark gray. Secondary Lithologies: limestone, coated grain/Osagia. Minor: mudstone, red-brown to green-gray; siltstone; black shale, phosphatic; thin coal, carbonaceous shale. Maximum thicknesses 100-140 ft (30-43 m).

Douglas Group (Upper Pennsylvanian, upper Missourian-lower Virgilian) at surface, covers 30 % of this area

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).

Lansing Group (Upper Pennsylvanian, upper Missourian) at surface, covers 25 % of this area

Interval includes Plattsburg, Vilas, Stanton formations. Primary Lithologies: limestone, fossiliferous; shale/mudstone, light to dark gray. Secondary Lithologies: limestone, coated grain/Osagia; mudstone to siltstone, gray. Minor: black shale, phosphatic; mudstone, red-brown. Maximum thicknesses 45-78 ft (14-24 m).

Shawnee Group (Upper Pennsylvanian, lower-middle Virgilian) at surface, covers 8 % of this area

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).

Bronson Group (Middle to Upper Pennsylvanian, uppermost Desmoinesian-lower Missourian) at surface, covers 4 % of this area

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).