Geologic units in Fremont county, Iowa

Wabaunsee Group (Upper Pennsylvanian, middle-upper Virgilian) at surface, covers 92 % of this area

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.

Shawnee Group (Upper Pennsylvanian, lower-middle Virgilian) at surface, covers 7 % 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).

Douglas Group (Upper Pennsylvanian, upper Missourian-lower Virgilian) at surface, covers 1 % 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).

Wabaunsee Group (Late Pennsylvanian - Virgilian) at surface, covers < 0.1 % of this area

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

Lansing Group (Late Pennsylvanian - Missourian) at surface, covers < 0.1 % of this area

Limestone and shale. Limestone is dark gray to light gray, very thin bedded to massive, sandy fossiliferous, and cherty. Shale is dark gray to light gray, maroon, black, fossiliferous, and calcareous. Approx. max thickness 75 ft

Holocene series (Quaternary-Holocene Series) at surface, covers < 0.1 % of this area

Alluvium - clay, silt, sand, and gravel.

Douglas Group (Late Pennsylvanian - Virgilian) at surface, covers < 0.1 % of this area

Shale and limestone. Shale is dark gray to medium gray, red , black, fossiliferous, calcareous and locally sandy. Limestone is dark gray to light gray, thin bedded to thick bedded, fossiliferous and locally sandy. Approx. max thickness 100 ft

Wabaunsee Group (Late Pennsylvanian-Upper Series-Virgilian Stage) at surface, covers < 0.1 % of this area

Cyclic deposits, principally shale, sitlstone, sandstone with thin limestone beds and minor coal.