Geologic units in Ottawa county, Kansas

Dakota Formation (Early Cretaceous) at surface, covers 54 % of this area

White, gray, red, brown and tan kaolinitic claystone, mudstone, shale and siltstone interbedded with grayish to yellowish brown thick lenticular sandstone beds. It also contains lignite and sandstone is commonly well cemented with iron oxide and calcite.

Alluvium (Holocene to Pleistocene) at surface, covers 22 % of this area

unconsolidated sand, silt, clay, and gravel

Kiowa Shale and Cheyenne Sandstone (Early Cretaceous) at surface, covers 14 % of this area

Kiowa Shale or FM- light -gray to black illitic shale with thin coquinoidal limestone beds at the base; sandstone lenses common. Cheyenne Sandstone- massive to crossbedded, light-gray to buff fine-grained sandstone with lenses of gray sandy shale and conglomerate.

Loess (Holocene to Pleistocene) at surface, covers 5 % of this area

eolian silts

Greenhorn Limestone and Graneros Shale (Late Cretaceous) at surface, covers 2 % of this area

Greenhorn FM- thin bedded gray, chalky limestone and calcareous shale. Graneros Shale- fissile, noncalcareous, gray shale locally contains sandstone and siltstone beds.

Alluvium (Pleistocene) at surface, covers 1 % of this area

unconsolidated sand, silt, clay, and gravel

Sumner Group (Late Permian - Cimarronian) at surface, covers 1 % of this area

Ninnescah Shale (base N)- mostly red silty shale with some gray shale , argillaceous limestone and dolomite. Wellington FM with Carlton Limestone Member (base CR)-mostly gray and some red shale with minor limestone and dolomite, siltstone, gypsum and anhydrite

Carlile Shale (Late Cretaceous) at surface, covers 0.7 % of this area

Chalky shale with bentonite and thick chalk beds, dark gray fissile shale containing septarian concretions, and fine-grained sandstone.