These soils formed in more than 60 inches of loess. These are the Clarksdale , Clinton , Keomah , and Marine soils. The somewhat poorly drained Marine, Clarksdale, and Keomah soils are on slightly higher and slightly more convex parts of the summits. Poorly drained or very poorly drained. The potential for surface water runoff is low or negligible.
Permeability is very slow.
The seasonal high water table is above the surface to 1.5 feet below the surface in spring in normal years. Most areas are cultivated. Corn, soybeans, small grain, and meadow are the principal crops. Native vegetation is mixed hardwood forest. West central Illinois and southeastern Iowa in MLRA 115 and 108.