Light gray to light brown clay, sandy clay, silt, sand, and some gravels.
Gray to brown to black clay and silt of high organic content.
Gray to brown to black clay and silt of moderate organic content.
Light gray to light brown clay, sandy clay, silt, sand, and some gravels. Overlain by 1-9 meters of loess.
Gray to brownish gray clay and silty clay, reddish brown in the Red River Valley, some sand and gravel locally.
Gray to black clay of very high organic content, some peat.