massive to cross-bedded, generally arkosic sand, silt and gravel, locally cemented with calcium carbonate; also contains limestone, volcanic ash, diatomaceous marl, opaline sandstone and bentonitic clay
Thin bedded gray to brownish gray shale; contains concretions, selenite crystals, thin beds of bentonite and locally chalky beds.
unconsolidated sand, silt, clay, and gravel
Interbedded, soft, light-gray calcareous shale and chalk
Includes dune sand and silt and Peoria Loess
Loose to well-cemented sand and gravel