Loose to well-cemented sand and gravel
Includes dune sand and silt and Peoria Loess
Includes Piney Creek Alluvium and younger deposits
Pierre Shale--Upper unit
eolian silts
In Boulder-Fort Collins area, contains Richard, Larimer, Rocky Ridge, Terry, and Hygiene Sandstone Members; elsewhere shale between zones of Baculites reesidei and B. scotti
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
unconsolidated sand, silt, clay, and gravel