Geologic units in Kit Carson county, Colorado

Ogallala Fm (Tertiary) at surface, covers 71 % of this area

Loose to well-cemented sand and gravel

Eolian deposits (Quaternary) at surface, covers 25 % of this area

Includes dune sand and silt and Peoria Loess

Modern alluvium (Quaternary) at surface, covers 2 % of this area

Includes Piney Creek Alluvium and younger deposits

Pierre Shale--Upper unit (Cretaceous) at surface, covers 1 % of this area

Pierre Shale--Upper unit

Loess (Holocene to Pleistocene) at surface, covers 0.1 % of this area

eolian silts

Pierre Shale--Middle unit (Cretaceous) at surface, covers < 0.1 % of this area

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

Ogallala Formation (Miocene) at surface, covers < 0.1 % of this area

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

Alluvium (Holocene to Pleistocene) at surface, covers < 0.1 % of this area

unconsolidated sand, silt, clay, and gravel