Geologic units in Prowers county, Colorado

Additional scientific data in this geographic area

Ogallala Fm (Tertiary) at surface, covers 33 % of this area

Loose to well-cemented sand and gravel

Carlile Shale, Greenhorn Limestone, and Graneros Shale (Cretaceous) at surface, covers 21 % of this area

Carlile Shale, Greenhorn Limestone, and Graneros Shale

Niobrara Fm (Cretaceous) at surface, covers 13 % of this area

Calcareous shale and limestone

Dakota Sandstone and Purgatoire Fm (Cretaceous) at surface, covers 13 % of this area

Sandstone and shale

Eolian deposits (Quaternary) at surface, covers 8 % of this area

Includes dune sand and silt and Peoria Loess

Modern alluvium (Quaternary) at surface, covers 7 % of this area

Includes Piney Creek Alluvium and younger deposits

Older gravels and alluviums (Quaternary) at surface, covers 5 % of this area

Includes Slocum, Verdos, Rocky Flats, and Nussbaum Alluviums in east, and Florida, Bridgetimber, and Bayfield Gravels in southwest

Gravels and alluviums (Quaternary) at surface, covers 0.9 % of this area

Includes Broadway and Louviers Alluviums

Morrison, Ralston Creek, and Entrada (or Exeter) Fms (Jurassic) at surface, covers 0.7 % of this area

Morrison, Ralston Creek, and Entrada (or Exeter) Fms

Dockum Group (Triassic) at surface, covers < 0.1 % of this area

Red sandstone, siltstone, and local limestone

Upper Permian rocks, undivided (Permian) at surface, covers < 0.1 % of this area

Siltstone, dolomite, and sandstone; in southeast

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

unconsolidated dune sand

Middle Tertiary intrusive rocks (Tertiary) at surface, covers < 0.1 % of this area

Intermediate to felsic compositions

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

eolian silts

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

unconsolidated sand, silt, clay, and gravel

Greenhorn Limestone and Graneros Shale (Late Cretaceous) at surface, covers < 0.1 % of this area

Greenhorn FM- thin bedded gray, chalky limestone and calcareous shale. Graneros Shale- fissile, noncalcareous, gray shale locally contains sandstone and siltstone beds.

Carlile Shale (Late Cretaceous) at surface, covers < 0.1 % of this area

Chalky shale with bentonite and thick chalk beds, dark gray fissile shale containing septarian concretions, and fine-grained sandstone.