Geologic units in Morgan county, Colorado

Eolian deposits (Quaternary) at surface, covers 54 % of this area

Includes dune sand and silt and Peoria Loess

Pierre Shale--Upper unit (Cretaceous) at surface, covers 14 % of this area

Pierre Shale--Upper unit

Gravels and alluviums (Quaternary) at surface, covers 12 % of this area

Includes Broadway and Louviers Alluviums

Modern alluvium (Quaternary) at surface, covers 12 % of this area

Includes Piney Creek Alluvium and younger deposits

Fox Hills Sandstone (Cretaceous) at surface, covers 6 % of this area

Fox Hills Sandstone

Older eolian deposits (Quaternary) at surface, covers 1.0 % of this area

Includes Loveland Loess

Laramie Fm (Cretaceous) at surface, covers 0.7 % of this area

Shale, claystone, sandstone, and major coal beds

Older gravels and alluviums (Quaternary) at surface, covers 0.5 % of this area

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

White River Fm or Group (Tertiary) at surface, covers < 0.1 % of this area

East: Ashy claystone and sandstone. Includes Castle Rock Conglomerate in region southeast of Denver. Northwest: Ashy claystone in North Park