Geologic units in Adams county, Colorado

Additional scientific data in this geographic area

Eolian deposits (Quaternary) at surface, covers 27 % of this area

Includes dune sand and silt and Peoria Loess

Modern alluvium (Quaternary) at surface, covers 16 % of this area

Includes Piney Creek Alluvium and younger deposits

Denver Fm or lower part of Dawson Arkose (Tertiary-Cretaceous) at surface, covers 15 % of this area

Arkosic sandstone, shale, mudstone, conglomerate, and local coal beds

Fox Hills Sandstone (Cretaceous) at surface, covers 11 % of this area

Fox Hills Sandstone

Pierre Shale--Upper unit (Cretaceous) at surface, covers 10 % of this area

Pierre Shale--Upper unit

Gravels and alluviums (Quaternary) at surface, covers 10 % of this area

Includes Broadway and Louviers Alluviums

Denver and Arapahoe Fms (Tertiary-Cretaceous) at surface, covers 7 % of this area

Sandstone, mudstone, claystone, and conglomerate; Denver is characterized by andesitic materials

Laramie Fm (Cretaceous) at surface, covers 4 % of this area

Shale, claystone, sandstone, and major coal beds

Older gravels and alluviums (Quaternary) at surface, covers 1 % of this area

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