Geologic units in Elbert county, Colorado

Additional scientific data in this geographic area

Upper part of Dawson Arkose (Tertiary) at surface, covers 22 % of this area

Arkosic sandstone, conglomerate, and shale. Includes Green Mountain Conglomerate south of Golden

Denver Fm or lower part of Dawson Arkose (Tertiary-Cretaceous) at surface, covers 19 % of this area

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

Eolian deposits (Quaternary) at surface, covers 13 % of this area

Includes dune sand and silt and Peoria Loess

Older gravels and alluviums (Quaternary) at surface, covers 11 % of this area

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

Laramie Fm (Cretaceous) at surface, covers 9 % of this area

Shale, claystone, sandstone, and major coal beds

Modern alluvium (Quaternary) at surface, covers 8 % of this area

Includes Piney Creek Alluvium and younger deposits

White River Fm or Group (Tertiary) at surface, covers 7 % of this area

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

Pierre Shale--Upper unit (Cretaceous) at surface, covers 6 % of this area

Pierre Shale--Upper unit

Fox Hills Sandstone (Cretaceous) at surface, covers 4 % of this area

Fox Hills Sandstone

Ogallala Fm (Tertiary) at surface, covers 0.7 % of this area

Loose to well-cemented sand and gravel

Wall Mountain Tuff (Tertiary) at surface, covers < 0.1 % of this area

Early ash-flow tuff of Sawatch Range provenance