Pierre Shale--Lower unit

Sharon Springs Member (organic-rich shale and numerous bentonite beds) in lower part
State Colorado
Name Pierre Shale--Lower unit
Geologic age Cretaceous
Lithologic constituents
Major
Sedimentary > Clastic > Mudstone > Shale
Minor
Sedimentary > Clastic > Mudstone > Claystone > Bentonite (Bed)
References

Tweto, Ogden, 1979, Geologic Map of Colorado: U.S. Geological Survey Special Geologic Map, scale 1:500,000.

NGMDB product
Counties Boulder - Cheyenne - Crowley - Custer - Douglas - El Paso - Fremont - Jefferson - Kiowa - Larimer - Lincoln - Otero - Pueblo