Niobrara and Frontier Formations, and Mowry and Thermopolis Shales

Niobrara Formation (Kn) - Light-colored limestone and gray to yellow speckled limy shale. Frontier Formation (Kf) - Gray sandstone and sandy shale. Mowry Shale (Kmr) - Silvery-gray hard siliceous shale containing abundant fish scales and bentonite beds. Thermopolis Shale - Black soft fissile shale; Muddy Sandstone Member at top.
State Wyoming
Name Niobrara and Frontier Formations, and Mowry and Thermopolis Shales
Geologic age Lower Cretaceous-Upper Cretaceous
Lithologic constituents
Major
Sedimentary > Clastic > Mudstone > Shale
Sedimentary > Carbonate > Limestone
Sedimentary > Clastic > Sandstone
Minor
Sedimentary > Clastic > Mudstone > Shale > Black-shale
Incidental
Sedimentary > Clastic > Mudstone > Claystone > Bentonite
References
NGMDB product
Counties Laramie