Cody Shale
Encyclopedia
The Cody Shale is a Late Cretaceous
geologic formation. It is mapped in Wyoming
, Idaho
, and Montana
.
The formation is described by W.G. Pierce as follows: upper part is buff, sandy shale and thinly laminated buff sandstone; lower part is dark gray, thin-bedded marine shale.
The formation is divided into many members (alphabetical):
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
geologic formation. It is mapped in Wyoming
Wyoming
Wyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High...
, Idaho
Idaho
Idaho is a state in the Rocky Mountain area of the United States. The state's largest city and capital is Boise. Residents are called "Idahoans". Idaho was admitted to the Union on July 3, 1890, as the 43rd state....
, and Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
.
The formation is described by W.G. Pierce as follows: upper part is buff, sandy shale and thinly laminated buff sandstone; lower part is dark gray, thin-bedded marine shale.
The formation is divided into many members (alphabetical):
- Ardmore Bentonite Beds (WY)
- Belle Fourche Member (MT, WY)
- Carlile Member (MT, WY)
- Claggett Member (MT, WY)
- Eldridge Creek Member (MT)
- Gammon Ferruginous Member (MT, WY)
- Greenhorn Calcareous Member (MT)
- Niobrara Member (MT, WY)
- Sage Breaks Member (WY)
- Shannon Sandstone Member (MT, WY)
- Steele Member (WY)
- Sussex Sandstone Member (WY)
- Telegraph Creek Member (MT, WY)
- Wallace Creek Tongue (WY)