Cody Shale
Introduction 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 that vary regionally. Alphabetically:*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)Certain members rise to formation rank in other areas; for example, the Greenhorn is classified as a formation in a number of states, particularly in Colorado and Kansas.
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