Cody Shale

Updated on Dec 19, 2024

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Type Sedimentary Thickness 500-1000 m Primary Slate Overlies Frontier Formation		Sub-units see text Country United States Named for Cody Underlies Mesaverde Formation
Region Montana folded belt province, Central Montana uplift, Big Horn basin, Powder River basin, Wind River basin Extent Wyoming, Idaho, Montana

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):

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)