Cody Shale
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: 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.