Shoshone Canyon
Entrance to Shoshone Canyon west of Cody on U.S. Highway 14/16/20

Shoshone Canyon is a gorge cut across Rattlesnake Mountain by the wearing action of the Shoshone River over a long period of time. The mountain is an upfold in the earth’s crust. Beds of sedimentary rock on the east flank slope eastward beneath the plains. The same units bend up and over the crest of the mountain and stand vertical along the west flank. Granite over two billion years old, is exposed around Buffalo Bill Dam. South of the dam is a vertical fracture, or fault, in the rocks along which the mountain was uplifted over 2,000 feet.