Cody in Park County, Wyoming — The American West (Mountains)
Shoshone Canyon
Wyoming
Photographed By Bill Coughlin, July 25, 2015
1. Shoshone Canyon Marker
Inscription.
Shoshone Canyon is a gorge cut through Rattlesnake Mountain by the wearing action of the Shoshone River. The mountain is a northwest trending uplift in the earth’s crust that rises 3700 feet above the surrounding terrain. Beds of sedimentary rock that are exposed on the mountain’s northeast flank slope eastward beneath the plains. The same units, which range in age from 205 to 570 million years, bend up and over the crest of the mountain and stand vertically along the southwest flank. Granite exposed at the west end of the canyon at Buffalo Bill Dam is two billion years old. North of the dam, a fault (crack) in the earth’s surface lies adjacent to the steeply inclined rocks. Geologic compressive forces which formed the uplift also caused rocks to move vertically along the fault. The Rattlesnake Mountain uplift began to form 66 million years ago, approximately the same time dinosaurs became extinct. The present topographic configuration of Rattlesnake Mountain and the formation of Shoshone Canyon are due to erosional downcutting occurring over the past three million years.
Shoshone Canyon is a gorge cut through Rattlesnake Mountain by the wearing action of the Shoshone River. The mountain is a northwest trending uplift in the earth’s crust that rises 3700 feet above the surrounding terrain. Beds of sedimentary rock that are exposed on the mountain’s northeast flank slope eastward beneath the plains. The same units, which range in age from 205 to 570 million years, bend up and over the crest of the mountain and stand vertically along the southwest flank. Granite exposed at the west end of the canyon at Buffalo Bill Dam is two billion years old. North of the dam, a fault (crack) in the earth’s surface lies adjacent to the steeply inclined rocks. Geologic compressive forces which formed the uplift also caused rocks to move vertically along the fault. The Rattlesnake Mountain uplift began to form 66 million years ago, approximately the same time dinosaurs became extinct. The present topographic configuration of Rattlesnake Mountain and the formation of Shoshone Canyon are due to erosional downcutting occurring over the past three million years.
Topics. This historical marker is listed in this topic list: Natural Features.
Location. 44° 30.667′ N, 109° 8.37′ W. Marker is in Cody, Wyoming, in Park County. Marker is on W Yellowstone
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Avenue (U.S. 20), on the right when traveling west. Touch for map. Marker is in this post office area: Cody WY 82414, United States of America. Touch for directions.
Credits. This page was last revised on February 9, 2022. It was originally submitted on July 25, 2015, by Bill Coughlin of Woodland Park, New Jersey. This page has been viewed 1,298 times since then and 133 times this year. Photos:1, 2, 3, 4. submitted on July 25, 2015, by Bill Coughlin of Woodland Park, New Jersey.
