The Sheepeater Cliffs are a series of exposed cliffs made up of

columnar basalt Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90% of a ...

Yellowstone National Park Yellowstone National Park is a List of national parks of the United States, national park of the United States located in the northwest corner of Wyoming, with small portions extending into Montana and Idaho. It was established by the 42nd U ...

in the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

. The lava was deposited about 500,000 years ago during one of the periodic basaltic floods in

Yellowstone Caldera The Yellowstone Caldera, also known as the Yellowstone Plateau Volcanic Field, is a Quaternary caldera complex and volcanic plateau spanning parts of Wyoming, Idaho, and Montana. It is driven by the Yellowstone hotspot and is largely within Yel ...

, and later exposed by the

Gardner River The Gardner River (also known as the Gardiner River) is a tributary of the Yellowstone River, approximately long, in northwestern Wyoming and south central Montana in the United States. The entire river is located within Yellowstone National ...

. The cliffs are noted as a textbook example of a basaltic flow with well defined

joints A joint or articulation (or articular surface) is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole.Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw- ...

and hexagonal columns. They were named after a band of Eastern Shoshone known as '' Tukuaduka'' ( sheep eaters). Many of the exposed cliffs are located along a steep inaccessible canyon cut by the Gardner near Bunsen Peak, but some of the cliffs located just off the Grand Loop Road can be reached by car.

References

External links

National Park Service Video – Sheepeater Cliffs
Geology of Wyoming Volcanology Columnar basalts of the United States Landforms of Yellowstone National Park {{Wyoming-geo-stub