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Sheepeaters Cliff, Yellowstone National Park

Columns of the Sheepeaters Cliff represent cooling fractures that commonly develop in lava flows. As hot lava cools, it contracts, often forming a regular set of joints perpendicular to the cooling surfaces (top, bottom, and sides). The joints may produce regular polygonal columns, plates, or irregularly shaped fragments. Such cooling features also develop in welded tuffs.

Photograph by S.R. Brantley on 20 May 2001

This lava flow is part of the Swan Lake Flat Basalt, which was erupted sometime between 320,00 and 640,000 years ago.

Photograph by S.R. Brantley on 20 May 2001

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U.S. Department of the Interior | U.S. Geological Survey URL: http://volcanoes.usgs.gov/yvo/images/20010520-127-srb_caption.html Contact Information: YVO Web Team Last Modification: Monday, March 21, 2005 (dyv)