Mushroom Rock in San Rafael Swell

October 20, 2007


Provided by: JoEtta Abo
Summary authors & editors: JoEtta Abo, Stu Witmer

The mushroom shaped rock shown above was photographed in south central Utah, near the town of Green River. This area is part of the San Rafael Swell, a geologic feature containing over 2,000 square miles (5,180 sq. km) of sand, mud, clay and limestone sediments that were laid down millions of years ago. Later, near the end of the Jurassic Period (c. 150 mya), sub-surface pressure formed a dome-shaped anticline that eventually eroded to form the remarkable landscape seen today. Photo taken on March 12, 2005.

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