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Eardley Pool sits near the mouth of Eardley Canyon, in Utah's San Rafael Reef at the eastern edge of the San Rafael Swell.<br />
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The swell, approximately 75 miles (121 km) by 40 miles (64 km), consists of a giant dome-shaped anticline  of sandstone, shale, and limestone that was pushed up millions of years ago. Since that time, infrequent but powerful flash floods have eroded the sedimentary rocks into numerous valleys, canyons, gorges, mesas and buttes.