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POTD October 1, 2013: Cedar Mountains, Tooele County, Utah

Tabbys Peak in the Cedar Mountains, Tooele County, Utah.
Photographer: Don Clark

About 40 million years ago, magma intruded to form a large dike. While cooling, the magma shrank and fractured into a six-sided column pattern, resulting in the blocky appearance of the weathered andesite at Tabbys Peak in the Cedar Mountains, Tooele County.