The Permian Pierce Canyon Formation is a brick-red siltstone 350 feet thick that probably was derived from a granitic source in an arid climate transported by wind, and deposited in a shallow saline lagoon. The Dewey Lake Formation and the Quartermaster Formation have essentially identical mineral assemblages and occupy the same stratigraphic position as the Pierce Canyon, so the name Pierce Canyon should be replaced by Dewey Lake. These redbeds can be distinguished from the overlying Triassic redbeds by eight distinct mineralogical differences.

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