Rising out of the plains of northeastern Wyoming, Devils Tower looms 867’ over low rolling hills of shale and sandstone.
The tower itself is composed of much harder igneous rock. Large crystals in the rock indicate slow cooling of magma, and give us clues to the Tower’s origin deep beneath the present-day land surface.
The sandstones and shales that surround Devils Tower were deposited in a shallow sea that covered western North America 225 million years ago. Long after the seas drained away and the sand and mud hardened into sandstone and shale tectonic forces drove magma upward.
Millenia of erosion stripped away the surrounding sandstone and shale, gradually revealing what was designated in 1906 as North America’s first national monument.
More information here. Photo by the author.
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