Spiral impressions in sandstone of the Shinarump conglomerate (Triassic) occur about 10 mi. N of Vernal on the southern flank of the Uinta Mountains, Utah. The impressions are 1-3 ft. in diameter and have been cut 1/4 to 1/2 in. deep into the sandstone bedding surface. The spirals may have originated from movement of a tree branch caught in a vortex or eddy current of a stream that deposited the sandstone.

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