Thorne Cave, northeastern Utah: Geology

Geologic interest in Thorne Cave stems from its link with valley alluvium along Cliff Creek, which accumulated to a height of 48 ft., continued to build up another 13 ft. while men lived here, and then reached 30 ft. higher-sealing in the signs of man. Mineralogic study shows that ground water then circulated through the cave deposits for a considerable time. The alluvium is correlated with the lower part of the Tsegi Formation of the Navajo country. Cutting of a terrace at mid-depth in the valley alluvium reopened Thorne Cave, probably before the Christian era, and desert varnish then began to form on the cave brow. Radiocarbon dates from presumably correlative deposits suggest that the cave debris is about 4000 years old-a conclusion consistent with dates of 4230 and 4170 years from Thorne Cave.