GEOLOGIC MAP OF THE CHARLESTON QUADRANGLE, WASATCH COUNTY, UTAH
Robert F. Biek and Mike Lowe
The Charleston quadrangle lies on the south edge of a structural and topographic saddle between the Wasatch Range and Uinta Mountains. The quadrangle includes the southern part of Heber City and Heber Valley and the northern half of Round Valley, as well as parts of Deer Creek Reservoir and Wasatch Mountain State Park. The quadrangle also straddles the north edge of the Charleston-Nebo thrust plate, and thus includes three distinct groups of rocks: (1) a nearly complete section of Pennsylvanian rocks of the Oquirrh Formation that comprises the Charleston thrust plate; (2) underlying, southeast-dipping Jurassic and Triassic strata below the Charleston thrust; and (3) Upper Proterozoic, Cambrian, and Mississippian strata that are exposed in a structurally complicated zone between the Charleston thrust and Deer Creek detachment faults.
A variety of late Tertiary and Quaternary deposits record the evolution of the present landscape.
This geologic map and report provide basic geologic information necessary to further evaluate geologic hazards and resources in the area, and to gain an understanding of the geology upon which this landscape developed.
CD (28 p., 2 pl., 1:24,000)
Geologic Information: The area around Cascade Springs is underlain by coarse-grained glacial sediment deposited when glaciers covered high elevations of the Wasatch Range approximately 30,000 to 10,000 years ago.
Beneath the glacial deposits, bedrock consists of Cambrian-age (about 500 million years old) quartzite, shale, sandstone, and limestone. These rocks were transported eastward 30 to 50 miles during low-angle faulting on the Charleston-Nebo thrust fault around 80 million years ago. As a result of the faulting, the bedrock in the vicinity of the springs is tilted and highly fractured.