By: T. F. Lawton and M. P. Weiss
The Wales quadrangle lies in a region of structural transition between the extended lithosphere of the Basin and Range and the moderately deformed Colorado Plateau. In Late Cretaceous time, this region was the leading edge of the Sevier orogenic belt. Bedrock strata exposed within the quadrangle are from Middle Jurassic through late Eocene in age. Jurassic strata antedate Sevier deformation and are present within a zone of imbricate reverse faults along the eastern foot of the San Pitch Mountains, where the strata have a maximum thickness of 1,400 feet. Cretaceous strata deposited in a foreland basin associated with the Sevier orogenic belt are present in outcrop and in the subsurface in the southeastern part of the quadrangle. Although truncated by subsequent erosion, this part of the Cretaceous section is about 3,540 feet thick. These strata were also deformed by Sevier shortening which created the reverse faults in Jurassic beds.
Pages: 29 p.
Plates: 2 pl.
Location: Juab County and Sanpete County
Media Type: Paper Map