By: D. M. Miller and J. D. Schneyer
The Sunset Pass quadrangle, north of Great Salt Lake, is centered on the southern end of the North Promontory Mountains. The mountains are underlain by Pennsylvanian and Permian rocks of the Oquirrh Formation and by Miocene volcanogenic strata. Adjacent upland plains and valleys on the east are underlain by a thin Pliocene sequence of loess and alluvium, which in turn overlies tilted and eroded Miocene strata deposited in a deep basin. Hansel Valley on the west is underlain by Pennsylvanian, Permian, and Miocene strata similar to those in the North Promontory Mountains. Most faults in the quadrangle are normal faults that accommodated growth of Miocene basins. Alluvial, lacustrine, eolian, and mass-movement deposits of late Pleistocene and Holocene age overlie the faulted older units. In addition to lacustrine deposits of late Pleistocene Lake Bonneville, widespread shorelines attest to its presence. The regionally known Stansbury, Provo, and Bonneville shorelines are well represented, as are numerous locally prominent shorelines.
Pages: 14 p.
Plates: 2 pl.
Location: Box Elder County
Media Type: Paper Map