Geologic map of the Crater Island SW quadrangle, Box Elder County, Utah (M-129)
By: D. M. Miller
The Crater Island SW 7.5-minute quadrangle lies in northwestern Utah and includes part of the central Pilot Range, a broad piedmont, and part of the Pilot Valley playa. Late Proterozoic metasedimentary rocks are exposed in the Pilot Range in the western part of the quadrangle. Widespread Quaternary alluvial fan deposits form a steep piedmont extending eastward from the Pilot Range to the playa. During Pleistocene time, Lake Bonneville inundated much of the area covered by the quadrangle; shorelines cut into older alluvial aprons and lacustrine deposits indicate that the lake reached about 1589 meters at its maximum depth. Since the withdrawal of Lake Bonneville waters, periodic flooding and desiccation of the playa have maintained a flat, vegetation-free surface underlain by saline mud.
This report on the Crater Island SW quadrangle is a continuation of geologic map studies in the northwestern Utah area. Adjacent geologic quadrangles include Pilot, Lemay, Crater, Crater Island NW and Patterson Pass.
Pages: 8 p.
Plates: 2 pl.
Location: Box Elder County
Media Type: Paper Map