Geologic map of the Crater Island NW quadrangle, Box Elder County, Utah (M-145)

By: D. M. Miller

The Crater Island NW quadrangle lies in northwestern Utah and includes part of the central Pilot Range and a broad, east-sloping piedmont. Late Proterozoic and Cambrian rocks arc exposed in the Pilot Range in the southwest part of the quadrangle. These rocks were metamorphosed and folded during the Mesozoic and intruded by a large, latest Eocene granitoid pluton that underlies much of the northwestern part of the quadrangle. Faulted above the granitoid pluton and underlying much of the eastern part of the quadrangle is a sequence of Eocene to Miocene volcanic and sedimentary rocks. Widespread alluvial-fan deposits unconformably overlie the Tertiary and older rocks. During late Pleistocene time, Lake Bonneville inundated much of the quadrangle; shorelines cut into older alluvial aprons and lacustrine deposits indicate that the lake surface reached a maximum altitude of about 1,590 m, including later isostatic rebound.

Other Information:
Published: 1993
Pages: 13 p.
Plates: 2 pl.
Scale: 1:24,000
Location: Box Elder County
Media Type: Paper Map