By: D. M. Miller and P. T. McCarthy
The Terrace Mountain West quadrangle straddles the flat land between the west part of Terrace Mountain, an isolated small mountain on the north edge of the Great Salt Lake Desert, and the east part of the Bovine Mountains. Permian rocks underlie this part of Terrace Mountain, but their identity is uncertain in many places because the rocks are highly silicified and fractured. Faults cutting these rocks are typically altered, but are only prospected in one place at Terrace Mountain, a location east of the Terrace Mountain West quadrangle. Tertiary granitoid rocks and metamorphosed wall rocks are present in the northwestern corner of the quadrangle. Miocene strata overlying the older rocks of Terrace Mountain dip westward, apparently as a result of transport across a subhorizontal fault lying on the older rocks. Similar Miocene strata may be present under alluvial deposits between the Bovine Mountains and Terrace Mountain. Quaternary alluvial, lacustrine, and eolian sediments blanket much of the quadrangle. In particular, lacustrine deposits nicely display the many shorelines of late Pleistocene Lake Bonneville.
Pages: 13 p.
Plates: 2 pl.
Location: Box Elder County
Media Type: Paper Map