By: J. J. Anderson and T. C. Grant
The southern part of the Fremont Pass quadrangle is in the northeastern Markagunt Plateau, the northern part in the southeastern Tushar Mountains. These areas are in the High Plateaus subprovince which is structurally transitional between the block-faulted Basin and Range Province to the west and the more stable Colorado Plateaus of which it is a part.
The Marysvale volcanic field, one of the largest eruptive piles in the western United States, straddles the High Plateaus and extends into the Basin and Range. The Fremont Pass quadrangle in the southern part of this field contains extensive volcanic accumulations from it. These are underlain and overlain by regional and local sedimentary and volcanic units and include a large Tertiary pluton. All the rocks are cut by numerous high-angle, dip-slip faults.
Pages: 6 p.
Plates: 2 pl.
Location: Garfield County and Iron County
Media Type: Paper Map