Geologic Maps of Parts of the Gila Bend Mountains Near Woolsey Peak and Signal Mountain, Southwestern Arizona

Geologic mapping in selected parts of the Gila Bend Mountains (Figure I) was undertaken to clarify structural and stratigraphic relationships in two areas where previous mapping was of insufficient detail to resolve important geologic field relationships. Peterson and others (1989) mapped several square miles of pre-volcanic Tertiary sedimentary rock east-northeast of Woolsey Peak in the eastern Gila Bend Mountains. It is unclear from their map, however, If these rocks were significantly tilted by extensional faulting or if their deposition occurred ill response to topography produced by extensional faulting New mapping reported here (Figure 2) indicates that the sandstone and conglomerate beneath the basaltic volcanic rocks were deposited on pre-Tertiary crystalline rocks, are not significantly faulted or tilted, and may have been deposited m response to development of volcanic landforms rather than to normal faulting.Documents in the AZGS Document Repository collection are made available by the Arizona Geological Survey (AZGS) and the University Libraries at the University of Arizona. For more information about items in this collection, please contact azgs-info@email.arizona.edu