Tertiary volcanics of the western Eagle Mountains, Hudspeth County, Texas
— Jerry M. Hoffer, Bob D. Leggett, and Dan E. Verrillo

The Eagle Mountains are located in western Trans-Pecos Texas approximately 15 km southwest of Van Horn. They are bounded on the east by the Eagle Flat Bolson and to the west by the Red Light Draw Bolson (fig. 1).

The Eagle Mountains are a northwest-trending range approximately 27 km long and 10 km wide. The central part of the range is composed of Tertiary ash-flow tuffs and lavas which encircle an intrusive plug. The igneous rocks are surrounded primarily by Cretaceous clastic and carbonate rocks. Paleozoic and Precambrian rocks crop out at the northeastern margin of the range.

The range lies within a northwest-trending belt of volcanic centers in West Texas, just south of the northern Quitman cauldron. This zone of volcanic rocks is approximately coincident with the northeastern boundary of the Chihuahua Tectonic Belt. Most of these volcanic centers have been referred to as resurgent cauldrons of Oligocene age (31 to 36 m.y.) (McAnulty, 1976).