Geology of the Precambrian rocks in the southern Franklin Mountains El Paso County, Texas
The north-south trending Franklin Mountains lie in extreme west Texas, and form a drainage divide between the Mesilla Bolson on the west and the Hueco Bolson on the east. The range is a tilted horst typical of the “basin and range” physiographic province, and is entirely surrounded by unconsolidated Cenozoic deposits of sand, gravel, clay and lacustrine materials. The area studied encompasses twelve square kilometers (8 sq. mi.) on the eastern flank of the range, extending from Fusselman Canyon southward to Scenic Drive.^ Precambrian units in the area consist of two meta-sedimentary types: (1) the Castner Limestone and (2) the Lanoria Quartzite; and five igneous units: (1) the Mundy Breccia, (2) the Rhyolite Porphyry, (3) the Porphyritic Microgranite, (4) the Red Bluff Granite and (5) numerous diabase dikes and sills.^ Rocks exposed in the study area are both hydrothermally and deuterically altered, including siliceous, sericitic and hematitic alteration types. The only economic products mined are crushed rock for industrial and decorative purposes.^
James Leslie Dye,
"Geology of the Precambrian rocks in the southern Franklin Mountains El Paso County, Texas"
(January 1, 1970).
ETD Collection for University of Texas, El Paso.