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RI0008D. Geology of the Barrilla Mountains, Texas, by G. K. Eifler, Jr. 15 p., 1 figure, 2 pls. Reprinted from Geological Society of America Bulletin, v. 62, no. 4, 1951. Downloadable PDF.
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The Barrilla Mountains, in the northeastern part of the Davis Mountains of Trans-Pecos Texas, are composed of Tertiary volcanic materials. Five tuffs and five lava flows, 1500 feet thick occurring throughout the mountains, persist in thickness and lithologic characteristics. Their upper surfaces show little erosion. The lavas are chiefly Silicic and soda rich.
The volcanic succession is underlain by a Tertiary sandstone above Upper Cretaceous marine formations. These were slightly deformed by the Laramide revolution, subsequently beveled, and everywhere covered by the sands of coalescing streams. The sandstone contains well-rounded chert and quartzite pebbles. Broad folds and normal faults succeeded the extrusions of the youngest lava.
Keywords: Barrilla Mountains, Davis Mountains, stratigraphy, strata, Texas, West Texas
Introduction and acknowledgments
McCutcheon volcanic series
Age and correlation
Star Mountain rhyolite
Seven Springs formation
Petrography, by Kathryn O. Dickson
Riebeckite soda rhyolite porphyry
Spherulitic riebeckite soda granophyre
Granophyric rhyolite porphyry
Soda rhyolitic vitrophyre
Soda trachyte porphyry
Porphyritic olivine trachydolerite
Basalt and trachybasalt porphyry
Vitric rhyolite porphyry or vitrolithic tuff
1. Index map showing location of Barrilla Mountains
1. Geologic map and structure section of Barrilla Mountains, Texas
2. Jeff conglomerate southwest of Jeff ranch
1. Petrography of igneous rocks, Barrilla Mountains
Eifler, G. K., Jr., 1951, Geology of the Barrilla Mountains, Texas: The University of Texas at Austin, Bureau of Economic Geology, Report of Investigations No. 8, 15 p.