Geology of the Barrilla Mountains, Texas. Digital Download

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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ABSTRACT
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

CONTENTS

Introduction and acknowledgments

General stratigraphy

 Permian system

 Cretaceous system

             Comanche series

                         Georgetown group

             Gulf series

                         Austin group

                         Taylor group

 Tertiary system

             McCutcheon volcanic series

                         Introduction

                         Age and correlation

                         Huelster formation

                         Star Mountain rhyolite

                         Seven Springs formation

 Possible intrusions

 Structural features

             Introduction

             Folds

             Faults

Geomorphology

Economic geology

Petrography, by Kathryn O. Dickson

             General statement.

             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

References cited

Figure

 1. Index map showing location of Barrilla Mountains

 
Plates

 1. Geologic map and structure section of Barrilla Mountains, Texas

 2. Jeff conglomerate southwest of Jeff ranch

 
Table

 1. Petrography of igneous rocks, Barrilla Mountains


Citation
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.