Geology of Sierra Del Carmen, West Texas and Mexico: A General Geologic Framework to Support Mapping of Biologic (Botanical) Resources


The purpose of this study is to provide geologic base maps to support the mapping of biological (botanical) resources in the Sierra del Carmen, Coahuila, Mexico, and adjacent areas in Big Bend National Park, Brewster County, Texas. Sierra del Carmen, which generally trends north-northwestward, includes the eastern part of Big Bend National Park and extends southerly into adjacent Coahuila. The range, which is within the Chihuahuan Desert, rises abruptly from the desert floor and has topographic relief that exceeds 2,000 m. The terrain is rugged, and the range is marked by numerous narrow and steep-sided canyons and valleys. The stratigraphic framework of the range is one aspect that controls the distribution of vegetation throughout the area. In general, different rock types can weather into soils of different composition, and the rocks and soils may contain different amounts of moisture. Thus, different plant species may be associated with specific rock lithologies. Geologic structures such as faults, folds, and fracture zones control the position of the rock units and influence landforms, drainage directions, and canyon development. Structures may also influence the concentration and retention of surface moisture. The geologic map of this region is intended to assist other scientists, students, and interested visitors in understanding the geology of this fascinating area and in interpreting the influence of the geologic framework on related sciences. The map emphasizes bedrock and surficial units that can be important controls on the distribution of plant communities.


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