Date of Award
Master of Science - Geology
Dr. Kevin Stafford
Dr. Wesley Brown
Dr. Matthew McBroom
Karst development in the Edwards Aquifer has been significantly studied in the San Antonio and Barton Spring Segments; however, karst development remains poorly studied in the Northern Segment. Detailed characterization of the Northern Segment is vital for future water conservation because of increasing urban sprawl along the Interstate 35 corridor. The Northern Segment of the Edwards Aquifer consists of Lower Cretaceous strata of the Comanche Peak, Edwards, and Georgetown formations. The stratigraphy is dominated by Edwards Limestone as it is the only formation that crops out in the study area.
Karst, stratigraphic, GIS, and geochemical studies were conducted to evaluate development of karst and hydrogeology in the Salado Creek Watershed. GIS analyses included interpretations of digital elevation models derived from LiDAR data of the study area. Karst features found in the study area were analyzed and mapped as an assessment of the speleogenesis of specific features. Stratigraphic analyses found there are eight facies total on Critchfield Ranch ranging from low-energy depositional environments with the mudstones and wackestones to high-energy depositional environments with the packstones and grainstones. One facies found has a high vuggy porosity that limits cave development in the area, but promotes development of significant high permeability horizons. Geochemistry data suggested that there is a longer residence time of groundwater between the springs based on the differences in their chemistries. Of the three caves found on Critchfield Ranch, it was determined that they are all epigene caves with vadose and phreatic morphologies.
Landers, Ashley N., "Speleogenesis of Critchfield Bat Caves and Associated Hydrogeology of the Northern Edwards Aquifer, Williamson County, Texas" (2016). Electronic Theses and Dissertations. 40.
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