Hypogene Processes in the Balcones Fault Zone Segment of the Edwards Aquifer of South-Central Texas

  • Geary M. SchindelEmail author
  • Marcus Gary
Part of the Cave and Karst Systems of the World book series (CAKASYWO)


The Balcones Fault Zone segment of the Edwards Aquifer of south-central Texas is one of the most important and prolific karst aquifers in the United States. It is formed within the lower Cretaceous Edwards Group Limestone. Since deposition, it has undergone subaerial exposure, burial in the upper Cretaceous, faulting, igneous intrusion, uplift in the Miocene, and weathering processes. The Balcones Fault Zone consists of mostly normal en-echelon faults with as much as 300 m of displacement striking northeast–southwest and dipping down toward the Gulf of Mexico. It forms the Contributing, Recharge, and Artesian zones of the aquifer. Karst characteristics of the Edwards Aquifer are the result of both epigene and hypogene processes, which continue today. The subaerial exposure of the Edwards Limestone (Recharge Zone) contains epigene karst features typical of a karst landscape that contains remnants of relict hypogene processes. Many relict caves in the Edwards Limestone outcrop show evidence of being formed by ascending water. Some appear to be associated with paleo-springs that were abandoned as water levels in the aquifer declined. Evidence of current hypogene processes is found in the saline water zone, which is part of the Artesian Zone. Extremely high permeabilities have been developed by dissolution at depth and driven by a number of processes including artesian hydraulic heads, mixing corrosion, and biogenic acids. As a result, well production in the Artesian Zone is commonly limited only by the size of the pump.


Edwards Aquifer Artesian karst Groundwater Epigene speleogenesis Hypogene speleogenesis 



The authors would like to acknowledge the contributions of Steve Johnson, Dr. E. Calvin Alexander, Dr. Stephen Worthington, and Dr. Alexander Klimchouk in their development of a conceptual understanding of the Edwards Aquifer.


  1. Bögli A (1964) Erosion par mélange des eaux. Int J Speleol 1:61–70CrossRefGoogle Scholar
  2. Dublyansky YV (2014) Hypogene speleogenesis—discussion of definitions. In: Klimchouk A, Sasowsky I, Mylroie J, Engel SA, Engel AS (eds) Hypogene cave morphologies. Selected papers and abstracts of the symposium held February 2 through 7, 2014, San Salvador Island, Bahamas. Karst Waters Institute Special Publication 18. Karst Waters Institute, Leesburg, Virginia, 111 pGoogle Scholar
  3. Ferrill DA, Sims DW, Morris AP, Waiting, DJ, Franklin N (2003) Structural controls on the Edwards Aquifer/Trinity Aquifer interface in the Camp Bullis Quadrangle, Texas, CNWRA, Southwest Research Institute®, San Antonio, TX, 126 pGoogle Scholar
  4. Hovorka SD, Mace RE, Collins EW (1995) Regional distribution of permeability in the Edwards Aquifer. Prepared for Edwards Underground Water District, Bureau of Economic Geology, The University of Texas at Austin, 128 pGoogle Scholar
  5. Hovorka S, Phu T, Nicot JP, Lindley A (2004) Refining the conceptual model for flow in the Edwards Aquifer—characterizing the role of fractures and conduits in the Balcones Fault Zone Segment. Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, 53 pGoogle Scholar
  6. Klimchouk AB (2007) Hypogene speleogenesis: hydrogeological and morphogenetic perspective. Special paper no. 1, National Cave and Karst Research Institute, Carlsbad, NM, 106 pGoogle Scholar
  7. Lindgren RJ, Dutton AR, Hovorka SD, Worthington SRH, Painter S (2004) Conceptualization and simulation of the Edwards Aquifer, San Antonio region, Texas. U.S. Geological survey scientific investigations report 2004–5277, 143 pGoogle Scholar
  8. Palmer AN (2000) Hydrogeologic control of cave patterns. In: Klimchouk A, Ford D, Palmer A, Dreybrodt W (eds) Speleogenesis: evolution of karst aquifers, National Speleological Society, Huntsville (AL), pp 77–90Google Scholar
  9. Rye RO, Back W, Hansaw BB, Rightmire CT, Pearson FJ (1981) The origin and isotopic composition of dissolved sulfide in groundwater from carbonate aquifers, Florida and Texas. Geochim Cosmochim Acta 45(10):1941–1950CrossRefGoogle Scholar
  10. Worthington SRH (2001) Depth of conduit flow in unconfined carbonate aquifers. Geol Soc Am 29(4):335–338Google Scholar
  11. Worthington SRH (2003) Conduits and turbulent flow in the Edwards Aquifer. Worthington groundwater, contract report for Edwards Aquifer Authority, 42 pGoogle Scholar

Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  1. 1.Edwards Aquifer AuthoritySan AntonioUSA

Personalised recommendations