Hydrostratigraphic subdivisions and fault barriers of the Edwards aquifer, south-central Texas, U.S.A.

The karstic Edwards Limestone within the Balcones Fault Zone of south-central Texas forms a productive confined aquifer that consists predominately of dense carbonate rocks and contains several layers of highly permeable and porous honeycombed rocks that have been produced by the leaching of evaporitic, tidal flat or reefal deposits. Fractures have hydraulically interconnected these layers at some places. Faults, however, commonly place rocks of very high-permeability opposite rocks of very low permeability, thus creating a lateral discontinuity and a flow barrier. At places, fault barriers probably cause partial to almost complete blockage of groundwater flow normal to the fault. ?? 1982.