Twenty-seven geohydrology sections illustrate structural and stratigraphic relationships within the 180-mi-long Edwards aquifer. These sections were used to interpret the location of barriers within the Edwards aquifer. The sections are oriented generally south-southeast, which is approximately normal to both the east-northeast trending Edwards aquifer and the strike of the major faults of the Balcones fault zone. Section lengths represent the distance necessary to cross the aquifer, which is 5 to 40 mi wide. The updip (north) end of the sections are drawn to indicate exposures of the Glen Rose Formation; from there the sections indicate downdip geologic conditions within the freshwater zone and the saline water zone. The sections are approximately parallel and illustrate geologic conditions at 5- to 10-mile intervals. The sections indicate the geologic conditions from near the eastern boundary of the aquifer in Hays County to near the western boundary of the aquifer in Uvalde County. Several sections show places where faults have sufficient vertical displacement to offset the entire, or almost entire, thickness of the aquifer. At these places the faults are barriers to groundwater flow directly downdip across the fault. (Author 's abstract)
