Over 7,000 miles of lineations have been observed on aerial photographic mosaics of the Texas Coastal Zone. These lineations, in part, represent the surface traces of faults originating in the Tertiary sediments and propagating through the Quaternary sediments. The extrapolation of subsurface faults from specific oil and gas reservoirs are commonly coincident to lineations in those areas. Some extrapolated fault traces weave back and forth across lineations for 10 to 20 miles and then coincide with another lineation and follow it for 20 miles.

Geologic map that depicts the surface geology of Loving, Crane, and Ward Counties and parts of Ector, Midland, Upton, Pecos, Reeves, Crockett, and Winkler Counties, Texas. The 5-page booklet indicates geologic formations, abbreviations, and ages.

Disposal and temporary surface storage of spent geothermal fluids and surface subsidence and faulting are the major environmental problems that could arise from geopressured geothermal water production. Geopressured geothermal fluids are moderately to highly saline (8,000 to 72,000 parts per million total dissolved solids) and may contain significant amounts of boron (19 to 42 parts per million). Disposal of hot saline geothermal water in subsurface saline aquifers will present the least hazard to the environment.

With the growing concern for finding new sources of energy, there has been renewed interest in an old source, lignite. In the past few years, Texas lignite has been "rediscovered", and a wave of lignite exploration rivals the early oil booms of Texas history. Present heavy leasing activity will be followed during the next decade by the development of numerous mines.

The area described in this report comprises 712 square miles centered on the City of Austin. The area extends north almost to Round Rock, south to the vicinity of Buda, east to just beyond Manor, and west to about 5 miles west of Oak Hill. It includes approximately 604 square miles of Travis County, 38 square miles of Hays County, 18 square miles of Bastrop County, and 52 square miles of Williamson County.