A preliminary study of the Frio sand distribution and formation temperatures and pressures was undertaken in order to define prospective areas in which a more detailed reservoir analysis is necessary prior to the selection of a site for a geothermal well.

Geologic map that depicts the surface geology of Borden, Scurry, Fisher, Martin, Howard, Mitchell, and Nolan Counties and parts of Glasscock, Sterling, Coke, Runnels, Taylor, Jones, Dawson, Martin, Lynn, Garza, Kent, and Stonewall Counties.

Geologic map that depicts the surface geology of Cochran and Hockley Counties and parts of Bailey, Lamb, Yoakum, Terry, Hale, Lubbock, and Lynn Counties.

Lower Cretaceous shallow-water carbonates accumulated on a broad shelf which completely encircled the Gulf of Mexico. Biogenic growth climaxed along the basinward edge, or shelf margin, where a complex of reefs, banks, bars, and islands developed.

Lignite or low-rank coal is a major energy resource in Texas, providing energy since 1850. Prior to 1930, and the advent of abundant natural gas and oil, lignite was a major energy source.

The San Angelo Formation is a mid-Permian sandstone and mudstone sequence about 100 feet thick that crops out in North Texas and dips westward into the Midland Basin; it is composed of two superposed members: the basal Duncan Sandstone Member and the overlying Flowerpot Mudstone Member.

Geologic map that depicts the surface geology of Tom Green, Irion, and Reagan Counties and parts of Midland, Glasscock, Sterling, Coke, Runnels, Concho, Menard, Schleicher, Crockett, and Upton Counties, Texas.

Geologic map that depicts the surface geology of Comal, Bandera, Bexar, and Medina Counties and parts of Real, Kerr, Kendall, Hays, Guadalupe, Wilson, Atascosa, Frio, Zavala, and Uvalde Counties, Texas. The 9-page booklet indicates geologic formations, abbreviations, and ages.

Geologic map that depicts the surface geology of Colorado, Lavaca, and Gonzales Counties, and parts of Hays, Caldwell, Bastrop, Fayette, Austin, Waller, Fort Bend, Wharton, Matagorda, Jackson, Victoria, De Witt, Karnes, Wilson, and Guadalupe Counties, Texas.