This compilation of potassium-argon (K-Ar) ages of igneous rocks of the Tertiary volcanic field of Trans-Pecos Texas includes all published ages known to us as well as many unpublished results.

The northern Salt Basin in West Texas and New Mexico is a closed hydrologic system in which discharge of ground-water flow occurs in a series of playas, or salt flats.

Changes in shoreline position occurring for more than a century provide estimates of the relative stability of shorelines and, along the Texas coast, allow comparisons of shoreline changes before and after human modifications became significant.

A conceptual hydrogeologic model of the Palo Duro Basin, Texas Panhandle, subdivides the basin into three hydrogeologic units: (1) the shallow Ogallala and Dockum aquifers (Upper aquifer), (2) the Permian evaporite aquitard (Evaporite aquitard), and (3) the deep, confined, underpressured, princip

Near-surface lignite resources in Texas, or those under less than 200 feet (61 m) of cover, are ample to meet the state's demand for lignite in this century.

Oil and gas production in Texas peaked in 1972, but the state still contributed 28 percent of oil production and 33 percent of gas production in the United States in 1984.

In the subsurface and at the outcrop, waters in argillaceous deposits of the Calvert Bluff Formation (lower Eocene, Wilcox Group) are brackish to saline.

Cores from deep stratigraphic test wells provide an excellent basis for determination of source-rock quality and thermal maturity of potential hydrocarbon source rocks in the Palo Duro Basin. Total organic carbon (TOC) content in Pennsylvanian and Wolfcampian rocks is highest in basinal shales.

Topographically controlled ground-water-basin divides, established during the Pleistocene by erosion of the Pecos and Canadian River valleys, prevent ground-water recharge in the outcrop of the Triassic Dockum Group from entering the confined part of the aquifer in the Dockum Group beneath the So

This folded transparent map is at the same scale as its corresponding Geologic Atlas of Texas (GAT) sheet and can be superimposed on it to compare gravity information with surface geology.