Characterization of 500 of the largest Texas oil reservoirs permits grouping into plays of similar geology and common engineering and production attributes. Most of the major oil reservoirs of Texas are included in 48 plays, which account for 71 percent (32 billion barrels cumulative) of all historical production in Texas. Twenty-seven oil plays lie north and west of the Marathon-Ouachita structural front in Paleozoic reservoirs that are predominantly dolomite and that contained 73 percent of the original oil in place (OOIP) in Texas.

Sand dunes at Monahans Sandhills State Park display a variety of dune forms that develop under a unique trimodal wind regime. Large expanses of unvegetated sand form akle dunes having reversing slip faces. Smaller dune forms in the park include wind-shadow, coppice, transverse, barchan, and parabolic dunes. Blowout dunes also occur in the heavily vegetated cover sands of the Pecos Plain surface. Seasonal wind regimes can be divided into three groups: summer, winter, and spring winds. Persistent summer winds from the south-southeast build long transverse dunes.

A three-dimensional model was constructed of ground-water flow in the Wilcox-Carrizo aquifer system near Oakwood salt dome to facilitate understanding the hydrogeology around salt domes of the Gulf interior region and ultimately to evaluate the hydrologic suitability of Oakwood Dome for storage of high-level nuclear waste. The data base includes not only measurements of hydraulic head and hydraulic conductivity but also lithofacies maps constructed in a previous study of Wilcox depositional systems.

The Chinati Mountains caldera, which lies in Trans-Pecos Texas in the southern Basin and Range Province, was formed by eruption of the Mitchell Mesa Rhyolite. The caldera (30 km by 20 km) is part of a larger Oligocene volcanic province that includes Trans-Pecos Texas and extends to the Sierra Madre Occidental of western Mexico. Volcanism in the Chinati Mountains area began several million years before formation of the Chinati Mountains caldera. Rocks of the Morita Ranch Formation, Infiernito caldera, and Shely Group ring the caldera on the south, east, and north.