Sixteen depositional sequences, commonly called cyclothems, each composed mostly of limestone(retrogradational/transgressive) and siliciclastic (progradational/regressive) subsequences, or systems tracts, record the paleogeography during Late Pennsylvanian (Virgilian Epoch) and Early Permian (Wol

The Ogallala aquifer, which underlies the Southern High Plains, consists of the saturated sediments of the Neogene Ogallala Formation. The aquifer is the main source of water for the High Plains of Texas and New Mexico and is being severely depleted by extensive pumpage for irrigation.

This cross section set comprises 14 dip (E-W) sections and 9 strike (N-S) stratigraphic cross sections (with text), correlating upper Pennsylvanian (Virgilian) and lower Permian (Wolfcampian) strata throughout the subsurface in all or parts of 28 counties of North-Central Texas.

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.

The Upper Triassic Dockum Group of Texas and New Mexico is composed of 200 to 2,000 feet of complexly interrelated terrigenous clastic facies ranging from mudstone to conglomerate.

Nelson and others (1962) define a bank as " ... a skeletal deposit formed by organisms which do not have the ecologic potential to erect a rigid wave-resistant structure." They explain that a bank may have any geometry.

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.

The Eastern Shelf was a constructional platform developed on the margin of the sediment-starved Midland Basin during Late Pennsylvanian and Early Permian time. A mixed terrigenous-carbonate sedimentary province characterized the shelf during most of its history.

Lower Cretaceous sands have long been important aquifers in Central, North-Central, and North Texas. In recent years these sands also have been sources of high-silica industrial or specialty-purpose sand.

These are 21 Texas county maps made in cooperation with the American Association of Petroleum Geologists and Society of Economic Paleontologists and Mineralogists, issued between 1929 and 1932 and revised in 1937.