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

Approximately 2,200 ft (670 m) of principally continental and paralic rocks of late Virgilian, Wolfcampian, and early Leonardian age (late Pennsylvanian and early Permian) are exposed in an area of about 4,950 mi2 (12,800 km2) between the Brazos and Red Rivers in North-Central Texas.

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.

Geologic map that depicts the surface geology of Hardeman, Wilbarger, Wichita, Clay, Knox, Baylor, Archer, Haskell, Throckmorton, Young, and Foard Counties and part of Jack County, Texas. The 20-page booklet indicates geologic formations, abbreviations, and ages.

The Fort Worth Basin, in North-Central Texas, is a late Paleozoic foreland basin that was downwarped during the Early to Middle Pennsylvanian Period in response to tectonic stresses that also produced the Ouachita Thrust Belt.

The Canyon Group (Missourian Series) is a sequence of westward-dipping, genetically related carbonate and terrigenous clastic facies that crop out in a northeast-southwest belt across North-Central Texas.

A mineral resource survey of Texas, started by the Works Progress Administration, is still being conducted by the Works Projects Administration, with the Bureau of Economic Geology of The University of Texas acting as the sponsor.

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.