Geologic map that depicts the surface geology of Montague, Cooke, Grayson, Wise, Denton, and Collin Counties and parts of Jack, Fannin, Hunt, and Clay Counties, Texas. The 16-page booklet indicates geologic formations, abbreviations, and ages.

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.

Based on need for convenient, small-scale cartographic units, the basal Cretaceous rocks in Texas from Red River to Burnet County and on the Callahan Divide are herein divided into three distinctive lithologic sequences.

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.

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.

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.

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.