Geologic map that depicts the surface geology of Mills County and parts of Runnels, Coleman, Brown, Comanche, Erath, Hamilton, Coryell, Lampasas, San Saba, McCulloch, Concho, and Menard Counties. The 21-page booklet indicates geologic formations, abbreviations, and ages.

Geologic map that depicts the surface geology of Mason, Llano, and Gillespie Counties and parts of Menard, Kimble, San Saba, McCulloch, Edwards, Real, Kerr, Kendall, Blanco, Hays, Travis, Williamson, and Burnet Counties, Texas.

The Devonian-Mississippian transition outcrops of central Texas are here described summarily and assigned to a new stratigraphic unit, the Houy Formation. The beds included are mainly Upper Devonian, but partly Lower Mississippian. Locally a basal fraction may be Middle Devonian.

Forty-three species belonging to 28 genera, 12 species of brachipods belonging to 8 genera, and 1 species of gastropods are described from the Morgan Creek, Point Peak, and San Saba Members of the Wilberns Formation in the Llano Uplift.

The red upper unit of the Hickory Sandstone is a hematitic and goethitic sandstone containing a large reserve of potential low-grade iron ore.

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 San Saba Member of the Wilberns Formation of central Texas is mostly coarse-grained, trilobitic limestone that grades eastward to dolomite and contains sandstone intervals in its westernmost exposures.