At the northern end of the Coahuila platform, the thinned Comanchean sequence consists of the newly named Sixshooter group of carbonate formations underlain by the newly named Yearwood formation. The Sixshooter group consists, in descending order, of the Buda limestone, the newly named Boracho limestone composed of the newly named San Martine and Levinson members, and the Finlay limestone at the base.

The Colorado River Industrial Development Association area consists of ten counties [Bastrop, Blanco, Burnet, Colorado, Fayette, Llano, Matagorda, San Saba, Travis, and Wharton counties] in the lower watershed of Colorado River in Texas. The rocks exposed in the upriver part of the area include Precambrian metamorphic and igneous rocks and Paleozoic and Lower Cretaceous sedimentary rocks. In the Austin region Upper Cretaceous sedimentary rocks are exposed. In the downstream part of the area the rocks are of Tertiary and Quaternary ages.

Texas' Hudspeth County talc mining, begun in 1952 when Southwestern Talc Corp. carried out pioneer exploratory operations, has expanded during the last five years and can today claim six active operations. These Include (1) Southwestern Talc Corp., Llano, Texas, (2) West Texas Talc Corp.

The first entry in the Guidebook Series details a field excursion to the Eastern Llano Region of Central Texas in 1958. Retrace the footsteps of Virgil Barnes and the other state geologists in attendance: 

Stop 1. Honeycut Bend

Stop 2. High-calcium reef, Marble Falls area, Burnet County

Stop 3. Granite Mountain, Marble Falls area, Burnet County

Stop 4. Base of Cambrian, Slaughter Gap, Marble Falls area, Burnet County

Stop 5. Texas Construction Material Company...Burnet County

Optional Stop. Mormon Mill locatlity, Burnet County