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.

Geologic map that depicts the surface geology of parts of Presidio, Brewster, and Terrell Counties, Texas. The 14-page booklet indicates geologic formations, abbreviations, and ages.

Geologic map that depicts surface geology of parts of Hudspeth, Culberson, Jeff Davis, and Presidio Counties, Texas. The 12-page explanatory booklet indicates geologic formations, abbreviations, and ages.

This Guidebook represents an updating of Bureau of Economic Geology Guidebook No. 5, Field Excursion-Geology of Llano Region and Austin Area. It also represents a modification of Geology of the Llano Region and Austin Area, Texas, published by the Shreveport Geological Society in 1971.

The departure point of the Villa Capri Motor Hotel may be gone, but the geologic information within Guidebook Number 3 remains relevant to this day:  "The four stops of this field trip are in the Upper Eocene (Jackson) and Oligocene volcanic ash and bentonite beds, which crop out about

Vermiculite deposits in the Central Mineral region of Texas, chiefly in Precambrian metamorphic rocks, are situated in Llano County and adjacent parts of Mason, Gillespie, and Burnet counties with minor occurrences in Blanco and San Saba counties.