Geology of the Permian Basin, West Texas Area. Precambrian rocks underlie Texas, which are more than 600 million years old. The deformed ancient volcanic and intrusive igneous rocks and sedimentary rocks were formed early in the Earth's history. They are now exposed in the Llano Uplift and in a few small areas in Trans-Pecos Texas. 6-pages, bibliography lists 5 sources. Pages: 6 Bibliography: 5 source(s) listed Filename: 12938 Geology Permian Basin.doc Price: 53.70