The geological map used is from the "Geologic Atlas of Texas, Sherman Sheet" - Bureau of Economic Geology, 1987. 

Geologic Atlas of Texas - Sherman Sheet descriptive booklet (PDF file - 260k) 

[The best way to print the maps is to save each large image to your computer and then open with the default picture viewer.  This should allow you to print each image and fill a standard 8x11 page without any clipping as may occur if printing from your browser.]