The scene is set. According to Indian legend, when the Great Creator made the earth and had finished placing the stars in the sky, the birds in the air, and the fish in the sea, there was a large pile of rejected stony materials left over.

Texas is no longer a frontier. The expansion of cities, industries, superhighways, and reservoirs, and changing land uses are fast absorbing the open spaces that once were so abundant in Texas.

This report is a compilation of all available data on mineral resources (exclusive of oil and gas) in 39 south Texas counties. Information from published and unpublished sources was checked and supplemented by field investigations.

Tertiary rocks, including sandstone, conglomerate, shale, pyroclastics, tuff, and lava, are preserved in Big Bend National Park and in a much larger area to the west and northwest. Some of the rocks have distinctive characteristics that enable recognition by their lithology.