Paleontology and geology
Geologically speaking, Texas began to form about one billion years ago. Large amounts of coarse to fine sediment were deposited in an adjacent sea. An episode of mountain building buried and metamorphosed these sediments into schists and gneisses, and igneous processes produced magmas that cooled to form granites. By the end of the Precambrian, the mountain system produced by this tectonic event had eroded to near sea level.
Precambrian rocks can be seen today in the area commonly referred to as the Llano Uplift and in the Van Horn and El Paso areas of far west Texas. As the rocks are primarily igneous, fossils are rare to non-existent in the Precambrian rocks of Texas.