Paleontology and geologyThe Tertiary in Texas has a rich vertebrate fossil record. Mammalian diversity exploded as new species evolved, filling niches left by the extinction of the dinosaurs. Massive amounts of sediment washed down from the rising Rocky Mountains of the northwest into the Gulf of Mexico. Much of the High Plains and the modern Texas Coastal Plain is covered by rocks (the Ogallala Formation) formed from that sediment. Extensive volcanic activity poured lavas across the landscape in far western Texas. |