Rocks Reveal Jurassic Life

Rocks Reveal Jurassic Life. . , Imagine the Black Mesa as a giant book lying on its side. , Each layer of rock is a different chapter in geologic history. The basalt cap on top is the most recent chapter - it's less than 5 million years old. As you go down, each deeper layer is an older chapter in the story. , Layer by layer, the rocks tell stories of earlier periods in time. , 150 million years ago, this area was a tropical swamp, inhabited by dinosaurs like this Allosaurus. , Rock Layers from Top to Bottom , Raton Basalt (Less than 5 million years old} Sands and gravels of the Pliocene Ogallala group (2 to 5 million years old} Cross-bedded sandstone of the Cretaceous Dakota Group, Gray shale and sandstone of the Cretaceous Purgatoire Formation (92 to 106 million years old) , Exposed on the slopes between the Mesa and North Carizzo Creek (the trail crosses this area): Jurassic Morrison Formation (134 to 150 million years old) Marl and shale of the Jurassic Exeter Sandstone (152 to 57 million years old) Red and buff shale, marl, and conglomerate of the Triassic Dockum Group (215 to 231 million years old) , Dinosaurs Once Roamed this Region , One layer in the book, the Morrison Formation, revealed an amazing story of ancient dinosaur life, including Apatosaurus, Stegosaurus, and the fearsome meat-eater Allosaurus. Approximately 6,000 dinosaur bones were excavated from the 134 to 150 million year-old Jurassic rocks during projects led by one of Oklahoma's most illustrious vertebrate paleontologists, Dr. John Stovall. From 1930 until his death in 1953, Dr. Stovall devoted much of his career to the geology and paleontology of the Cimarron Valley. He was a professor of geology and director of the University of Oklahoma's museum.