Figure 3: Colorado Plateau: Cliff along Highway 550 near San Ysidro, New Mexico. The colorful rock layers are flat-layered Mesozoic Era rocks from the age of dinosaurs. From bottom to top are Triassic Period rocks in the valley, with Jurassic Period sandstone, limestone, and gypsum above. They are topped in some places with Cretaceous Period rocks. Photograph by Jayne C. Aubele, New Mexico Museum of Natural History and Science.