Toward the end of the Cretaceous, the Laramide “revolution” began, and New Mexico along with most of North America emerged from beneath the seas, to be high and dry to the present. The revolution, an extensive upheaval of the earth’s crust, saw uplift of the San Juan Mountains area in southwestern Colorado and large volcanoes spouting fire and ashes nearby. Fragments of the eroded mountains and debris from these andesitic volcanoes were flushed southward by streams and steam to settle as thick piles of mud, sandstone, and conglomerate, the McDermott and Animas formations in the San Juan Basin. The last moment of Cretaceous time, if we could be so precise, was ushered out almost unnoticed—with mountains rising to the north and the andesitic-quartz detritus being laid down to the south in the upper beds of the Animas Formation. Similarly, mountains arose during Late Cretaceous time in north-central New Mexico and south-central Colorado, about on the site of the present-day Sangre de Cristo range northeast of Taos, and shed erosional gravels and muds into the Raton Basin area. Alluvial fan gravels and sands grade eastward into dark muds and coals laid down in swamps and on floodplains. These rocks now cap the rugged mesas seen northwest of the Santa Fe Railway from Raton southward—the cliff-forming Trinidad Sandstone and the dark siltstones, sandstones, black shales, and coal beds of the Vermejo and Raton formations. The Kaiser Steel Corporation mine near Koehler extracts coal from these beds. Again, the exact end of the Cretaceous is marked only by some obscure boundary between beds, in that area within the Raton Formation. During the Cretaceous Period, the deciduous trees—such as the oak, maple, poplar, and elm that dominate today’s flora—became common. The covered-seed plants, the angiosperms, are the most notable of the Cretaceous plants, but the development of the modern floras was an antecedent to the great expansion of mammals and birds during the following Cenozoic Era. Reptiles ruled the earth, led by the dinosaurs (fig. 10) and their distinctive group, the horned large-skulled ceratopsians such as Triceratops. The small, hairy, warm-blooded mammals were still insignificant creatures that ran from their huge dinosaur lords, but they ate reptile eggs, and so excelled the sluggish reptiles in mental and physical activity that they adapted swiftly to the changing environments of the Laramide revolution—and became dominant as the pea-brained reptiles were unable to stand the changes.