The Chinle Formation is of special scenic interest as its beds contain the silicified trees so well shown at Petrified Forest National Monument. These varicolored rocks—red, purple, green, and gray—also decorate the Painted Desert area, the wide valley of Rio San Jose east of Laguna, and flank Interstate 40 (U.S. Highway 66) from the Texas line westward almost to Clines Corners. As some beds are weathered “ash” beds, the highlands were sites of volcanoes that spread their dust over much of the Southwest. In contrast to the underlying marine Paleozoic rocks, these Triassic beds were deposited on land by streams and in shallow lakes. Thus the beasts that roamed New Mexico were amphibians—such as the thick-skulled stegocephalians—and reptiles of the crocodilelike clan, the phytosaurs. The silicified trees in the Chinle are mostly primitive pines; some grew to heights of more than 100 feet and measure 7 feet in diameter. New Mexico was featureless rolling prairie, with scattered low hills in the northwest, during most of Jurassic time (135 to 180 m.y. ago). In the late part of the period, the Sundance-Curtis sea and its shoreline lagoons spread down from the north into northwestern New Mexico. Sand dunes on its southeastern shores consolidated into the cross-bedded Entrada Sandstone; its reddish brown cliffs rim the Rio San Jose Valley near Grants and Gallup. In an extensive lagoon, or salt-water lake that covered most of northwestern and north-central New Mexico, the gypsum and limestone of the Todilto Formation were precipitated; this gypsum is the bed mined near Rosario siding (seen between Albuquerque and Santa Fe) by the Kaiser Gypsum Company, and near San Ysidro on White Mesa by the American Gypsum Company. The Todilto salty basin was overwhelmed by reddish sands and silts of the Summerville Formation, washed chiefly from the south, and by the multicolored sands of the Zuni Sandstone (exposed at El Morro), and then the stream and wind-blown sands and clays of the varicolored Morrison Formation were laid down in northern New Mexico. Petrified wood and bone fragments are abundant in the Morrison beds—along with uranium—but no fossil finds in New Mexico equal those in the Morrison Formation of Dinosaur National Park, Utah. Much of North America, including southern New Mexico, was land during the Jurassic. In the streams and lakes were many kinds of fishes, amphibians, reptiles, snails, crustaceans, and water bugs; on dry land were hordes of reptiles, small primitive mammals, and ants; in the air were flying reptiles, the earliest known birds, moths, and butterflies. The earth was ruled by the reptiles, with the dinosaurs dominant—some being the most ponderous land animals of all earth history. Such were Stegosaurus and Brachiosaurus, the latter 85 feet long and weighing 50 tons.