South of Tucumcari, rising boldly from the red-earth lowlands draining to the Canadian River, are Tucumcari Mountain and Mesa Redonda, and to the northwest the long buff cliffs of Mesa Rica. The latter mesa lies north of Interstate 40 as far west as Newkirk. Patches of the white caprock caliche-limestone cap these eastern New Mexico sentinels, whereas in other localities, the brown Dakota Sandstone tops the buttes and is underlain by pink Jurassic sandstones, with the mesa bases made up of the Triassic redbeds. Near Santa Rosa, Interstate 40 dips down into the narrow green valley of Rio Pecos. Roadcuts lining the steep hills into the city show the red and brown sandstones and shales of the Triassic beds. Driving westward from Santa Rosa, one crosses rolling hills near Clines Corners, then dips gently down into the northern part of the Estancia Basin near Moriarty. To the north on the horizon are the snow-capped peaks of the Sangre de Cristo Mountains. From Moriarty, Interstate 40 pulls slowly upward toward Edgewood into the eastern foothills of the Sandia Mountains, the grassy plains giving way to juniper and piñon groves. From the downgrade into Tijeras Canyon, State Highway 10 leads north to San Antonito and the turnoff to Sandia Crest. The crest road winds up canyon walls, on sloping limestone mesas, up through thick stands of ponderosa pine, aspen, and, near the top, Engelmann spruce and corkbark fir. Rocky Mountain bighorn sheep may be seen off the road on the high crags. From Sandia Crest, 10,678 feet above sea level, much of north-central New Mexico is visible; Mount Taylor to the west, the Nacimiento and Jemez mountains to the northwest, the mighty Sangre de Cristo Mountains to the northeast, and countless ranges to the south and southwest. The city of Albuquerque is spread out at the base of the Sandias, and the twisting north-south channel of the Rio Grande stretches, glistening, as far left and right as one can see. From Tijeras, Interstate 40 plunges into Tijeras Canyon, slicing through vertical roadcuts in Pennsylvanian limestones and shales, then through the ancient Precambrian granite. At the canyons mouth, the road levels off on the broad alluvial plain on which much of east Albuquerque is built, although the “downtown” is really down, in the valley of the Rio Grande. Westward, Interstate 40 rolls up out of the valley, crosses windswept plains spotted with black volcanic cones, in and out of the shallow brown valley of Rio Puerco, and then to the red-cliff-bordered valley of Rio San Jose. Cliffs are of brown, buff, and light-gray Jurassic sandstones, with the valley carved in Triassic redbeds. Near Laguna, on the north side of the valley, white gypsum of the Todilto Formation crops out. Then through the pink Jurassic cliffs the canyon winds, and near New Laguna, the highway is bordered by the varicolored, uranium-bearing Morrison beds, which are overlain by brown sandstones and black shales of Cretaceous age.