The entire Colorado Plateau, from Dinosaur National Monument in northwest Colorado to the San Rafael Swell in central Utah and southward to northern Arizona and northwestern New Mexico, might be called a painted desert. Its colorful strata of late Paleozoic and Mesozoic sediments, sculpted into scenic canyons, buttes and mesas by the Colorado River and its tributaries, reflect the bright sunshine of that semiarid landscape.
Officially, however, the Painted Desert is a swath of northeastern Arizona that runs along the eastern edge of the Little Colorado River Valley, northeast and east of Flagstaff. Named for its colorful badlands of the Chinle Formation, this scenic terrain arcs for more than 150 miles, from the eastern edge of the Grand Canyon to the vicinity of Petrified Forest National Park, east of Holbrook. The banded strata of the Painted Desert are composed of siltstones, sandstones and volcanic mudstones (primarily bentonite), deposited in the late Triassic Period (about 210 million years ago) as Pangea began to rift apart; the colors result from hematite and other minerals within the varied layers of sediment. Since their deposition (and especially during the wet climate of the Pleistocene) the Chinle Formation has eroded into a maze of hills and valleys; in some areas, a resistant cap of sandstone protects the soft, underlying sediments, producing buttes and mesas.
Almost all of the Painted Desert lies within the Navaho Nation and large portions have no road access. This fascinating and beautiful landscape is best observed in the vicinity of Cameron (on U.S. 89), from Arizona 87, northeast of Winslow, and at Petrified Forest National Park, east of Holbrook.
