All the bridges in Natural Bridges N. M. were carved from the Permian Cedar Mesa Sandstone, also the star in Canyonlands N. P. In Canyon de Chelly (pronounced “dee shay”) N. M. and Monument Valley (neither N. P. nor N. M., as it is owned and administered by the Navajo Tribe), the de Chelly Sandstone Member of the Cutler Formation—a Permian member younger than the Cedar Mesa—plays the starring role.
Wupatki N. M., near Flagstaff, Ariz., stars the Triassic Moenkopi Formation. Petrified Forest N. P. (which now includes part of the Painted Desert) also has but one star—the Triassic Chinle Formation, with its many petrified logs and stumps of ancient trees. The Triassic-Jurassic Glen Canyon Group ([fig. 9]), which includes the Triassic Wingate Sandstone and Kayenta Formation and the Triassic-Jurassic Navajo Sandstone, receives top billing in recently enlarged Capitol Reef N. P., but the Triassic Moenkopi and Chinle Formations enjoy supporting roles.
The Triassic-Jurassic Navajo Sandstone, erosional remnants of which are found on the high mesas of Canyonlands N. P., is the undisputed star of Zion N. P., Rainbow Bridge N. M., and Glen Canyon National Recreation Area, despite the fact that the latter is the type locality of the entire Glen Canyon Group ([fig. 9]). The Navajo also forms the impressive reef at the eastern edge of the beautiful San Rafael Swell (a dome, or closed anticline, [fig. 7]), now crossed by Highway I-70 between Green River and Fremont Junction, Utah.
As we journey upward in the time spiral ([fig. 80]), we come to the Jurassic Entrada Sandstone, which stars in Arches N. P., with help from the underlying Navajo Sandstone and a supporting cast of both older and younger rocks. The Entrada also forms the grotesque erosional forms called “hoodoos and goblins” in Goblin Valley State Park, north of Hanksville, Utah.
Moving ever upward in the spiral, we come to the Cretaceous—the age of the starring Mesaverde Group, whose caves in Mesa Verde N. P. now house beautifully preserved ruins once occupied by the Anasazi, the same ancient people who once dwelt in Canyonlands N. P.
This brings us up to the Tertiary Period, during the early part of which the pink limestones and shales of the Paleocene and Eocene Wasatch Formation were laid down in inland basins. Beautifully sculptured cliffs, pinnacles, and caves of the Wasatch star in Bryce Canyon N. P. and nearby Cedar Breaks N. M. This concludes our climb up the time spiral, except for Quaternary volcanoes and some older volcanic features at Sunset Crater N. M., near Flagstaff, Ariz.
Thus, one way or another, many geologic units that formed during the last couple of billion years have performed on the stage of the Colorado Plateau and, hamlike, still lurk in the wings eagerly awaiting your applause to recall them to the footlights. Don’t let them down—visit and enjoy the national parks and monuments of the Plateau, for they probably are the greatest collection of scenic wonderlands in the world.
Additional Reading
