Natural Bridges National Monument is a U.S. National Monument located about 50 miles (80 km) north west of the Four Corners boundary of southeast Utah
, in the western United States, at the junction of White Canyon and Armstrong Canyon, part of the Colorado River drainage. It features the second largest natural bridge in the world,carved from the white Permian sandstone of the Cedar Mesa
Formation that gives White Canyon its name.
The three bridges in the park are named Kachina, Owachomo, and Sipapu (the largest), which are all Hopi names. A natural bridge is formed through erosion by water flowing in the stream bed of the canyon. During periods of flash floods, particularly, the stream undercuts the walls of rock that separate the meanders (or "goosenecks") of the stream, until the rock wall within the meander is undercut and the meander is cut off; the new stream bed then flows underneath the bridge. Eventually, as erosion and gravity enlarge the bridge's opening, the bridge collapses under its own weight. There is evidence of at least two collapsed natural bridges within the Monument.
The Monument's elevation ranges from 5,500 to 6,500 feet (1,700 to 2,000 m). The Monument's vegetation is predominantly pinyon-juniper forest, with grass and shrubs (brittle brush, Mormon tea, sage, etc.) typical of high-elevation Utah desert. In the canyons, where there is more water and seasonal streams, riparian desert plants, such as willow, oak and cottonwood trees, thrive.
The main attractions are the natural bridges, accessible from the Bridge View Drive, which winds along the park and goes by all three bridges, and by hiking trails leading down to the bases of the bridges. There is also a campground and picnic areas within the park. Electricity in the park comes entirely from a large solar array near the visitors center.
In 2007, the International Dark-Sky Association named Natural Bridges the first International Dark-Sky Park, which is a designation that recognizes not only that the park has some of the darkest and clearest skies in all of the United States, but also that the park has made every effort to conserve the natural dark as a resource worthy of protection.To date, Natural Bridges has the only night sky monitored by the NPS Night Sky Team that rates a Class 2 on the Bortle Dark-Sky Scale, giving it the darkest sky ever assessed.