The Rainbow Bridge National Monument is the world’s largest “natural bridge”, formed by a meandering watercourse.
It is administered by Glen Canyon National Recreation Area, southern Utah, USA. It is often described as the world’s “highest natural bridge. The span of Rainbow Bridge was reported, in 1974, by the Bureau of Reclamation to be 234ft. At the top it is 42ft thick and 33ft wide.
Two other natural arches, KOLOB ARCH and LANDSCAPE ARCH, both also in southern Utah, have confirmed spans several metres longer than Rainbow Bridge, but by most definitions of the terms, they are considered to be “arches” rather than “bridges”. With a height of 20ft, Rainbow Bridge does indeed stand taller than either of its longer competitors, but it is outdone by ALOBA ARCH, in Chad, at 394ft.
The world’s tallest (though less easily accessible) arch is TOSHUK TAGH, better known as SHIPTON’S ARCH, in China at an estimated 1,200ft. Finally, XIANREN BRIDGE (also known as FAIRY BRIDGE) in Guangxi Province in China, with a span of about 295ft and a height of the opening of 210ft, appears to be the natural bridge with the largest span in the world.
Rainbow Bridge is one of the most accessible of the large arches of the world, as it can be reached by a two-hour boat ride on Lake Powell from either of 2 marinas near Page, Arizona, followed by a short mile-walk from the National Park wharf in Bridge Canyon or by hiking, several days, overland from a trailhead on the south side of Lake Powell (obtain a permit from the Navajo Nation in Window Rock, Arizona. Rainbow Bridge is made from sandstone, formed during the end of the TRIASSIC and the JURASSIC periods. Extreme fluctuations in climate, during these periods ———– the region was alternately a “sea” and a “desert” on par with the Sahara Desert ——- produced layers of sandstone with different levels of hardness. By the end of the Jurassic period, the sea returned to cover these layers of sandstone and compressed them so tightly that they persist until the present day. As Bridge Creek flowed toward the growing Colorado River, during the last Ice Age, it carved first through softer rocks and veered away from the harder TRIASSIC & JURASSIC sandstones, eventually creating a wide “hairpin bend” that flowed around a “fin of sandstone” that would become Rainbow Bridge.
The previous course of the creek is still visible above the bridge. Water flows back on itself at bends and wide spots, creating “swirling eddies” along the banks. As the creek flowed around Rainbow Bridge “fin”, these abrasive eddies formed on both upstream and downstream sides, and cut “circular alcoves” in the rock wall. The sediment in the creek eventually scoured the softer layers of sandstone away, leaving the harder layers behind.
Located in the rugged, isolated canyons at the feet of Navajo Mountains, Rainbow Bridge was known for centuries by the Native Americans, who have long held the bridge “sacred”. Ancient Pueblo Peoples were followed much later by Navajo groups who named the bridge NONNEZOSHE or “rainbow turned to stone”. Several Native American families still reside nearby. By the 1800s, Rainbow Bridge was probably seen by wandering trappers, prospectors and cowboys. Not until 1909, though, was its existence publicized to the outside world. Two separate exploration parties ——– one headed by the University of Utah Dean Byron Cummings and another government surveyor, W. B. Douglass, ———— began searching for the “legendary span”. Eventually, they combined efforts. Guides Nasja Begay and Jim Mike led the way, along with the trader and explorer John Wetherill. Late in the afternoon of August 15, coming down, what is now Bridge Canyon, the party saw Rainbow Bridge for the first time.
The next year, on May 11, 1910, US President William Howard Taft used Presidential Proclamation to designate Rainbow Bridge National Monument. Rainbow Bridge became more accessible with the popularity of a river running in Glen Canyon after World War –2, although the trip still required several days floating the Colorado River plus a 7-mile hike up-canyon. By the early 1950s, people could travel upstream by jet boat from Lee’s ferry.
Glen Canyon Dam was authorized in 1956. By 1963, the gates of the dam closed and rising Lake Powell began to engulf the river and its side canyons. Higher water level made motorboat access to Rainbow Bridge much easier, bringing 1000s of visitors.