In this week's Maphead, Ken Jennings explores how a Google Earth discovery lead to a real-life one.
Natural arches are some of the most eye-popping geological formations on earth. Their architectural perfection appears to defy nature; often, they appear to even defy gravity. The national parks of southern Utah get millions of visitors every year to gawk at thousands of natural arches. But until 2009, the most amazing bridge of them all was entirely unknown in the West.
Landscape Arch is the Western Hemisphere champion.
Natural arches typically form where a layer of hard caprock lies on top of a softer stone, like limestone. Wind or water then beats alcoves and cracks in the lower layers of the outcropping, eventually forming a hole below the sturdy caprock—a process that can take millions of years. The arches of Utah are so iconic that the state even put one, Delicate Arch, on its license plate. For decades, locals assumed that the majestic 290-foot Landscape Arch, in Arches National Park's Devil's Garden, was the world's longest arch. Not even close!
Americans spotted Xianren Bridge on Google Earth before real Earth.
In 1988, an aerospace engineer named Jay Wilbur founded NABS, the Natural Arch and Bridge Society, for like-minded enthusiasts. While browsing Google Earth in 2009, Wilbur was shocked at what he found: a rock span over China's Buliu River that no travel guide and no one at NABS had ever heard of, but which appeared to dwarf any of Utah's arches. Locals call it Xian Ren Qiao—"Fairy Bridge"—due to its dramatic and unearthly look.
You almost need wings to visit the fairy bridge.
Xianren Bridge proved difficult for NABS to reach and measure. It's in the rugged karst landscape of southern China about twenty-five miles north of the nearest town, Fengshan. From upstream, it's a three-hour rubber-raft trip to the bridge, with many rapids along the way. From downstream, it's possible to hop aboard bamboo rafts, on which locals will pole you upstream to the bridge. When NABS surveyors finally reached Xianren Bridge in 2010, they measured its span at 400 feet, making it by far the longest arch or bridge on the planet.
London Bridge is falling down.
If you're planning a trip to Fairy Bridge—or any other natural arch—sooner is better than later. All natural arches and bridges are works in progress. Once a hole opens up under caprock, erosion speeds up, and the arch will keep narrowing until it inevitably collapses. London Bridge, a famous double-arch sea stack in Australia, had one if its arches collapse in 1990, stranding two tourists who had to be rescued by police helicopter. Now that it no longer resembles London Bridge, it's just called London Arch. Someday visitors might hike into the Utah desert or southern China and get nothing for their trouble but fallen arches.
