Editing Natural arch (section)

==Water-eroded arches==
[[File:Coyote Natural Bridge map.jpg|thumb|A [[topographic map]] of Coyote Natural Bridge in Utah shows how the [[meander]]ing [[Coyote Gulch]] carved a shorter route through the rock under the arch. The old riverbed is now higher than the present water level.]]
Some natural bridges may look like arches, but they form in the path of streams that wear away and penetrate the rock. Pothole arches form by chemical weathering as water collects in natural depressions and eventually cuts through to the layer below.

[[Natural Bridges National Monument]] in Utah protects the area surrounding three large natural bridges, all of which were formed by streams running through canyons, the largest of which is named [[Sipapu Bridge]] with a span of {{convert|225|ft|m|sp=us}}. The [[Rainbow Bridge National Monument]]'s namesake was also formed by flowing water which created the largest known natural bridge in the [[Western Hemisphere]] with a span of {{convert|234|ft|m}}, based on a laser measurement made in 2007. [[Xianren Bridge]], also known as Fairy Bridge, in [[Guangxi]], China is currently the world's largest known natural bridge with a span recorded at {{convert|400|ft|m|sp=us}} by the ''Natural Arch and Bridge Society'' in October 2010, with a precision of ±{{convert|15|ft|m|sp=us}}.<ref>Jett, Stephen C.[http://www.naturalarches.org/china/journal.html#fairybridge China Diary] {{webarchive|url=https://web.archive.org/web/20131229025325/http://www.naturalarches.org/china/journal.html |date=December 29, 2013 }}, The Natural Arch and Bridge Society</ref><ref>{{cite web|url=http://www.naturalarches.org/big-FairyBridgeMeasurement.htm|title=Big 17 Tour - Measurement of Fairy Bridge|website=www.naturalarches.org|url-status=live|archive-url=https://web.archive.org/web/20131112172533/http://www.naturalarches.org/big-FairyBridgeMeasurement.htm|archive-date=November 12, 2013}}</ref>