Landscape Arch longest in world

Utah state geologists and a group of intrepid volunteers say they've finally answered a nagging question: What's the longest natural arch in the world?

The answer, they say, is Landscape Arch in Arches National Park in southeastern Utah.

Of course, it all depends on how you measure it. But members of the all-volunteer Natural Arch and Bridge Society spent years developing a standardized measurement that looks at the largest horizontal opening in each arch.

Using that yardstick, they found that Landscape Arch spanned about 290 feet. Kolob Arch in Zion National Park came in at 3 feet shorter.

Grant Willis, a geological mapper at the Utah Geological Survey, says the group's survey finally offers definitive answers about the arches with the longest spans.