August 11, 2008—In a scene out of a Road Runner cartoon, a soaring sandstone arch has plummeted to the floor of the Utah desert, forever altering an iconic American landscape. But neither Wile E. Coyote nor the Acme Corporation is being fingered for this collapse in Arches National Park.

Erosion—the same force that largely formed the park's arches—and gravity are the most likely culprits for the destruction of Wall Arch sometime last week.

"They all let go after a while," Paul Henderson, the park's chief of interpretation, told the Associated Press.

Wall Arch—shown at top in an undated photo and below on August 5, 2008—was more than three stories tall and spanned 71 feet (22 meters).

Home of the famed Delicate Arch (see photo), the park boasts the world's greatest concentration of natural arches, each the product of millions of years of deposition and scouring.

—Ted Chamberlain