How a massive landslide created the landscape of Zion National Park

May 30, 2016, 6 a.m.
Zion National Park
Photo: Fotos593/Shutterstock

A new study out of University of Utah provides a fresh look at the tumultuous geological history of Zion National Park.

Around 4,800 years ago, the side of a mountain busted apart and brought 10.1 billion cubic feet of rock and debris screaming down at speeds reaching 180 miles per hour, filling the valley floor and damming up Virgin River.

For a sense of scale, "The ancient Zion landslide would cover New York City's Central Park with 275 feet of debris," Jeff Moore, the new study's senior author and an assistant professor of geology and geophysics at the University of Utah, says in a press release. "And you would need 90 times the volume of concrete in Hoover Dam to recreate the mountainside that failed."

The result of this enormous landslide was the formation of a lake that stuck around for some 700 years, and a very flat valley floor, which is now one of the nation's most beloved parks.

Somewhere around 45 percent of the landslide deposit has been eroded away by the Virgin River, and the researchers expect that in another few thousand years, the river will once again return the area to the steep, narrow canyon that it was before the slide occurred.