Ancient Landslide Had Final Say in Zion National Park’s Genesis

'Zion Canyon wall'

Utah researchers believe that the Zion National Park owes its existence to a monster landslide.

A team of researchers from the University of Utah found that a huge landslide might have helped shape the state’s iconic national park and its breathtaking canyon about 4,800 years ago.

The new study is a continuation of a 1945 research paper that has first advanced the idea that a huge landslide might have shaped the park’s striking landscape. But that older study had failed to fully understand how that was possible.

Jeff Moore, lead author of the 2016 paper and geophysics researcher at the University of Utah, recalled in a recent interview how he felt when he stumbled upon the older study. He said that the idea of a landslide helping shape the park was like a lightning bolt strike.

Over the years, the researcher worked to develop the idea and make the public aware of the little-known possibility. A few years ago, Moore’s team started analyzing the geological features and composition of the Sentinel Mountain.

Their research comprised three separated stages. First, scientists estimated the size and speed of the ancient landslide. Second, the team took surface rock samples and measured the levels of beryllium-10, which is a radioactive isotope that can help geologists determine the age of rock samples. And finally, the team compiled all these data in a computer model.

The model estimated that the landslide was immense. It displaced 10.1 billion cubic feet of soil at speeds of up to 200 mph. The team believes that the event was so quick that it took about a minute to reshape the entire landscape.

Analysis of beryllium-10 helped researchers determine the approximate age of the event. They believe that the rock avalanche happened about 4,800 years ago. Study authors think that the event was so huge that if it happens again today it would displace enough land to hide the NYC’s Central Park under a 275 foot-thick pile of debris

Researchers also believe that the landslide helped create a natural dam around the Virgin River which resulted in a lake which lasted for nearly a millennium. The Virgin River still crosses Utah’s Zion canyon to this date.

Because of the ancient lake, evidence pointing to the 4,800-years-old landslide remained “hidden in plain sight.” One piece of evidence is the canyon’s floor which is now covered by the sediments deposited by the river.

Moore believes that thousands of years ago the entire canyon was filled with a lake.

“It’s a wonderful thing to imagine,”

Prof. Moore said.

Image Source: Wikimedia

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