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Hells Canyon, the deepest gorge of America, is probably formed about 2.1 million years ago, new studies show. S | Credit: Matthew Morris
Hells Canyon’s origin history, the deepest river gorge of North America, has long been unclear to scientists. But new research estimates that they were formed about 2.1 million years ago, when a dramatic flood probably created a river above the deep gorge.
The researchers made the find after studying clues hidden in the landscape and river deposits preserved in the caves. They described their discoveries in a study published on May 19 in the magazine PnasS
Hells Borders Oregon, Idaho and Washington Canyon. It is cut by the Snake River and is the deepest river gorge in North America, with a width of 10 miles (16 kilometers) and about 1.5 miles (2.4 km) depth -almost 2000 feet deeper than the Grand Canyon.
Canons are inherently difficult to understand and date, the lead author said Matthew MorrisA geologist from Utah’s geological study. “As the river erodes and carved a canyon, it somehow destroys the evidence of its own history,” Morris told Live Science. But since Hells Canyon is so steep, he suggested he was carved quickly.
To understand how the gorge was formed, the team examined the caves on the canyon side. When the floods make the rivers swell, they can deposit a sediment in caves where it is then preserved, Morris said. Researchers analyzed the gravel deposited by the Snake River in three caves along the Hels Canyon sides, and evaluated the age of the deposited material using isotope dates.
This allowed the researchers to determine when the river was higher than its current level, which would be when it formed the canyon. The team combines this information with Knickpoints places – drastic changes in the steepness of the river, where rivers connect to the gorge – to gather the history of Hells Canyon.
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These clues suggest that Hells Canyon was formed when the water diverts from Lake Idaho in the current route of the gorge to form what is now the Snake River. The lake may have spilled due to larger rainfall or changes in the continental division, said Morris. This prompted the river to form a path over the area, which is now Hells Canyon, and the water slowly began to erode the rock about 5 million years ago, after which it carved the gorge much faster than about 2.1 million years ago.
The researchers used the cave sludge to understand how and when Hells Canyon was formed. | Credit: Matthew Morris
The age of the canyon was unexpected. “The age of the canyon was so much the younger than I thought it would be,” Morris said. “I had no idea that it could be 2 million years old – it is a younger than the Grand Canyon, which most people think can be about 5 million years old.”
Hells Canyon has a lot in common with the Grand Canyon, according to Karl CarlstromA geologist at the University of New Mexico, whose work focuses on the Grand Canyon and who did not participate in the new study.
“Grand Canyon and Hels Canyon are always compared to each other,” Carlstrom said. “They are both large canyons with large rivers at the bottom, they are approximately the same length and the same width,” Carlstrom told Live Science, but this study gives a clear picture of the different Hells Canyon history.
“For me, this document is a good hypothesis and he makes the way for next generations of work,” Carlstrom said. Familiarizing more caves in the canyon and integrating other dating methods can refine the findings and make the dates more precise, Carlstrom added.
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The findings may inform the studies of other canyons, which may be carved quickly by rivers, Morris said. Understanding the history of Hells Canyon also gives an idea of how the canyon formation shapes the surrounding ecosystem, as some animal species are separated by the canyon and others connected in it.
Many landscape characteristics of the Southwestern US, such as Hells Canyon and Grand Canyon, are more young than expected before. “[The] The Western United States has a young and ever -changing landscape that has been redesigned over the last few million years and is currently still adapting, “Carlstrom said. This shows how fast – on the scale of geological time – the landscape can change dramatically, he noted.