HomeOutdoorsNewsGeologists Revise Age Given to Yosemite Valley by 40 Million Years

Geologists Revise Age Given to Yosemite Valley by 40 Million Years

by Amy Myers
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Photo by Tayfun Coskun/Anadolu Agency via Getty Images

Geologists from the University of California, Berkley, have discovered new evidence that suggests Yosemite Valley is much younger than originally perceived. Instead of 50 million years old, the team of researchers believes the world-renowned valley to be only 5 to 10 million years old.

The geologists behind the new evidence are Kurt Cuffey and David Shuster from the university and Greg Stock from Yosemite. According to the trio, prior to their latest research, there was no concrete evidence supporting the widely-accepted age of the valley.

“Yosemite Valley is one of the most famous topographic features on the planet,” Cuffey, a glaciologist and UC Berkeley professor of geography and of earth and planetary science, told National Parks Traveler. “And of course, if you go to Yosemite Park and read the signage, they will give you numbers for when it became a deep canyon. But up until this project, every single claim about how old this valley is, when it formed a deep canyon, was just based on assumptions and speculation.”

In fact, there’s a great deal of controversy surrounding Yosemite Valley’s age at the park, as well as the forces responsible for carving the entire Sierra Range.

“We know that the Sierra was a high mountain range 100 million years ago, when the granite was forming at depth. It was a chain of volcanoes that might have looked a bit like the Andes Mountains in South America,” Stock, the park’s geologist, said in the university’s press release.

Yosemite Valley Age Determined by Erosion and Uplift

According to Stock, what determines Yosemite Valley’s age is whether the elevation has simply eroded over time or if an uplift occurred. In order to determine the valley’s age, the team of geologists have used Shuster’s recently constructed technique that reconstructs the temperature history of a sample of rock. If the valley truly is 50 million years old, the sample should reveal a long period of cool temperatures.

But the UC – Berkley team found otherwise.

“The temperature history of the rock obtained from the bottom of Tenaya Canyon — from an exposed area of bedrock at the base of Half Dome — indicates that it was more than a kilometer underground 10 million years ago, and most likely only 5 million years ago. This means that a kilometer of rock was eroded away since that time.”

Of course, the team has only scratched the surface of the issue – both figuratively and literally. In the coming years, the geologists hope to gain a better understanding of how erosion and uplift played into the development of the Sierra Range.

In the meantime, they consider these latest findings a geological win.

“The timing of this new study is perfect in the sense that, over the next several years, we’re hoping to completely redo the Geology Hut displays at Glacier Point. I’m very excited to include these new results in those displays,” said Stock.

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