Grand Canyon’s origin dated to 6 million years ago

Marble Canyon, shown, was carved into the larger Grand Canyon in the last 6 million years. It was the linking of smaller canyons like this one roughly 5 to 6 million years ago that formed the grand chasm similar to what is seen today, new rock-dating data suggest.

 

Laura Crossey/Univ. of New Mexico

The age of the Grand Canyon has been strongly debated among geologists, with some estimating it formed up to 70 million years ago. New results from a rock-dating method, however, support the more traditional view that the Colorado River cut the canyon into its grand form more recently.

The rock-dating method measures when erosion brought deeper rocks to the Earth’s surface. One segment clocked in at 50 to 70 million years old and another at 15 to 25 million years old. But two segments were much younger, carved only 5 to 6 million years ago, researchers report January 26 in Nature Geoscience.

Even though parts of the canyon are much older, the chasm could not have taken on its grand form until erosion from the Colorado River connected all of the smaller canyons — which was roughly 6 million years ago, the scientists argue. 

photo of Ashley Yeager

Ashley Yeager is the associate news editor at Science News. She has worked at The Scientist, the Simons Foundation, Duke University and the W.M. Keck Observatory, and was the web producer for Science News from 2013 to 2015. She has a bachelor’s degree in journalism from the University of Tennessee, Knoxville, and a master’s degree in science writing from MIT.

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