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.