The Grand Canyon, a breathtaking wonder on the landscape of North America, has been the center of attention among the scientific community for its mysterious geological history.
In a recent breakthrough, scientists are now tracing the exact timeline of how the Colorado River first began its way to the region.
To reconstruct the history of the river, researchers analyzed microscopic clues buried within the layers of the valley. Clues include flexible mineral crystals, called zircon grains, made up of sediment carried by rivers and ash particles from volcanic eruptions.
“Scientists have long debated when the Grand Canyon was formed, and our study contributes to that conversation,” said UCLA geologist John Hay, co-lead author of the study.
According to the findings published in the journal Science, the river began to develop about 6.6 million years ago, when it began flowing into a large depression in the Earth’s surface, called a basin, creating a wide and shallow lake east of the future Grand Canyon.
As the lake increased in volume, it eventually reached a low point at the shore about 5.6 million years ago.
Researchers discovered that this overflow sent a powerful wave of water across the landscape, effectively starting the formation of the Grand Canyon.
The river’s journey continued as it continued to fill and expand through the Grand Canyon into the canyons. Eventually it reached the Gulf of California about 4.8 million years ago and sank into the ocean.
But the lake named Bisahochi Lake, built in place of the Grand Canyon, has disappeared long ago.
“An old question is: Where did the Colorado River go before it flowed through the Grand Canyon?” said study co-lead author Ryan Crowe, a research geologist at the U.S. Geological Survey in Flagstaff, Arizona.
Crowe said, “We have long known that the river existed in western Colorado 11 million years ago, and that it did not flow through the Grand Canyon until 5.6 million years ago. But until now we knew almost nothing about where it was in the intervening time.”
