The Grand Canyon, a breath-taking marvel on the landscape of North America, has been a centre of attention among the scientific community for its mysterious geological history.
In a recent breakthrough, the scientists are now uncovering the precise timeline of how the Colorado River first began its craving of the region.
To reconstruct the river’s history, researchers analysed microscopic clues buried within the canyon’s layers. The clues consist of resilient mineral crystals named as Zircon grains made up of sediments carried by the river and particles of ash ‌ from volcanic eruptions long ago.
“Scientists ​have long debated when the Grand Canyon was carved, and our study contributes to that conversation,” said UCLA geologist John He, co-lead author of the study.
As per findings published in the journal Science, the river’s evolution began roughly 6.6 million years ago when it began to flow to a large depression, called a basin, in the Earth surface, leading to the formation of a wide and shallow lake in the east of future the Grand Canyon.
As the lake’s volume increased, it eventually crested a low point on the shore about 5.6 million years ago.
This overflow sent a powerful surge of water carving through the landscape, effectively starting the formation of the Grand Canyon, the researchers discovered.
The river’s journey continued as it filled and spilled through a succession of basins from the Grand Canyon. Eventually it reached the Gulf of California about 4.8 million years ago and emptied itself into the sea.
But the lake named as Bisahochi Lake which was formed at the spot of the Grand Canyon has long disappeared.
“A longstanding question has been: where did the Colorado River go before it flowed through the Grand Canyon?” said study co-lead author Ryan Crow, a research geologist at the U.S. Geological Survey in Flagstaff, Arizona.
“We have long known that the river existed in western Colorado 11 million years ago, and that it did not (run through) the Grand Canyon until after 5.6 million years ago. But until now we knew almost nothing about where it was during the intervening time,” Crow said.
