PBS NewsHour,
Grand Canyon May Be 60 Million Years Older Than Previously Thought:
A newly published study renews an old debate about the age of the Grand Canyon, positing a possibility that the geographical formation could be tens of millions of years older than current wisdom suggests, dating back to the time of dinosaurs. Margaret Warner talks to science correspondent Miles O'Brien about its significance.
An interesting debate has now started over the age of the Grand Canyon, perhaps a paradigm shift?
MARGARET WARNER: Finally tonight: Just how old is the Grand Canyon?
The conventional wisdom holds that this natural wonder of the world was shaped by the Colorado River about five or six million years ago. But there's been a long-running debate over whether it's much older. And, yesterday, researchers published a study in the journal "Science," arguing these majestic formations were formed by two much older rivers cutting through the landscape some 70 million years ago. That was during the age of the dinosaurs.
MILES O’BRIEN: Yes, it's a big deal.
And there is a big debate in the scientific community right now over it, Margaret.
When you look at the Grand Canyon, as a layperson -- we have been there and see it -- you would say, well, clearly, the Colorado River formed this over many millions of years. And we know the Colorado River is between five and six million years old, no scientific debate there. There is plenty of evidence on that.
So, you would say, well, the canyon must be that old. Well, this new paper which came out -- Becky Flowers of the University of Colorado, along with Ken Farley at Caltech, took a series of readings on the eastern and western portions of the river, which measured a helium isotope which stops escaping at about 70 degrees. You can tell how the rocks have been rising out of center of the earth and sort of pinpoint where the depth would be.
And they came to the conclusion that there was a Grand Canyon there some 70 million years ago before the river. Well, how would that be?
Well, they say there were actually two rivers, one that flowed one direction 70 million years ago, another that flowed the other direction 50 million years ago, and that made a canyon, which now the Colorado River is using. Make sense?...
