It's not the first time that Flowers has dug up evidence for an older Grand Canyon. In 2008, she authored a study that suggested part of the eastern Grand Canyon, where most tourists go, formed 55 million years ago. Another study published that same year by a different group of researchers put the age of the western section at 17 million years old.
If the Grand Canyon truly existed before dinosaurs became extinct, it would have looked vastly different because the climate back then was more tropical. Dinosaurs that patrolled the American West then included smaller tyrannosaurs, horned and dome-headed dinosaurs and duckbills.
If they peered over the rim, it would not look like "the starkly beautiful desert of today, but an environment with more lush vegetation," said University of Maryland paleontologist Thomas Holtz.
Many scientists find it hard to imagine an ancient Grand Canyon since the oldest gravel and sediment that washed downstream date to about 6 million years ago and there are no signs of older deposits. And while they welcome advanced dating methods to decipher the canyon's age, Karlstrom of the University of New Mexico does not think the latest effort is very accurate.
Karlstrom said it also defies logic that a fully formed canyon would sit unchanged for tens of millions of years without undergoing further erosion.
Geologist Richard Young of the State University of New York at Geneseo said his own work suggests there was a cliff in the place of the ancient Grand Canyon.
Flowers "wants to have a canyon there. I want to have a cliff there. Obviously, one of us can't be right," he said.
Whatever the age, there may be a middle ground, said Utah State University geologist Joel Pederson.
Researchers have long known about older canyons in the region cut by rivers that flow in a different direction than the Colorado River. It's possible that a good portion of the Grand Canyon was chiseled long ago by these smaller rivers and then the Colorado came along and finished the job, he said.
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