The Colorado River took the easy route when it carved the Grand Canyon through Arizona's ruddy sandstones and pastel limestones, a new study claims.
Instead of slicing through thousands of feet of unblemished rock, the Colorado River recycled ancient canyons, at least one of which was 70 million years old, researchers reported Sunday (Jan. 26) in the journal Nature Geoscience.
"I think the Colorado River found low places and paleocanyons and ancient topographies that led to the Grand Canyon," said Karl Karlstrom, lead study author and a geologist at the University of New Mexico in Albuquerque.
The new findings, which rely mainly on reinterpretations of other scientists' work, summarize decades of geologic sleuthing. But the study may do little to resolve the heated debate over the age of the Grand Canyon. For the past year, Karlstrom and others have stridently attacked work published Nov. 29, 2012, in the journal Science that suggested the westernmost Grand Canyon was 70 million years old.
But the debate over the Grand Canyon's age has raged for decades, in part because so much of the canyon's history is missing, carried away by the river. The little that's left means many things to many people. The argument also hinges on how one defines the Grand Canyon. Is there a Grand Canyon without the Colorado River running through it? [Video: Virtual Tour of Grand Canyon]
For Karlstrom, the answer is no. Even though his latest findings jibe with the 2012 Science paper, and he reuses that data, he asserts that the Grand Canyon is less than 6 million years old. He was also affronted by claims that dinosaurs walked on the Grand Canyon.
— Becky Oskin, LiveScience
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