Grand Canyon as old as the dinosaurs

US: People can be startled at the depth of theGrand Canyon. Now, scientists say dinosaurs may have been, too -- the mighty gouge in the earth is that old.

Scientists have long argued over the age of the multicolored canyon, which is over a mile deep (nearly two kilometers) as many as 18 miles wide (29 kilometers) and 280 miles long (450 kilometers.) Most believe it was carved out about five or six million years ago, based on the age of gravel washed downstream by the ancestral Colorado River.

But new dating methods which harness the radioactive decay of uranium showed it is far, far older, according to a study published Thursday in the journal Science.

"Our research implies that the Grand Canyon was directly carved to within a few hundred meters of its modern depth by about 70 million years ago," said co-author Rebecca Flowers of the University of Colorado Boulder.

AFP