Grand Canyon as old as the dinosaurs: study

Grand Canyon as old as the dinosaurs: study

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.

Researchers believe the canyon was likely carved at different times and paces.

Flowers and her colleagues has previously shown that parts of the eastern section of the Grand Canyon likely developed about 55 million years ago and have subsequently eroded much further.

This latest study examines mineral grains from the bottom of the western part of the canyon.

"An ancient Grand Canyon has important implications for understanding the evolution of landscapes, topography, hydrology and tectonics in the western US and in mountain belts more generally," Flowers said in a statement.

mso/dw