The Grand Canyon is nowhere near the grand old age of 70 million years that earlier studies claimed, according to new research. "The Colorado River found a path and carved the entire canyon 5 (million) to 6 million years ago," says a geologist who used data measuring the cooling of rocks with time. But while the canyon as we know it may be relatively new, the river recycled portions of old canyons, at least one of which is indeed 70 million years old, LiveScience finds.
"If you were to add up the 280-mile length and ask, 'how much is young? More than half of it is young; a quarter of it is middle-aged—15 (million) to 25 million years old; and the rest of it is 70 million years old," the lead researcher explains to the BBC. "It continues to deepen today, of course. Right now, over the course of the last half-a-million-years or so, it's been deepening by about the thickness of a piece of paper every year." (Read more Grand Canyon stories.)