The only reason I would have to doubt this is that the world is a terribly destructive place.
The Grand Canyon area is the site of a very old upwelling of mountains, that were then eroded down to sediment, then the sediment was uplifted, and *then* washed down by the Colorado River. The river cut through all that sediment to its base, where it exposed the roots of the ancient mountains.
Now, for those of you who have never seen the Grand Canyon in person, let me assure you, you cannot see the canyon with mere photographs. That thing is enormous. A crack in the world.
Be it a mere six million years, or 17 million years, the big question is, how could this be done here, but nowhere else?
Some comparisons can be made with Copper Canyon in Mexico, Snake River Canyon in Idaho, or the Great Rift of Africa. But they all look a lot more like each other, like “normal” canyons, than the Grand Canyon.
It’s not just size, because parts of the six canyons of Copper Canyon are deeper; and it’s not entirely location, because Snake River Canyon is in a similar situation.
Today, it’s a high desert, but even just 50,000 years ago it was warmer and wetter grasslands. That was when a gigantic meteor hit about 100 miles away, in a 2.5 Megaton blast.
You would think the canyon would have noticed. Apparently not.
I blame the sudden escalation in age of the Grand Canyon on Global Warming.
Without Global Warming, it would have been much younger.
There's more mystery here than the article lets on...