I want to refer you two two items, one older piece by me and another very new, fresh out of the box piece by Carl Zimmer. Not that I'm trying to compare Zimmer and me. But the two posts are somewhat complementary, yet very much on the same page.
How to Date the Grand Canyon: Go With the Flow
Abducted by Aliens ... and dropped off at the Grand Canyon
Well, you've got to admit they are both pretty attractive titles....
More like this
I want to tell you about a great new book that has one forgivable flaw, which I’ll mention at the end. But first, a word from Bizarro Land. This is about the Grand Canyon.
To answer that question briefly, it is really really old if you mean "how old are the oldest rocks that are exposed by the Grand Canyon," and it is probably just a few million years old (5 or 6 by some estimates) if you mean "how long did the canyon itself take to form."
Wait, there's a dam in the Grand Canyon? Why don't we just leave these rivers alone!!!!