Seventeen Million Years Old. Deal With It

How old is the Grand Canyon? One answer is easy: a lot older than a few thousand years. A more precise answer is harder to get at, however. You have to climb into the caves of the Grand Canyon and read the geological clocks hidden there. For more, read my latest "Dissection" commentary at Wired.

Photo: Luca Galluzi at Galuzzi.it [via Wikipedia]