How old is the Grand Canyon? The answer you get will depend on who you ask.
Scientists generally agree that the Grand Canyon is about 6 million years old, but they’re more confident about the age of the rock layers exposed by the canyon (which are many millions of years older) than they are of the age of the canyon itself.
Young-Earth creationists obviously reject this story. Since the Earth is only about six to ten thousand years old (according to them), the canyon formed much more recently. Most claim that it is evidence of Noah’s flood scouring out the ground, and they claim that an unbiased reading of the scientific evidence supports such a claim. (See, e.g., here or here for a summary of the scientific evidence that the canyon was recently carved out by a massive flood.)
There’s another group who wants to push the age of the canyon in the other direction, however. Two scientists recently made a study of the amount of helium in rocks as a measure of how long they have been exposed to the surface (according to this article at New Scientist), and concluded that the canyon is in fact far older than previously suspected.
They conclude that the canyon began to be carved out 70 million years old, when dinosaurs still roamed the Earth.
So here we have two challenges to the scientific consensus about the age of the Grand Canyon. Both claim to be the best explanation of the data made available by science?
Are they both equally reasonable? What should we believe?