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I'm still trying to understand this part. What makes it (or even implies that it may be) impossible?
Can you explain what actually is "open-and-shut?"

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My question is... why is that impossible? Why can't all those layers form over millions (and even up to a billion... as you say) years before getting cut out? Science that says the earth is old says that the earth is over 3 billion years old. Why can't these layers have been forming for hundreds of millions of years (even close to a billion) and then get cut after they all formed?

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Message 377

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From what I can see... there's only 1 Grand Canyon in the world. It's so spectacular and unique that it's even named one of the seven natural wonders of the world. It doesn't seem like this kind of cutting-through-the-landscape is something that can happen on a regular basis.Something that is so unique on this planet, and only happened once... I don't see much of a problem with that one-time-cutting occurring after "up to a billion years" of layers being formed in the area. After all, those layers had over 3 billion years to form before the canyon was cut. The timeline seems plausible, to me.That is, in all other parts of the world... this sort of cutting has never happened at all for over 3 billion years.
I don't see an issue with it "not occurring for up to a billion years" in just one place on the planet.

Just a general question:Why do all the layers suddenly stop and become a huge mass of granite/schist? (The "Zeraster Granite and Vishnu Schist" area in the diagram below.) I can think of a few reasons, but I'm wondering which one might be correct:

• This area isn't what the diagram is attempting to show, so it's details are not included (like graying out Canada and Mexico when showing a map of the US)
• This is just what happens to any rock-particles that are under such pressure over such a long time... they become granite/schist regardless of what they may have been previously.
• Excavation to this area is difficult, so it's details are not as well known
• Something else?

Just a quick note... this may have happened, but the pooling isn't a necessary requirement (depending on the exact conditions).If the conditions allow for the water to speed up enough to reach equilibrium over the "shallower part" (made shallow by the uplift)... then it's possible for there to be no pooling at all.Or maybe I'm a bit behind... do we know for certain that some pooling actually occurred? If so, then just disregard my comment and I'll be on my way...

In a word... yes. This is basically what happened.Like the picture Percy provided earlier: See how the sides "grow up" around the river in Percy's picture?
Just like that... the walls of the Grand Canyon "grew up" around the river.In regards to sea level... if you stood at the river of the Grand Canyon before and after the uplift... you would be at roughly the same height. It's the walls (rest of the land in the area) that were uplifted.That's why they call it "uplift"... because the land was lifted up.In exact reality... the river may be lightly lower than it was before (with regards to sea-level). But it would be a small change.