Creationists point to physical evidence of floods occurring all over the Earth as evidence of a global flood. But just as the flood myths and stories simply show floods rather than a single global flood, this physical evidence points to many different floods.
The Grand Canyon is probably the most frequently presented piece of physical “evidence” for a single global flood. An entire book titled Grand Canyon: Monument to Catastrophe by Steve Austin (Inst. for Creation Research, Santee, CA, 1995) is dedicated to arguing that point.
This claim is surely untrue. Simple common sense tells us that.
You can simulate a great flood yourself! The next time that you’re at the beach, fill a bucket with water. Then take the bucket to a place on the beach where the sand is dry. Tip the bucket over. You’ve just simulated a flood.
What do you see?
Many of us have tipped over a bucket of water on a beach either by accident or purposefully and we know quite well what we will see: a wide, relatively shallow flood plane.
There are places that show this pattern. The Scablands in the state of Washington were produced by such a flood and show these features. (The Scablands were created by a large flood caused by an Ice Break, but not a global flood.) The planet Mars has some similar geological characteristics.
But the Grand Canyon doesn’t look like that at all! Instead the Grand Canyon meanders quite a bit and has narrow tributaries as deep as the canyon itself. Those are not the characteristics of a single flood. Other things tell us the same thing.
But the single most compelling argument is this one: if the Grand Canyon is the result of a global flood, why don’t we see similar canyons all over the globe?
 http://www.talkorigins.org/indexcc/CH/CH581.html, referenced on April 23, 2008
 http://en.wikipedia.org/wiki/Channeled_scablands, referenced on April 23, 2008