Ironically, the Grand Canyon doesn't count because it contains meandering patterns which could not have been formed by vast quantities of water quickly draining off the continent. Nor would soft sediments support the high, vertical walls and pillars found in the Grand Canyon. A good geologist could probably cite many more problems, but I think I've offered enough. Creationists are stuck with an old fashioned flood which covered the high mountains , including Mt. Everest and Mt. Ararat. And, that takes us back to the water source problems mentioned above with a vengeance.
Miracles are the great equalizer.
Any and every theory, from that of the native in the Amazon to the views of the ancient Greeks, are equally good as long as they can use miracles. Thus, in the final analysis, the biblical flood story is no better than the tales of Zeus and of the gods of Olympus. We can't teach that in our science classes. The antediluvian ocean floors then rose relative to the land, causing the displaced water to flood the earth. Large reservoirs of water soon erupted as well, and the catastrophic violence dissolved the surface of the earth.