This particular geological formation is simply one of the more dramatic examples of the effect of a huge quantity of water that couldn't have been created any other way. The world is covered with such examples. The entire world.
Sure, those who refuse to believe what the Bible says about a worldwide Flood some 4500 or so years ago of course make up the explanation that if it looks like it had to be formed by water, then it had to be a local flood. Of course no-one has ever seen a local flood make any such formations as we're talking about. Rivers lay down sediments in layers, and it happens to some extent in oceans too, but all that proves is that water does that sort of thing; no river or ocean ever laid down sediments to the depth or breadth of the layers we see in the formations of the Southwest, or anywhere on earth for that matter.
Take the Grand Canyon. The walls of the Grand Canyon expose the layers of sediments that form the entire plateau into which the Canyon was carved, for many hundreds of miles in all directions. You can see a higher level of layers exposed in the formations to the North, in the Grand Staircase and other formations of Utah, and there is every reason to believe those same higher levels originally extended over the Grand Canyon region as well before they were washed away. The whole stack of layers extends over a huge swath of land now divided by several States of the US.
Absurdly they try to explain this layering in terms of slow accumulation over millions of years. These are neat parallel horizontal layers of different sediments sharply separated from one another, not blurred together but sharply demarcated from one another, a limestone here, a sandstone there and so on, even up to a thickness of 1000 feet in places. Way too neat and separated from one another over hundreds of miles to allow for even a remotely plausible explanation in terms of long ages of time.
No, use your God-given sanctified imagination. There is no way those layers could have formed except by the action of water, and since we're talking about a stack of them that would originally have been at least two miles deep as well as multiplied hundreds of miles in horizontal extent we're talking about a prodigious amount of water, water that would have covered the entire Earth. Just as the Bible says.
And then of course it also took water to cut through that stack of layers to carve out the canyon itself and most of the other odd formations in the Southwest USA, water plus weather erosion. Most likely the water carving was the result of the release of a huge lake that still stood on the earth after the Flood, after the whole stack of layers had been formed, then released as a gigantic cataract. In the case of the Grand Canyon the water probably rushed into a large crack formed in the surface by earthquake activity -- A cross section of the Grand Canyon down to its base rock shows that it is cut into a mound obviously uplifted by an underground volcano, the force of which would have split the upper layers and allowed the release of any standing water into the opening. The rushing water would have sheared the walls of the canyon until it had all run out at the southern end where in fact you can see the accumulation of debris it left in its track on its way to the area that is now Baja California.
A similar scenario must have occurred in the Northwest US where in fact huge standing lakes have been shown by geologists to have existed at one time in the past. Of course they have their timeline wrong, by millions of years. Such a body of water would have been there for some unknown period after the Flood and then released by the breaking of whatever dam type formation held it back, to rush down various canyons where there is now a river still running to the sea. Probably the water would have been released during the compression of the tectonic plates that formed the Rockies, which would also have tilted the land enough in that region to start the water spilling over whatever natural dams existed. [Look up Lake Missoula and Lake Bonneville].
Occasionally you'll read of a search for evidence of Noah's Flood in some specific geologic formation, sometimes in one of the layers deeply buried, a perfectly silly idea. This is to use a microscope to locate a mountain, to study phenomena that are best seen at a distance. Since they can't find the sort of evidence they had in mind they declare the Flood not to have occurred, but BEHOLD! --all over the Earth the evidence is visible to the naked eye. It encompasses ALL of the layers as well as other kinds of formations. The researchers aren't imagining the gigantic scale of such a Flood, the gigantic forces it would have released.
Plenty more to say about this.
