I have no idea at what elevation the ark landed, only that the mountains were covered, so if a mountain was 13,000 feet high then the water was 13,000 feet deep. The mountains could well have been 8,000 feet high prior to seismic activity after the flood, but the point made is that they were covered by water, regardless of elevation. The flood was global. It killed all land creatures not on the ark. Presumably the intent was to get off the boat, so it would make sense that it would rest fairly high up in the mountains instead of in a valley somewhere.
You missed my point, in that, since you don't know where, or at what elevation, the Ark came to rest, you cannot use your evidence for a global flood. Consider the flooding of the Black Sea, which is one of the more likely candidates for what became known as the Biblical Flood: it has a maximum depth of about 7200 feet, so something that began at the bottom of that basin before it was flooded would rise up into the surrounding mountains as the water from the Mediterranean poured in. Large water level rise, and yet still a local flood.
Yes it does. I had to go back and check my sources, since I read the explanation I based my post on several years ago. The question it seems is not the existence of the delta but the magnitude. Even given that most of it has eroded since the dams were built, it still doesn't account for the magnitude of material that must have been removed. Neither does gradual erosion account for sheer vertical walls, which would have to be cut by a tremendous flow of water over a short period of time.
1) As you said, the delta has been sediment-starved for about 80 years now due to the dams. You'd be surprised at what wave action can do in 80 years.
2) Before being dammed, the Colorado delta covered ~7800 square kilometers. In comparison, the Mississippi delta covers 12,000 square km. That's not all that big of a difference, especially considering the differences in water quantity and drainage area between the two rivers.
3) I don't know which Grand Canyon you visited, but the walls really can't be called sheer and vertical. Portions are, but the canyon itself is up to 18 miles wide (and only a little more than a mile deep). The steep sections are simply due to the weathering characteristics of the rocks.
4) Geologically, 17 million years (about what it took to cut the Grand Canyon) is a short time, but I've never heard anyone who doesn't work with deep time say that.
