I don’t see how erosional patters are supposed to give any clues about what held back the water. Whether it was a rock wall, ice, a man made concrete dam – the floods that occur when it breaks look pretty much the same and leave pretty much identical erosional patterns.
My theory is different from the ice dam theory in several aspects.
One is the location of the dam failure.
The ice dam theory proposes the dam was located at mouth of the Clark Fork River. All of the water would then be blocked up in Glacial Lake Missoula.
My theory is that the dam was at Wallula Gap. All the water behind the dam was in the Channeled Scablands area.
Here is more supporting evidence of my theory. If we look the erosion area down river from Clark Fork River, it is broad and wide. And it contains many curved erosion patterns. But, after the Wallula Gap, it is much narrower and straighter.
Yet, in the ice dam theory, water had both gone through Clark Fork River and Wallula Gap. However, the erosion pattern is different. If the same amount of water went through both, why the difference?
They formed before any river or flood cut through them, they’re 10+ million years old.
So, are you saying that the topmost layer is 10+ million years old?
This narrow gap caused the waters to back up and a 1,200-foot lake was formed.
Though I quote this, I find it to be a ludicrous answer. A “gap” a mile wide (or even 100 yards wide) was able to form a lake 1,200 foot high? I have some faith, but I don’t have that much faith to believe this.
The only logical scenario I see is that a 1,200 foot high lake could form if there was no gap there at all.