A couple of comments: First, how do you substantiate that uniformitarian geology has been out of vogue for 100 years? It wasn't until the mid 1950's that J. Harlan Bretz's Missoula flood evidence was accepted because it smacked of catastrophism. It wasn't until about 1980 that catastrophism was generally acknowledged by the geological community. But it is good that it is now acknowledged as a part of the process.
Mt. Saint Helens was mentioned for two reasons. First, it demonstrates that geological processes can happen in very short periods of time. Secondly, during the worldwide flood there was more than just a lot of water. The "fountains of the deep" opened up. There was a lot more going on than just rain coming down, including massive volcanism and tectonic activity. You may disagree with that--I accept that. But I do know the difference between a flood and a volcano.
Also, to answer a previous post. Noah was a preacher of righteousness, and all were invited to come into the Ark. No, it was not God's choice that people perished, but their own.
And yes, there is evidence for a worldwide flood. Many if not most of the sedimentary rock layers were laid down during the flood, and many other geological features are a result of the flood waters rushing off of the rising landmass to the sinking ocean floor.
And I don't think you have given a good explanation of water gaps. Oh yes, the land rose so slowly that the river could continue flowing through the gap rather than going around the barrier. A rather ad hoc explanation.