There was a NOVA program last week about the "Scablands" in Washington. Apparently they're fairly unique geologically - dry waterfalls, areas that look like waves lapping, etc, and 1 guy - don't remember his name - proposed that they had been formed by a large flood of water about 15,000 years ago. He didn't know where the water might have come from.
The scientists of the day said - how could that be, we know the earth was formed millions of years ago in a low process - and basically shut him up for a number of years.
Then, about 10 years later, another scientist discovered some unique geological features in Montana. It looked like there was a glacier there, forming a large body of water, and then the glacier gave way and the water was released, thereby forming the scablands and other unique features.
I fell asleep a little while after, but understand from a friend that the scientists finally decided that this was one of many things that affected the geology over huge amounts of time.
Short and not very good summary, but I thought it was interesting that the bias (can I say that about scientists??) of his colleagues prevented the true information from being recognized for many years.
We may have just a bit of that kind of groupthink going on these days, whatcha think?
Perhaps it is more likely that noone believed him because he had no evidence - you said yourself he couldn't propose where the water came from.
Geologists don't assume that the earth forms by a gradual process only. Gradual is the overall theme, but it incorperates local catastrophic events along the way.
I think you're unaware of the vast mountains of evidence which support evolutionary biology, in dozens of independently cross-confirming ways, and thus all you're left with is imagining that it's just a popular notion that hasn't already been validated and revalidated countless thousands of times.