"uniformatarianism"?

That sounds sort of like some kind of orthodox religion. :-) And it might just be.

Is it the idea that all such changes must necessarily be gradual and occur only in small increments over a very long time?

If so, it is an idea that will always appear rock solid and dependable right up until something happens that isn't gradual...after which all bets are off, and people may be too busy for awhile just surviving to even bother about theories.

But my own hope is that you are correct, and we manage to dodge any major catastrophic event while we are living out the rest of our lives here.