I hadn't heard of it before I stumbled upon it on wikipedia, but yeah it's quite fascinating. I've driven through the scablands in Washington, although I didn't know about it/them at the time, was a rather interesting landscape. I'm sure there was a bit of both at varying times but it's hard to imagine a slow release creating those scablands.
Speaking of slow and fast erosion of both the wind and water variety, I've got an old post you might appreciate. It's from a place in New Mexico with slot canyons and hoodoos, all kinds of fun stuff to look at.
RE: A Question Of Water