That is a clear flood event. I studied some of the terrain and features on the ground a few decades ago, but to really see them all you have to do is do a fly-over. Pretty clear that a lot of the terrain consists of erosional features.
Agreed. But is there a clear way to distinguish a chaotic flood event like from draining ancient Lake Missoula and the more usual V-shaped valleys from slow erosion?
This was an area overridden by glaciers, and the local flood occurred during their retreat.