PBS is airing a very interesting documentary and I suggest that if you can schedule to watch it or record it, do it. Trust me, you won’t regret it.
The biggest flood in the world and which has geological evidence is the deluge which break through Pacific Northwest every time Glacial Lake Missoula’s ice dam gave way.
This was so huge that it could only be conceived in the minds of the scientists but could not be proved until satellite pictures could be procured.
With the proof in hand now, Geologist are able to point to numerous feature in the landscape that reveal the extreme scale and, literally violence involved in these gigantic floods.
Take a look at these interactive maps from the storied Channeled Scab land and beyond.