What are kolks in megafloods?

[Mk]

I was looking at NOVA's Megafloods page, and was fascinated at the kolks that formed weird humungous potholes. No Wikipedia article, and unexpectedly harder to find information on Google. What do you know about it?

 

[matthyaouw]

Google seems to have very little information. From what little I have read, it seems to me that they are little more than eddies and currents like you'd find in normal rivers, just on a much larger scale.
I can't really find anything that doesn't make reference to catastrophic flooding/glacial dam failure. Studying such rare and high magnitude events is nearly impossible, so I doubt there would be much literature on them.

 

[Andre]

Have you tried Lake Missoula floods or Lake Agassiz floods?