I'm not sure where to ask this question. I suppose it's a fluid dynamics question, a field I don't know well. I saw a show on one of the science channels a while back where it was postulated that huge holes where cut in solid rock beds in the path of a flood which was apparently the volume of one of the great lakes emptying through the area in a matter of days (ice age glacier dam burst). The guy thinks that the vortexes were strong enough to cut the holes (big'uns, seemed like 50 - 100 foot across and deep), in those few days. I'd really like to understand more about this possibility, and what happens in intense vortex situations, and whether they are used this way in any practical applications.