Force Crag Mine: another fluid dynamics problem

 

I watched the flow carefully through this section at Force Crag Mine.

The water in the middle seems to ride over the top of what is underneath. Then you can see its waves fanning out to the sides, looking a little like diffraction from a point source. I then watched a weak flo backwards along the edges. Inspection of the ramp shows that it is deeper at A so a greater mass of liquid can flow at that point than at the edge B. This explains the V-shaped flow pattern.