Many rivers on the US East Coast have weirs in the sense of a device for catching fish. They are v-shaped lines of rocks, with the point of the V downstream, and they tend to divert larger fish through an opening at the point. I learned many years ago that those on the Rappahanock between Remington and Fredericksburg were built by "native Americans" long before the great invasion.

It's interesting that they have survived all these years through centuries of flooding and wars. It's also interesting that almost invariably the point of the V is in the center of the river. If I were building one I'd put that opening closer to one shore or the other. Perhaps there were enough people living on both sides of the rivers that putting the opening in the center worked best for all concerned. Or perhaps there's a physical reason why those with the point in the center survived over the years.


TEd