Martinsville Fish Dam - Credit: Wikimedia Commons
The Martinsville Fish Dam is a Native American weir in the Smith River near Martinsville, Virginia. The weir is a rough wall of piled rocks in a V shape with the point of the V downstream. At an opening in that point a basket could be used to catch fish that were funneled to that point by the walls of the weir. Read more on Wikipedia
Source: en.wikipedia.org