Edges and transitions exist in rivers too. Coming from the West: wetlands, otters, and water so clear that a simple glance will clean your retina. Moving to the south east: floodplain forest, white-tail deer, and brown turbid coffee water.
Paul resting atop a giant rock hill deposited by ancient glaciers ~10,000 years ago. In the background is the last stretch of wild rice we have seen. Transition.
This video shows the dammed reservoir at Grand Rapids which marks a major transition on the Mississippi River. The dam was used for hydropower and milling during the early 1900s.
Having fun with it,
3.1 lbs trash packed out of the river