This photo shows a boulder about six feet in diameter that was eroded from the walls of the stream valley. The surface facing us was once on the bottom of the stream. You can see at least five circular depressions about one foot in diameter and six to eight inches deep on the surface facing us. They were formed by eddies of swirling water. These "potholes" are a product of stream erosion by abrasion. Some examples of potholes in the process of formation may be seen in the stream bottom above the waterfalls.