Mystery Rock Piles

A friend sent me this picture of some unusual rock formations. These odd piles of rocks can be found on a river in Kingman, Maine during extreme low water conditions. The erratic rock piles are approximately 2 feet wide at the base and 1-1/2 feet tall and constructed of round stones all around the same size. In a discussion with a local biologist studying local flora and fauna, it was determined they were not made by animals but most likely created by humans.

A web search lead me to a few articles that discuss strange rock formations. However the mystery still remains. Anyone care to propose an additional theory or to hazard a guess? 

• http://rockpiles.blogspot.com/2008/01/mystery-of-monument-mountain-stone-heap.html
• http://www.catfish1.com/forums/f69/rock-piles-altamaha-river-43762.html
• http://outdoors.webshots.com/photo/1401887942043297398lAhvSe