Rock Pile

I decided to stay out of the woods today, and  walk instead  along a 3/4  mile  private drive which
had been cut through a heavily wooded area from the "main" gravel road,  about 50 years ago .
 It provides access to a single lake-side cottage.
Half way along, off to my right,  200 feet into the woods I spotted
this interesting pile of rocks.  It is located on a knoll between two  rocky, spring fed brooks.
In the immediate area there were two other rock piles made up of a single flat boulder with several smaller rocks
placed on top.