I understand there is a historical and cultural significance to these sites, but I have a sneaky suspicion that maybe the Native Americans (the original permies) made rock piles because of their functionality (thermal inertia, irrigation, etc.) and maybe as an added benefit it was just a nice place to have a ceremony (stacking feature).. just some food for thought. Check out the pictures, the artistry of the the piles is pretty impressive.
Interesting, at least one of those photos is not of a man made structure but rather natural erosion of the bed rock.
My ancestors did stack stones for several reasons 1.to get them out of the way, 2. to reflect the heat of a fire 3. as markers.
In that area there were a lot of little farms back in the 1600's, farmers cleared small fields and stacked the stones either as walls or as corners.
When I lived in Newburgh N.Y. I found many stacks of stones in the three mile wood, these were built by the Revolutionary Army when they camped there.
I also found a perfect stack of cannon balls on the site and several muskets left against trees. Many other artifacts were collected and cataloged.