Ted’s most recent posting about similar damage to oval stone piles, reminded me of a large platform cairn in Brooklyn, CT, that I saw a number of years ago. It is one of the largest platform cairns I’ve ever encountered. Only one end is well preserved,the other sides are notI don’t think that blowdowns can account for the damage, since the pile is so huge (about 45’ long and 7’ high) and well constructed, at least on the preserved end. Nor does vandalism seem a good explanation. I could be that stones from the pile were used to construct walls and foundations – certainly a logical source. [I would call that "vandalism" - PWAX] And once stones began to be removed, the structural integrity of the mound was compromised and it began to collapse of its own accord.
Norman continues in another email:
This stone mound was in a dilapidated condition before the tree fell on it, and because it is stone’s throw from some old colonial foundations, I concluded that the farmers took stones from the mound to build foundations for a barn and house. To see what little effect a large tree will have on a well built stone mound, here is an example from S. Newfane, VTI would add this example: the large platform at Miller's Hill in Holliston, MA (see here):
I felt, when looking at it, that rocks must have been pulled from the bottom of the retaining wall and, as Norman said, the pile would collapse sooner or later after that.
Another small example here.