Hat tip to Norman, these are beautiful piles . He says:
Last weekend, at a site in western RI, near the CT line, I was shown a magnificent platform cairn constructed on a flat ledge outcrop. It measured 5m long and 1.2m high, and was roughly oval to circular in shape.
Nearby were cairns on boulders, some fairly carefully constructed, and a possible turtle effigy. In the image shown of the latter, the head is near the bottom, pointing left. Also near the effigy was a boulder with two holes drilled in it. I have seen drilled holes in boulders in Rochester, VT, that make no practical sense, as they are in locations that would be of no help in lifting them.