Rock piles next to boulders

I would not want to assume that these are all the same thing, or that it is easy to tell them apart, but one sees these sorts of piles:After I published examples of rock piles with hollows next to boulders, reader robS sent in some pictures from Maine: Also:I think these are quite a lot like the piles with hollows built against boulders that I reported from northeastern Groton/Horse Hill [here] and previously from the same site. Also these are not too different from the piles reported at Gates Pond in Berlin [here, last two pics] I have already said I think these are a variant of the Wachusett Tradition. Here are some other's I saw on a southern sub-summit of the same Horse Hill. This is a nice one: Another view:Several others from that southern summit of the hill:There were several other rock piles on the sub-summit, and near the top of the main summit, an outline that probably should be noted. The squared blocks make you think this must be a colonial foundation. After seeing all these outlines and hollowed piles, I wonder.