For the last nine years I have been reporting on rock pile sites where the rock piles lie in lines and are more-or-less evenly spaced along those lines. As someone who has looked at more than 300 rock pile sites I can add that these types of rock pile sites are not just abundant but are actually the most common sites to be found, especially the further south I go exploring from here in Concord. I have also speculated about how these sites are calendrical. The most convincing evidence is the hypothesis confirmation as shown for example here.
Last weekend I found two sites with rock pile lines on the slopes of a knoll. At both sites the rock piles lay all to one side of the high point. At one site there was a brook nearby with some other rock piles there; at the other there was a short stretch of stone wall leading up to the high point. So the sites had their differences. Rock piles in lines often are constructed with one good near-vertical face while the rest of the pile tapers off with less structure. So when I see piles like that, and see a high point, and sense the piles being in lines, I am sure I am looking at an example of the same kind of very specific rock site function. Saturday I saw one site like this in Bolton. Sunday I saw another in Framingham. Let's have a look.