With respect to part 1 here and part 2 here. Another site in Leominster:
...I was pushing my way through light undergrowth and came to a curve of three rock-on-rocks:
and looking back:and then a pile:and I thought to myself: oh goody! something irregular.
There you have it:A classic quadrant 3 hollow - by which I mean an outline seen from overhead like this:
Let me be clear, the three rock-on-rocks led to the pile with the hollow.
Downhill from it a smaller pile, then some ski-jumps:And within about 1/2 acre there were several outlying piles:At the bottom of the site, a stone wall with this entrance. To me this suggests the site was in use, or contemporary with the time, when the wall was built. And now looking upwards towards the ski-jumps:I hope you agree there is some basis of comparison between these sites with "central mound" arrangements. Also some similarity with the rock piles with tails we have looked at. Also, compare with Hopkinton State Forest. Some common themes.
Update: Also consider the site north of Oak Knoll Dr. in Upton. (Warren Brook)
See also here