Blood Rd - Groton, MA

From what started as a run down little site I spotted from the car (here), to some "crescents" in the snow (here), to a village of small mounds with hollows (here), this site has proven to be larger than expected until, now, it is found to fill a valley more than a mile and a half long.

Small rectangular rock piles with hollows, some occasional "sentinel" rock piles sticking up high above the surrounding smeared out mounds, and (what we'll see today) rock piles built against boulders but with vestiges of hollows - all these features make the site a somewhat unique manifestation of the "Wachusett Tradition". This site is a northern variant, with piles down by the water,like the rock piles "with tails", and different from the larger mounds one finds 20 miles further south, which are larger and located high on hill slopes.

I went back to explore further north in this valley between Blood Rd and Horse Hill. I was following a dirt road "Dan Parker Road" and cut off to the east at the high point, and immediately came to a split boulder that was butterflied into two vertical faces, connected to a very smeared out mound with a hollow:It takes some deliberate imagining to see this as a variant of a mound with a hollow. But what else could it be? Here is a closeup of the split boulder: Here is the "hollow":
Adding: By "butterflied" I mean the boulder was split and (apparently) opened up so the flat surface of both pieces face outward in the same direction.

To be clearer, here are some other examples of rock piles built up against boulders. You can decide whether they might have been burials once upon a time.
Meanwhile, here are some more conventional rectangular piles with hollows. In these examples there is often a hint of a 2nd hollow - which I think is one form of the "tail" we see on some rock piles.
Especially on this one:I'll show some other features I spotted in another post.

Meanwhile, outside of the blue outline on the map fragment, there is a bit more of this valley still to explore and probably more to see.