Rock piles along a stone wall in Stow, MA

I was on my way back from an disappointing excursion to Sudbury State Forest and saw a piece of woods in southern Stow that looked like a nice piece of woods with water and rock. Passing a small conservation land sign I realized I could go in. When I stepped into the woods there was a lot of slashed logging debris underfoot. [Time constraints prevent me from ranting about this horrible forestry practice of chopping down most of the trees and leaving lots of branches and stumps on the ground. This can turn acres of nice woodland into a place which is impossible to walk through and will remain that way until some forest fire cleans it out. Whole sections of Mt Wachusett are destroyed for hiking this way]. So I picked my way carefully along the hillside, not really expecting to find rock piles. But when I got all the way across the conservation land to a wall, I saw a rock pile a few feet from the wall.
It was in bad shape and I did not think it was significant, probably just part of the wall. I followed the wall along and found a second similar pile - on the ground, not too well defined - about the same distance from the wall. So I was thinking - perhaps these were part of the wall building, or that perhaps someone had dumped piles along the side of the wall. But then I saw this wedged rock on the other side of the wall and, to me, this is distinctly ceremonial:
Look more carefully at the wedge - certainly an eye catching crystal inclusion.
There were some other features on the far side of the wall including more rock piles along the wall (some pretty decrepit), some little standing stones, some faint traces of alignments:
(Look closely along the vertical line above the small rock pile in the foreground - there are four rocks, one in the distance - not a very good alignment).

There was a a nicely formed oval ground pile:(closer)(closer)I was looking to find white quartz in the pile and, instead, saw a black rock. Now you know I think of quartz and ground piles as indicating possible burials. So what is this? A different kind of burial or something different?

Also along the wall there were other very decrepit items, looking like rocks dumped along the side of the wall. I was vacillating between believing and not believing this was a ceremonial site. That wedged rock is pretty compelling but...still. There were maybe 10 or so piles along this first stretch of wall I explored. There were many piles so covered with debris, so subtle. Who would ever even notice them?
Then I walked uphill and into a corner of the walls maybe 30 yards from the first cluster of piles. Here there was a puddle of water trapped in the corner and another collection of piles. These were much less ambiguous, and here was the quartz (a closer view of the same pile):
(closer)
But these piles were also evenly spaced and somewhat in lines - which I imagine as different from burials - using the phrase "marker piles".

I was thinking more about marker piles being evenly spaced. Say you asked someone to draw 20 dots on a piece of paper, keeping the dots as evenly spaced as possible and within a confined part of the page. People will either place dots in triangles or rectangles to do it. A kind of "grid" appearance emerges even if that is not the intention. Anyway, this was more ambiguity for the site. Piles along a wall, mostly the same distance from the wall, some even spacing, some quartz, some black burnt rocks, give the site its particular character.

The corner of the walls was itself an interesting place with a well constructed "corner cairn":Here are a couple of panoramas showing the wall corner. First the view from the rock piles (the corner cairn is just to the right)There are about eight evenly spaced piles along the near side of the water. They are pretty invisible. Here is a view back towards the site on the other side of the water. A very typical and lovely spot for a rock pile site.
After poking around a bit more I headed back to my car.

I saw a big rock-on-rock (just beyond the puddle to the right in the previous picture)As it turned out there were more rock piles all the way back to within maybe 20 yards of my car. Had I turned uphill at the start of the walk, I would have been in the rock piles the whole time. These last piles, forming a somewhat distinct cluster along a different wall ,were also ground piles. I noticed one with an unusual concentration of lighter (feldspar) rocks:I noticed a couple that were larger and more above ground:
These are really small mounds, with a lot of below surface volume. They may be more than 10 feet across. So they are substantial but - geez! - they are invisible. Who will notice them? Luckily they are protected in this conservation land.The neighbors are probably not aware of this site, maybe thirty or more rock piles across the street.