Sunk Meadow - Bolton MA

I saw some rock piles in the woods on the right heading south on Rt 495 after Rt 117. Went to try to find the place and did find a small site but did not see the piles I saw from the road. I parked where I could and walked up along the edge of the highway. After a difficult swamp crossing, I passed a wall and was immediately rewarded with a boulder with a rock pile on it (right (right rear in the picture).
Here is a closer view.
I explored around more and there was a level area beyond with a few rocks and one wedged rock:
This is the wedged rock I video'd here.

As I continued exploring, I came to another boulder with a rock pile, similar to the first one and also next to a stone wall. I realized later that the stone wall next to the first pile goes northwest for fifty yards, turns northeast and goes -say- a hundred yards, arriving at the second boulder and rock pile.
Here is a closer view:
Over to the right of the main pile, there is an anomaly in the stone wall:
Then out beyond this there were a few more rock piles on a knoll and a bit after that I discontinued the exploration.