New rock piles on Great Hill in Acton, MA

I went for a very pleasant walk with my wife Barbara at Great Hill in Acton. This is the big hill along Rt 27, pretty much behind the "Discovery Museum". It is a conservation land that I have visited a number of times in the past, finding small clusters of rock piles in three or four places. But I was trying to come up with someplace near home to explore and had been day dreaming about exploring around the northern part of this hill - a part of the hill I'd never been to.

We parked at the little parking lot on Rt 27 at the foot of the hill and I planned to cut to the left and head for the northern side of the hill. But when we got out of the car, I said: let's take a moment to look at the hillside, I just want to look closely. Here was the view:Looking carefully, it seemed that there might be some rock piles on the slope. In fact there were several suspicious "shadows on the rock" - where rocks might be piled up a bit.[ Click on the picture to see more detail.] It seemed the slope might actually be covered with rock piles. Who knew! How many times have I been past here without noticing anything? I have gotten better at knowing what to look for, or maybe this is the first time here without tree leaves blocking the view? So we went up the slope and, yes, it is covered with 50 or so rock piles. This is very typical type of site for a westward facing, steep, hillside that is flat or concave: all the piles are visible at one time, seen from various places on the slope. Let's take a closer look. The light was not good, so pictures are a bit blurred.The piles are damaged but the layout is still reasonably clear. In many places you could see lines of piles, evenly spaced:I asked my wife to stand with a pile at her feet, to help show the line:There is a lot of damaged structure up here but you still can get a decent sense of the place.
Evidently a major calendrical site. No question that these are ceremonial rock piles:Little question that the piles along with almost every rock were part of the large scale deliberate layout.Near the top of the slope, some larger boulders with rock piles, or damaged remains of rock piles: As we moved across the slope, heading towards the north side of the hill, I said to my wife that there might be some further clusters of piles. We went around a slight shoulder of the hill and did find a separate cluster of piles. I pointed out that, as we went around this shoulder of the hill, the first concave section was no longer visible. Now, with new sight lines, there was another cluster of piles. This is what I expected because I believe the use of these sites involved looking along lines of sight over, or along the sides of, these rocks and piles. Nice old piles in the dead leaves.