Hopkinton's Echo Lake and Rocky Woods

...were first shown to me by Bruce MacAleer. My locations on the map (A, B, C below) are vague but I do not think it matters. There are rock pile sites everywhere in this region, so if you try to get to where I indicated, you'll see rock piles one way or another:

I took photos everywhere and we did not see much quartz, nor any good rectangles with hollows - there were a few possibles. I know that at the northern end of this map fragment, at College Rock and south, there are larger rectangular mounds.
The ladies from Harvard and I took 3 separate loops. At A we were walking in along the upper Charles River, following the southern edge. Around A, I saw a little topography off to the side and went to explore:

Nearby:

We headed north, towards A1 and saw a few things in the lowlands:

 SB commented that this had a lot of structure.

And here is some kind of outline:

Beautiful woods.
This might have been a rectangle with a hollow, but built into a wall:

Here is a form we saw several times: the pile next to a gap:

I'll show other pictures later, from B and C.