Rock Piles in northwestern Willard Brook State Forest and Adjacent - Part 2

With reference to the account and same map here. I continued up the valley of the main brook and kind of got turned around and back where I started and only figured out later that the location was where 'c' is marked on the map - adjacent to one of the open fields up there. At first I saw something suggestive bulging out from a stone wall (yes that's quartz):

A few steps later and something appeared under the hemlocks, something long and thin:

Up closer it was a long rock pile:

There was a hollow on the lower side:

Here is a view from below:

Something like this:

This is a very nice find and it fits with a picture of rock piles with hollows of a slightly different general shape up here in Ashby and (later) southern NH. These northern piles with hollows are longer and more like berms than like mounds. They are not rectangular like the ones further south. For what it is worth this is the Sowhegan watershed while the Falulah mounds are in the upper Nashua watershed.

My plan was to continue uphill and upstream, but I did not see any more rock piles in that direction and an instinct made me stop and remember a basic tactic: never continue from where you find a rock pile without exploring in every direction outward from it. There was quite a lot more to see, back downhill slightly.

A solitary rock pile:

 

Then a huge stone wall-like ruin with too much jumble of structure to get much from.

Here is how it looks up close:

A choice of "hollows", little bits of quartz, and small piles off to the side of the main wall. 

 

Here are 3, evenly spaced.

I have seen these sorts of thing before but these are very beaten down. They seem old.
I thought I was following the main wall but this turned out to be a separate structure: a short stretch of "wall" ending with a space and then a mound with a small hollow. At the other end of the short stretch was a piece of a quartz, the wall turned slightly and continued a few feet.
Here is the wall, the mound is at the far end:

Overall, it looked something like this:

Sorry about the clumsy art. Here is a video: