Continuining to walk clockwise around Sandy Pond

Walking clockwise on the north side of Sandy Pond, Lincoln the account left off here:

Continuing as the trail nears the northern end of a little wetland, on the  right is a small rectangular  horseshoe-shaped pile.

Hard to photo:

It wasn't until we got around to the northeast side of Sandy Pond, along the edges of that wetland, that more extensive mounds started to show up. This gives you an idea:

This whole side of the wetland has a "debris" of stones piles along it.  I have seen very similar things at Woodbridge Rd in Carlisle. This was more extensive.
I am looking over the photos, trying to decide what to post. How about this:

I am pretty sure that is what a pile looks like when it has been deconstructed. It's what a vandalized pile looks like. But actually, there were so many other things:

View back up towards the path:

These are long mounds with hollows. Sometimes it seemed an extended complex, sometimes a collection of separated features. Here the view is to the west or northwest:

Let's take another look at that first example:

Again:

It is almost a spiral.
Here some little "chambers" going along the same wetland edge:

It is clear these are deliberate structures.