A site next to Second Brook, off Bush Hill Rd - Hudson NH

I walked down to the edge of the Second Brook (left hand blue rectangle) and found a solitary rock pile there. 

I looked carefully for other piles in one direction, walking 20 yards or so. There were none. I looked carefully in another direction, there were none. There were bushes a few feet away in a dip, and I saw a rock in there. When I pushed through, I could see other piles on a little high spot. I should have known to look on the knoll next to water first. In this case, I am glad I was looking carefully. 
Here are details of the first pile:

This pile is faintly triangular.
And the second pile, in the bushes:

From there I could see another on a little rise (we are looking back towards the brook now):

The little "rise" the little "ridge" [I don't know what to call it] had another rock pile at the other end:

So the piles were in a layout like this with the first pile in the lower left:

These piles are of a type that should be familiar to the reader: smeared out with one white rock. The smear sometimes looks a bit triangular, sometimes a bit rectangular.  Here we are back at the first pile again.