Purgatoire Brook - Westwood MA

I have been dividing my weekend explorations between southern destinations (like Dover and Westwood) and my old favorites - out west in Fitchburg, Leominster, and Sterling. I go south to avoid snow and go west cuz I like it out there. So last weekend found me heading south on 128 towards Westwood and a woods near the Deadham town forest along the -colorfully named- Purgatoire brook.
My successes have been limited lately and this was no exception. I thought I saw rock piles but was not sure if they were ancient or more modern and boring. Later I saw something else and was arguing with myself whether it was natural or ceremonial. The whole notion of finding ceremonial structures is threatened on every side! Joking aside, I think I did find a small site there and it looks like some form of old rectangular mounds, etc.
What was interesting is that sometimes it is the smallest detail that is definitive. I parked at the end of Sandy Valley Rd.and walked back a short ways to look at something on the bank next to the road:

I guess this is the remains of a awfully minimal site:

 Note the shim:

So this direction, west of the road looked good and I continued in that direction, up to a low outcrop and a very messy rock pile:

I could not convince myself this was ceremonial. But it does have those rectangular elements I look for and note the consistent size of its component rocks. Here was a small pile adjacent to the mess:

And a few feet away, another large messy pile:

I was still in a quandry about whether this was not from field clearing. Yes it has ceremonial elements but it is not clear. Then I found this little pile:

To me this is definitively ceremonial. But it is so inconspicuous!
There was more stuff there swinging the jury back in the skeptical direction but, still, that little pile. You see:

Also a bunch of policemen out exercising their dogs. Part of a "CAP" program - whatever that is. Back to the rock piles, here we see something, but...

...it was so formless I could not decide if it was man made.
It was all very ambiguous. Aside from the snow, where are the cairns of yesteryear?