Oak Hill - between Rt 2 and Old Schoolhouse Rd

Oak Hill, on the eastern side of Harvard and southern Littleton, is the major land form in this valley of Beaver Brook, Elizabeth Brook, and the Boxborough esker made famous by Mavor and Dix.

I have explored around Black Pond several times and there are nice rock pile sites in the lower lands at the foot of the main hill. I thought I would go again and, with a new understanding of a "Wachusett" culture, look more in the uplands, and see what was to be seen. The sites lower down do not have large rectangular mounds with hollows (that I could see). Are they related? So I parked at A, in the usual place, and walked diagonally uphill over to B which was the first location where I could access the road that runs along the ridge (Old Littleton Rd). From there I walked down the road to its junction with Old Schoolhouse Rd and managed to sneak back into the woods near C. It was one of those walks where I spent more time thinking about trespassing than about the rocks and woods. Anyway, at C I found a nice Wachusett Mound just at the brow of the hill looking eastward:

 

At first I doubted this was more than just a field clearing pile. There were some larger boulders strewn around carelessly nearby and I was arguing with myself that the component rocks of the pile (eg in the last picture above) were too regular sized for field clearing. But then I looked over the edge. The pile is built on top of an outcrop and I could see some little pieces of construction at the foot of the outcrop:

I could see the main pile from below and tried to get it into the picture. When I got home and looked at this carefully, I conclude there is another rock pile here, between the outcrop and a separate boulder. There are also little bits of stone wall and a damaged enclosure of larger slabs, something a bit like this:

You can see much of this in the two pictures. In the end, I don't think this is field clearing. Also there were some little details:

Like the small pile in the foreground. 

So far, I see no obvious connection between this and the small piles at the sites below. I have found another large mound situated in exactly the same way on Oak Hill but a quarter mile south of here.