Eastern Slopes of Ballard Hill - Lancaster MA

The last several weeks my strategy for choosing a place to go exploring has been limited by two things: a desire to not drive very far; and a desire to explore headwaters of brooks feeding the Nashua River (or any large waterway). Since I have already explored most of the places less than a 1/2 hour drive away, this strategy has me scraping the bottom of the bucket. But having a "headwaters" theory gives me a new focus and I've been doing pretty well. I had a couple of "misses" but more often than not I am still finding new things. To make a long story short, it worked at Ballard Hill.
[see also:
Mason NH had piles at headwaters (although I was there for other reasons).
Horse Hill had piles at headwaters (I wrote about the path from the water to the hill.
The Throne had piles at headwaters (I used this strategy).
The east side of Ballard Hill had 1 nice mound at a headwater. (I used this strategy).
We'll see that on revisiting Rattlesnake Hill (in Bolton) there were piles at the headwaters there too.
It is not just that there a piles at these places but specific types of piles, which I listed, particularly rectangular mounds with hollows but also short stretches of stone wall and outline features on the ground. As an alternative to rectangular mounds with hollows it might be piles built against boulders or outcrops, with hollows.]

Usually I would stay a long way from Lancaster. It always disappoints. Ballard Hill looks like a possibility but, years ago, I gave it a quick once over and saw lots of laurel but almost no rocks on the surface. So you have to imagine I am getting desperate if I am willing to give the place another try.

The Nashua River is on the right, and you can see the brook. It has no name. The woods were dull as expected but one place I came to a low wall in the swamp. Lines likes this are a common feature at these sites (Mason for example).

Note the quartz at the near end. A few steps later I saw a cove with sloping sides and a vernal pond at the bottom. "How many times have I seen things down along the sides of coves like that?" I thought, and a few more steps and my feet found the mound. I would not have seen if I was not standing on it.
Here it is from the side:

Here from below:

Here from the other side:

Here from above:

From thirty feet away:

That's it. The pleasure is all the greater for having found this in a place where there isn't anything. The next day I saw some nice things in Bolton but that's like shooting fish in a barrel.