A walk in Mason NH - Boston and Maine Railtrail

A friend from Concord, Carol Montgomery, offered to show me a rock pile site she found in Mason NH; and she took me to a "Rail Trail" heading north from Morse Rd at the southern edge of Mason NH [turned out this was one road west of my furthest west exploration up there].
A few yards in we scrambled up the railroad cut, crossed a wall

and stepped into an extensive area of arranged rocks (at "A"), short stretches of wall, and hollow outlines that are familiar to me from down closer to Fitchburg.

What would this arrangement have been for?

In several places I thought there was a trail passing the structures. For example on the right of the boulders:

Also, there was clearly an old road here:

Since the road went right through here, it suggests the road and piles were "known to each other".

Another bit of old wall [this answers a request by Tim MacSweeney to supplement of the picture ("A picture tells the whole story") from a few days ago. Tim: this is how the wall looked.]

Smaller occasional rock piles grew larger and more frequent as we headed north. Finally we started seeing outcrops with piles built on top of them, and with suggestive "divets" are the edges:

There was much use of quartz:

Just next to this pile was a structure that looked too delicate to last long:

But it had a good coating of lichen and was sturdy. It is just possible this has been in place for a while. Still...more than 100 years? I have a hard time believing it. Many other piles looked completely buried and old. After this we saw many smaller piles with quartz, some with visible "hollow" in the middle. Let's follow along the outcrops, looking at quartz and at piles with hints of structure:

  Look carefully:

Sometimes I think a site may have been selected because it is in a key location with outcrops angling in a useful direction. For example, here much of the site seemed lined up with outcrops or built into them. Other examples: Codman Hill Harvard, and Behind the Horse Farm just northeast of there.

 

One last example of this series was particularly nice:

Look how it continues:

And tapers off delicately:

Then we were into a flat area with beautiful little domed piles, each with quartz, possibly in a grid:

A lovely area:

 Also some piles that were small and hollow:

Isn't that pretty. 

Summary: a site used for a long time. Perhaps for burial and astronomy.