Another marker pile site in Westford

I might as well tell you where this one is, I don't see the harm. This is the Tom Paul trail heading east from Graniteville Rd within the first quarter mile you cross a brook on an inconspicuous stone bridge and the a medium sized site develops to your right on the rocky knoll. There is evidence of boulder quarrying up here and after that a rock pile site. Let me repeat that: parts of the site were built after the quarrying. I know this because the perched rock here has itself been quarried.
This site had a bit of everything: split-wedged rocks, propped boulders, lines of marker piles, and even a horse-shoe mound (shown earlier today). At this site the marker piles were of the type with a pointed rock sticking up or hanging off the edge.
The piles occur on a slope, in lines and with the characteristics we described for a marker pile site.

Here is the main gift this site gave me: I followed a line of piles down the slope to a ledge. And there in the ledge was a prominent piece of white quartz. The quartz was at the end of the line of piles. This is somehow very consistent with what we saw on the earlier hilltop in Westford - lines of piles with quartz implicated. But here the implication is more direct: the quartz is at the end of the line.
You can follow this in the three pictures starting from the top, viewing through the "V" formed by two small trees, to the ledge near the bottom.

I have seen this before, notably at another famous marker pile site down the valley aways in Harvard - see Manitou p. 279.