Whipple Hill Lexington, MA - part 2

This shows the Whipple Hill Conservation Land in Lexington. The blue outline is the approximate location of a large rock pile (see part 1).

At a different place in the conservation land was a slope with low oval ground piles. I take it that these are either burials or extremely worn-down marker piles. We were walking along and were descending a slope when I saw this:
I thought it was too in-substantial to count until I noticed it was surrounded by other piles. The whole slope had nine or more piles like this:Now that I look at these more carefully, they look more like marker piles than burials.

An interesting feature was what looked like a more recently built pile - a new pile built up from one of the older ones and incorporating wood to form an enclosure:
The wood might just be from a blow down but it looked as if someone put it there, and not too long ago.