Hopping Brook in Holliston - part two

Continuing from here. I went to a lower "Hopping Brook Rd 2", parked again and walked in past a sandpit to an entrance to the woods.

Again I was drawn to the left and upward (upper blue outline):

I spotted a rock pile beyond the wall:

Going over there, I entered an area of many small rock piles:

They continued up the hillside:

 

 Some with vertical sides:

 Some in a line, evenly spaced:

This is called a "marker pile" site. It partakes of the ruler, grid, and calendar. The component rocks are large:

And it seemed the higher on the hill, the taller the piles. Perhaps they were to be viewed from below.

Some artistic experiments: