Hopkinton State Park - Between the Picnic Areas

I am afraid I have forgotten who told me about this site. It's a beauty.

Inside the loop road:

Also check out outside the loop road, to the west:

 Nice stack, in the background.

These are classic examples of what I call "marker piles". They are evenly spaced, more or less in a grid. Vertical sided. I assume they had a calendrical function because of the explicit, site-wide, geometric properties. "Marker" because they are like tic marks on a 3D ruler.