Wrentham State Forest - small marker pile site and a lesson learned

This one first caught my eye and then I poked around.Here were a few beaten down piles, perhaps a bit triangular:(Hard to get focused pictures in the rain with a point-and-click camera.)

I did not succeed in photo'ing it, but there were a couple of lines of piles, more or less evenly spaced, scattered along a slope below an outcrop.
After exploring marker pile sites in kettle holes down in Falmouth, I have adopted the hypothesis that marker pile sites are places where shadows are projected from "across the way". I have taken to examining features that are out in the direction that the site faces. So, here I went to take a look and there was a large boulder that would project shadows from a winter sunrise, onto this slope of rock piles. You probably cannot see it but there is a rock-on-rock at the near end of the boulder, next to a slight notch in the rock.