A small rock pile site in Callahan State Forest - Framingham MA

Not far to the south of the Wayside Inn and southwest of Nobscott Hill there are other hills, in Callahan State Forest. During the window of opportunity provided by the good weather two weekends ago, I explored a small part of this Forest and did actually find a small site and a thing or two of interest.

This small site is just west of Nixon Rd. in the woods. As I was walking, I came up first to an outcrop with a little bit of rock piling:
And then what I thought was an isolated rock pile:
But there was also another pile behind it, hidden in the saplings - a kind of elongated pile:Another view:
Also a bit further, this split filled rock (also filled with forest debris).
These are distinct types of pile but not in an aggregate that I recognize. These are not features of something familiar. I think there are more woods to explore over there.