More Franklin State Forest

[Referring to the previous post] After leaving the small decrepit mounds behind, I headed east back towards the road I came in on (which leads from Metcalf Rd to the summit of Forge Hill) and saw outcrops, stone walls, and a large "foundation hole" I ignored on the way in. This can't be more than a hundred yards from the road, adjacent to those swamps.

A nearby wall coming down from the ridge with the road:

Any ideas about what that is?
Then I did come to larger mounds with hollows (if that is what you call this kind of damaged structure) built on the outcrops:

 

These mounds are in the higher land southeast of the swamps, between the swamps and the road leading up to the summit.