Best Rockshelter EVAH!

At the apex of a hill on the Chestnut Hill side of the Wissahickon Creek, you can glimpse this collection of boulders, faintly reminiscent of Burnt Hill.
When you reach the summit, the angle of the stones makes their arrangement to be, more likely than not, entirely due to natural processes, although some of the stones may have been modified slightly. In any event, once you find yourself among these stones, you see the following structure immediately adjacent to you:

There is a small platform at the base of the structure and the slope of the valley wall. Noticing this, I walked over to that platform and treated to the following site:

Probably the best cave/rock shelter I've seen along the Wissahickon. It is about 10 feet deep and well sheltered by the overhang pictured above. There is lots of evidence of many fires being built here, blacking of the surrounding stone, etc. The edges of the cave, and the several "layers" of stone visible make it possible that the mouth was progressively enlarged by hand. No evidence that anyone has ever tried to excavate. Immediately next to the main cave, is a small niche in the rock. Another rock has been placed inside the niche, almost like a sort of "shelf". It is heavy enough that I doubt it landed in there by accident.

Also, right next to the cave mouth, there is a lot of evidence of *very* well-worked stone.

Is this natural? Recent? Dunno. On the flat expanse of some of these surfaces, there are some markings.

A snowman?
Maybe someone came along and quarried some of these blocks, but that hypothesis is made problematic in that the sizes and shape of the squared off blocks is irregular, and in some areas just melts into the natural contours of the surrounding stone.