Approaching a larger rock pile site

I had been climbing up the hill and not seeing much - happened on a trail that led one direction down a long slow boring slope, so I went the other way on the trail, following a stone wall. I saw a solitary rock-on-rock over on the other side of the wall and was happy to take at least one picture:
And I looked around a little bit more and saw a couple of low decrepit rock piles:
(A detail in this rock pile, a bit of lighter colored feldspar with quartz on it, centered in the pile)Looking further, another pile:
And then some other small things, but now the structures are beginning to seem related the one to another:And then some slightly more substantial but still badly damaged rock piles:
And I was struck by how many of the piles seemed to incorporate one larger rock. In the last picture of a split-filled rock, the 4th rock in is slightly pointed and sticking upward. These sorts of things - piles with single larger rocks and piles in relation to one another - begin to suggest a familiar pattern.

And some pretty things, in the beginning of fall colors:
And then I thought: "Well that is about it, nothing else to see. As an after thought: but I really should just check up hill from here...."