Agrarian use piles from Estabrook Woods, Concord MA

Went walking in Estabrook woods via Punkatasett. Here is a standard field clearing pile, dumped at the edge of a field, made of different sized rocks:
And here is a pile that is all by itself in the woods. Its isolation makes me think it might be a boundary marker:
Oh and by the way, yes there are some real rock piles sites deeper in the woods there.