Two rock piles in Lancaster, MA

I wanted to explore Lancaster because it is between places "near" home, like Harvard, and places "far" from home, like Leominster. Also Lancaster is reputed to have interesting geology. Unfortunately I chose to explore in a glacial outwash area along Brockleman Rd. and there were very few rocks. It is just too close to the Nashua River. But I saw two rock piles at the highpoint of that road and south of the conservation land.
They were next to a house, right next to a new leaching field and they might have been built to get rid of scrap rock from the leaching field. But they were very nicely built.
And there was some whimsy involved with the placement of one white quartz rock.
I haven't looked at the topo map too much since then but I have to find another part of Lancaster to explore, where there is more exposed bedrock.