Wall Anomoly

This is from Harvard, MA. Sometimes I see things built above the level of the wall and wonder if they are just the remainder of a, once taller, wall or if they are deliberate. In the case of this stack of rocks, I am pretty sure they are deliberate. The structure is solidly built on top of the wall.The lowest rock is a piece of quartz. I also noticed a couple rock-on-rocks downhill from this stack, diagonally downhill in the direction of the dead pine tree and, looking back from them towards the wall, I realized they lined up exactly with this stack. One more view: