A special mound in Shirley

This is the largest berm/mound I know. It continues for while, develops craters, and ends in a stone wall. This is just a few feet south along the trail from the Holden Rd conservation land entrance. The Ft Devens stone wall survey shows this mound as a small "knoll" on the topographic map. Long low berms like this are familiar from northwest of Shirley in southern NH (see Wittmore Hill and Blood Hill posts), but this is the farthest south I have seen such things.

I snapped a picture on the way by, spent most of the walk exploring.