Circular Ditch-and-Mound in the land of Nashoba

 [Dan Boudillion writes:]

Do you recall the earthen circles Mavor-Dix reported at the Boxborough esker?

I found something like that a few miles away using Lidar and confirmed it on the ground. 

 

For refence, here are the esker circles on Lidar:

And here is what I noticed on Lidar a few miles away:

These are in a heavily wooded area, in a swale.  They are about 30 feet across, and constructed but digging a shallow circular ditch and piling the dirt in the middle. They are lined up exactly to magnetic north. 

 

I don’t have pictures because it was not possible to capture the structures with a camera due to forestation, size, and shallowness of the ditches.  In fact, had I not been looking for them and GPS-ed the exact location, I would not have seen them even if I walked over them, they are that subtle on the ground.

 

Anyway, any thoughts on these?  I don’t know what they are, either here, or at the esker. 

[Peter writes:]

Apparently circular mound/ditch features have been discussed before on this blog:

Rock Piles: Re-reading Dan Boudillion about the Boxborough Esker and Circular-Ditch-and-Mound

I think the Dunstable example is north of Frederick's Corner.