A Large Enclosure

Last weekend's kayak outing was rained out.  Since the Thunderbird Nest enclosure was mentioned on  the Rockpiles blog, I think I'll show my photos of a large enclosure.  These were taken in May of last year, somewhere in MA near the site of a praying Indian village.
     I was walking along an old road on a Saturday afternoon.  This road was abandoned after a major highway was built nearby  in the 1950s, and it is amazing how  the forest reclaims vacant areas.  Once school kids crossed here.

As I was walking, I looked uphill and saw the following.  Large rocks litter the slope, and at  the top  stands a low "wall" of smaller stones.

The view looking downhill from the top of the slope.

The center of the pile has a large cavity.

Here's another view. The enclosure is about  eight feet across, and is visible at the top of the rocky slope in satellite imagery. That looks like a propped boulder directly  uphill, near the top of the frame.

  So what is this?  The size and shape are similar to that of the Thunderbird Nest, so maybe this was a place for vision quests.  Ot it could be a sweat lodge base, or a fort built by kids from the nearby school.  I hope  when I go back in the fall, I'll find more structures and get a better idea.