Old stone rows on Potash Hill - Hudson, MA

A couple of weekends ago we drove past a hill on Rt 62 in Hudson which had what looked like rock piles on it. Last weekend I went back to take a closer look and sure enough there were piles scattered on one part of the slope and adjacent to a loosely defined enclosure of low stone walls. Here are the (respectively) near and far walls of the enlosure.
There were a number of damaged rock piles around and I also saw another loose "wall" going a few yards up the hill:
Nearby on the hill was something a good deal more structured, some terraces:
With a name like Potash Hill, this hill has seen plenty of activity over the last several hundred years and it is hard to imaging a rock pile site persisting there. All the piles are, in fact, in bad shape. Aside from what this implies about the age of the site, with things so badly broken down it is hard to know whether this rock piles site is necessaraily Native American and ceremonial or just the remnants of some activity, possibly practical, that left these structures.