On the way to the Archaeology Walk in Cedar Swamp

I took a wrong turn and it was getting late but when I reversed the mistake and headed back in the correct direction, I spotted some dappled light and shadows underneath rocks. What the heck, I parked and took some pictures:

 There seemed to be smaller and messier things, closer to the road:

Another view, a pretty typical rectangular mound with a hollow:

Again:

In this view, look at the embrasure on the right:

I hurried back to my car and ended by arriving just as the walk was beginning. It turned out to be a spectacular place, the bit of land jutting into the swamp to the right of the 'H' of Westborough. The light was gorgeous under the yellow leaves of early fall.

The talk itself was "intro to archaeology". We stood in two places in the woods and listened to the speaker read from cards. At the second place, on the only hill around in the swamp, GC and I spotted a bit of stone wall and headed over to investigate. On one side of the stone wall was a large, recently constructed fireplace. On the other side was a circle of stones scattered around, which I interpret as where a rock pile got destroyed to provide rocks for the fireplace. It is natural to wonder about the alignment of the wall.
The 'mound' is about where the cross hair is on the map, adjacent to the Gravel Pit.