Here is another "roadside attraction", which I photo'd on my way back from exploring on Sunday. It is in the Skinner parking lot, next to a picnic table. The Skinner driveway is on Rt 117 in Bolton not too far east of Rt 495.
In fact this large boulder is propped up on a broken piece of rock.
According to geologists, these large propped erratics were left here by the retreating glacier. It would be interesting to hear what scenario they would concoct to explain how a broken - sharp edged rock (obviously untouched by the glacier) got under there.Aside from that, common sense suggests that it would not be too hard to lever this thing around a bit.
I guess I should also point out that this large boulder is not so obviously a glacial erratic.