Monday, October 22, 2007

Nashoba Hill - Westford, MA

A few days ago I was contrite that I missed knowing about the rock piles on Nashoba Hill - the ski place. So FFC got permission from the landowner and we explored the western part of the hill as thoroughly as possible. There might have been "ca'rns" up there twenty years ago but the only signs of any today are one solitary rock pile at the southern extremity of the wooded slope (1/4 way down), a rock-on-rock with a classic "boat rudder" shape:
and a few boulders surrounded by cobbles suggesting piles that had been cast down.

Otherwise, the western side of the hill is covered with subtle little 4-in-a-row or 5-in-a-row lines of low rocks. FFC is so fond of looking up the directions with a compass and trying to interpret them with the "Stupid Sheet" [see link to the right] that it was hard to make progress combing back and forth across the slope (at different height levels on the hill). But we did eventually give the hill a pretty good going over and, not seeing any great show of "ca'rns", it is less embarrassing to have missed what was there. I had also been told about some piles at the edge of the swamp east of the hill. So the day after exploring the hilltop, I went and looked over there along the swamp. Eventually, and not that close to the hill, I spotted four low ground piles, which I will show you later. But they were so inconspicuous I have a hard time believing they would be "ca'rns" so described. So I think I need to explore some more.

There is one long continuous stone wall that runs across the summit of Nashoba Hill from northwest to south-east. This wall has been measured over and over and Tim Fohl's observation that the wall is aligned with the summer solstice sunset and winter solstice sunrise seems to be correct. West of the wall is woods, east of it is the ski area. Here is the solitary pile from along the wall to the south and west.
Perhaps the most interesting feature we saw, pointed out by FFC, was a rock with a rounded groove running around it. I always assume grooves like this are natural differential weathering;but I expected to see some change in the minerology along the groove or at the bottom of it. I could not see any such in-homogeneity. I looked closely:
This looks like the same rock throughout with no differential weathering to explain it. It really looks like a man made groove to me. FFC thinks it is part and the same scheme of alignments on the hill. The way the groove is placed lines it up with an arc across the southwestern sky.

The most common features on the western side of the hilltop were lines of stones. Here is one, I think it was aligned with true north. You can see 4 or more rocks in a row through the undergrowth.


Geophile said...

Why do you think that top rock is so blackish?

pwax said...

It is schist and still wet from where I brushed off the leaves.