Thursday, December 04, 2008

Rock Pile site by a swamp by Rt 495

A few weeks ago I showed some pictures of the approach to a site near the highway[Click here] As you drive south on Rt 495 passing the Rt 111 exit, you'll see some dead swamps with water backed up next to the highway. This water is part of Beaver brook, maybe right about here: I also showed some panoramas of this site[Click here]. and you can see medium sized piles built with large rocks, layed out sort of in lines, sort of evenly spaced. You know what I think that means. Anyay, before this site disappears from thought, let's look at some closeup details of the piles there. This was quite a site/sight after several weeks of seeing no significant rock piles:That large vertical piece might not have been vertical before the tree smashed down on the pile. It would be an unusual feature. The water is just to the right in this photo. Some other piles along the edge there:Those are along the waters edge. Back one "unit" of spacing uphill from these, another loose row of piles. Here are some details:A quiet spot, out of the way and cut off by the highway. As usual, there is something rather specific going on here. I hope someone goes back to figure it out.

Glancing again at that map fragment above, I just noticed the hill across the highway: that is the famous "Hill of 500 cairns" - a site damaged by the highway construction. For related stories [Click here and scroll to the bottom].


Norman said...

Are those slate-like rocks common to the area?

pwax said...

Yes, that rock comes from the main ridge of schist - an outcrop representing the edge of the "Nashoba Uplift". In this area there are numerous places where it has been partially re-metamorphosed into plates. For example, Mavor and Dix comment about this rock in their discussion of the Oak Hill (the very same ridge) and the Boxborough Esker.

Tim MacSweeney said...

Just for the record - or perhaps like a broken record - I can't help but notice the stone rows and wonder about them - especially looking back at the "Click Here(s)"