Roadside Attraction - a suspicion confirmed

I mentioned how suspicion turns to certainty when, as you drive bye at 70 mph, you finally scan a few feet of the forest floor containing a rock pile and you see it for certain. I am extremly pleased to confirm a rock-on-rock in the median strip of Rt 495 southbound just before the Rt 38 exit in Tewksbury/Lowell. If you happen to pass this place often enough you might spot it too: it is the last big rock before the woods end and we get down to a grassy median on approach to Rt 38 and Lowell. Don't expect a photo anytime soon, I have been scanning this portion of the median for several months and I ain't gonna go there on foot. Of course what this tells us is that there was perhaps a more extensive site here once before the highway went in. Actually I found a couple of piles in the woods south of the highway - just across from here - and perhaps this was once all a contiguous site. Spotting a pile along the highway tells us something else which is probably more important: the density of rock pile sites is quite high. There is a more quantitative statement but we'll postpone, for now, applying ideas from stereology. For now I will simply make the claim: there are four places I can see rock piles from the car as I drive from Concord to Andover. Four sites in 30 miles along any random cross-section gives a density estimate - I am too lazy to do the math. One other thing: I have been south of the highway there because I was suspicious of those woods. I scan the median, because I really thought I saw something in there (not today's find but something else). But what about north of the highway? That is yet another suspicious looking piece of woods, right in someone's back yard. That is a place I want to get on foot, it looks like a perfect spot for rock piles. And the reason this is so much fun is because of the connection between guessing where there are rock piles and confirming them. It validates the intuition.