Rock piles with tails

I am going to keep talking about this topic, since it came up in my explorations as described here and here. After writing those posts I had feedback from reader Keith that he has seen piles with tails (south of the Mass. Pike??) and from Norman Muller who first documented piles with tails in his description of the Stockbridge VT Cairn site [click here, then go to the third page and scroll down]. I'll quote from Norman's article:

"Similarly, more than 200 miles to the south, at the Oley Hills site, is Platform B (Fig. 15), a large stone platform with a terrace-like extension at the north end that ended at some large boulders, from above looking like the curved tail of a scorpion (Fig. 16). The similar morphology among these three examples is more than a coincidence, I believe, and reflects a widespread cultural and architectural response to the landscape. " (Take a look at Figures 4, 12, 14, and 15 from his report.)

So that is the background; I came to the same conclusion about a particular culture. Let's collect together some of the pictures. Here is Norman's Fig.14 (from VT)
And his Fig 15 (from PA, showing the tail with the main pile to the left of the picture)
And two examples I saw the other weekend (from Carlisle)
And I must add also the picture of the main pile at Apron Hill, Boylston MA
Now, for better or worse, I took Apron Hill as the defining "archtypical" example of the Wachusett Tradition. So I am obliged to see these other sites with the same peculiar rock pile type as other examples of that Tradition and re-use the name. [It is just a word but it is in my head now; serving to organize other thoughts - a point of reference.]

A couple of questions:

• what is the tail for?
• are all tails alike (some have more of a knob on the end)?
• what is the distribution of piles with tails?
• why do the tails curl clockwise only [so far anyway]?
• what is the cause or purpose of the hollow so often seen at the opposite end of the pile from the tail?
  

Along the lines of the question about where these piles are found, I am currently associating them to Wachusett and the inland regions. But I find these piles mostly low down near the water (so they are not necessarily at a high "outlook", as I first thought). So my hypothesis is: look for these piles along the south and eastern side of bodies of water, in the inland regions about Mt Wachusett. To test this I went out last weekend, driving 50 miles to get somewhere that seemed likely - parked, stepped out, and saw a pile with a tail. I'll post about that soon.