Once more, with feeling....another trip to Falulah Brook headwaters

I tried again to circle these headwaters of Falulah Brook in northern Fitchburg. This time my plan was to walk along the southern edge of the brook, cross somewhere near the Worcester/ Middlesex county boundary, and come back along the northern side of the brook. Instead I crossed lower down, by mistake, and ended back near the beginning point earlier than I had wanted. I found a wonderful little Wachusett Tradition site there (outlined in red). But I had wanted to circle further upstream, so I reversed my steps and went back along the northern side until I got to another Wachusett Tradition site I saw in the past and, when my camera battery started to crap out, I circled back and ended by returning via the initial path along the southern side of the brook. Not important details, except that this was a walk with many small brook crossings and the rocks were icy, where wet. So it was difficult to score top points for brook crossing elegance - but I managed to keep my feet dry.

First off, next to Ashby West Rd, as you step into the bushes on the west side of the road, this is a messy pile I have photoed several times before. I liked the colors this time:
Walking and crossing some brooks, I was [I guess] on the north side of the brook when I noticed a single rock-on-rock in the boulder field. Why that one rock-on-rock? Notice the split boulder it is next to:Then I saw a couple of faint structures, seeming to lead to where a well built stone wall terminates at a nicely squared-off ending. And as I walked over to look at the stone wall, I noticed some larger things looming in the background:Here was one Wachusett pile:Note that this pile is entirely made from large rocks but without any smaller rocks involved. I see this frequently enough and, here, start to wonder about it. Why would one pile be made exclusively from larger rocks, while others are made with smaller ones? Compare with large pile in this scene, which I stepped into:
Let's have some other views of these fine piles. Here is the horizon view:Details of the larger mound:Note this is more of a "double chambered" example - There appear to be two separate hollows.

Here is a closeup of the vertical sided pile.This is a typical example of the kind of smaller piles one finds, like satellites around the larger Wachusett mounds.

There were numerous other satellites:

I like this clear relation between mound and satellite. Note the direction of the vertical side, note how the hollows are placed in the larger mound:Finally, just a brief look at some piles from the previously discovered site (uppermost blue oval on map). Here is one where you probably neither can see the rectangle, not the hollow. It is pretty worn down.I just want to compare it with this other one from there. It is another example of a pile built only from larger rocks.
Summary: Standard Wachusett Tradition site includes mounds with hollows surrounded by smaller satellites that have some of the attributes of marker piles. [By the way, I think it is a complex machine for getting the soul to the underworld]. Sometimes, one of the mounds will be made only from larger rocks.