A grammar of white and brown rocks

The title is fanciful but I found another site at a wet spot on top of the hill in one of the Fitchburg State Forests (I described a first wet spot here) where the piles were made with either a vertical fin of reddish brown rock:(the small upright brown rock on the right side of the pile)
(need to look at this a moment to see the vertical fin) or else incorporated a small piece of quartz or white feldspar:
(small white rock on the right is white feldspar)
(another piece of feldspar).

In some cases the piles included both a white rock and a vertical fin of reddish brown rock.
Look at this, in detail:
In another example, the white rock is on the right and the vertical brown rock is on the left:
In still other places the white rock appeared to be paired with another rock which was not necessarily reddish brown.
[I look at this and am sure there is something specific here.]

So looking at these pictures when I get home it really seems that the site where I took these pictures had a specific function which needed these types of piles.

What follows is speculation. I think it is a responsibility to speculate as to what these piles mean or as to what is their function. For quartz, I believe it is used as a focus or conduit of spritual energy. Quartz is rarely used as a rock-on-rock or as a wedge in a split-wedged rock and (presumably) this is because a 'conduit' is in-appropriate for those uses. Yet I saw both things here, for example
When a rock-on-rock made of quartz does appear, it is usually at the end of a line of piles or other rock-on-rocks without quartz, and is the last structure before a drop-off to a lower level. Vertical fins of rock, when in a pile, often are directed in a direction of the water flow (mentioned also at that first wet spot in FSF). What the meaning is of that, or what is the meaning of a red color I don't know. I have heard that the four sacred Indian colors (white, red, yellow, black) may have different meanings to different people. Now we have to ask: what could it mean for quartz to be combined with a vertical fin? The purported meanings of those things fit together easily enough conveying an idea of focused conduits of energy along the direction of the water flow. This is quite possibly nonsense but it is worth puzzling over.