The pathway up from the water to the hill

I was exploring the northwestern part of Horse Hill in Groton, and ended up finding things in the 'saddle' between the hills, adjacent to places I already knew from previous visits. This led me up to a knoll with rock piles that seemed a bit familiar. But as I explored outward, back towards the northwest and downhill from the knoll, I kept finding more piles, each one visible from the previous, and leading back down hill. 
See the blue outline on the map? Note the gully/ravine/small valley that starts at the saddle and goes along the (north) side of the knoll and leads down into the valley to the west. That is the valley of Unkety Brook, which I judge to have been a bit of a thoroughfare, not too distant from the Nashua River. What became obvious was that someone in the past, followed the path of least resistance up from the water to the west, leading to this knoll.  
I have seen that before. At the North Andover Country Club [click here] at College Rock [click here] and maybe a couple other places. The idea is that people of the past traveled by water and, had a number of ceremonials on land that -naturally- used a defined pathway from the water up to the higher ground. Although I did not see a single well defined pathway, the same idea might apply to the piles from Mason NH "rail trail' I reported recently [click here]. When looking at the topo map fragment there, note how both spots 'A' and 'B' are accessible at the head of a valley. I usually interpret this as a tendency towards finding the source of the water. A slightly different interpretation is that getting to these spots follows a valley up from the water to the hill. It may be as much the "source of water" as it is a "path of least resistance". Perhaps these are the same thing. I thought I should name the phenomenon, per the title.
I expect to see grids or burials at the upper end of such a pathway. At Horse Hill there were rock piles with hollows built against boulders on the knoll.

I have written about piles with hollows on boulders being common at Horse Hill and places north of there. Here is a particularly nice one:

Another view:

Do you get the feeling we should pay attention to little niches built into the sides of piles? I see one on the right. On the left the little indentation is so typical, but I do not know what it is for. This is much like one from Mason [see here] where the piles were more decrepit than here.
There were other piles in there that were not built against boulders with hollows. For example:

 The sense of "hollow" persists:

Then we start falling off the edge of the knoll to the northwest but the piles continue:

You can see back down to the water:

Lovely vertical-sided piles seem to guide me along as I go downhill:

Was that a niche? Was that a bent tree?

Maybe. I did not see other possible signs of more recent activity, so it could easily be natural. Here's another something against a boulder:

and here is one of the piles along the way:

(I am guessing Jim P. will like this one). As we get down off the steeper slope...there is stone wall following the contour of the hill. With a couple of piles along it.

This last one, at least, is a familiar "rectangle with hollow" in the form of a 'U' with the opening on the uphill side. These are quite common further to the south. I do not know if I can draw a conclusion from the apparent ages and apparent styles of the different piles shown here.
Update:  As I look at those links above and follow other links they lead to, I see a great deal of similarity in the types of piles present at these places: Horse Hill (and north), College Rock, Mason NH, Gates Pond. We can list features to expect: a path up from the water, vertical sided piles along the way, topping out with mounds with hollows. An occasional short stretch of low wall, an occasional curve of separate rocks (not really 'wall') forming part of an outline or just a curve.