Water Tower Hill in Westford's Greystone Conservation Land

Is this a site of individual prayers?
After finding an interesting see-through structure (blue "X") I crossed the valley and found a rock pile at the foot of the water tower hill.I could see other rock piles higher on the hill above (see the water tower up there?):So I went uphill, zigzagging back and forth between small rock piles, each built with a handful of smaller rocks on larger supports. For example:I don't know how to classify this site. It is typical and reminds of similar hillside sites (eg Flagg Hill, Stow or the southeastern foot of South Manoosnoc in Leominster). [Also like this from the other day and about a mile or two from this spot] The piles are not arranged in lines or evenly spaced and the site lacks the structure of a marker pile site. At most here there might have been some slight clustering of the piles into little groups. I hate to cop out on this but when the piles are not in obvious relation to each other but are occupying one specific topography, I imagine there is something special about this place that called for rock piles by more than one person over a more extended period of time. In other words a site individuals would go back to.
But of course I really have no evidence or special observations about these places one way or the other. There were a few other rock piles here and there on the hill.