"Lace Walls"

In SUSAN ALLPORT’s “Sermons in Stone; The Stone Walls of New England and New York,” the author writes, “In 1871 there were 252,539 miles of stone walls in New England and New York—enough to circle the earth ten times.”
Out of those quarter-million or so miles of “fence,” you’ll find many a “stone wall” that turns “lacey” (Allport's book includes a study of Lace Walls on Martha's Vineyard on pages 120-30).
My friend PW writes at Rock Piles: “It seems to be a classic pattern that a stone wall becomes suddenly higher as it passes over the high point of a knoll. While passing over this high point, the wall also becomes lacey: with one or several holes that you can see through.”

(The row should be higher than I've drawn - or drew a long time ago - so that a person could stand behind it - and resemble the place in CT that I showed Peter and Norman a few years back, where a 3 foot high row makes a "wave" 5 or 6 feet high. I've seen similar in Rhode Island also too.)

People come up with lots of suggestions as to why these lace walls occur – wind spirits pass through them easily, lack of stones to build a tall row of stones as sheep fences, and more. I have a simple explaination: you might be waiting at a kill site and a really high spot would allow you to stand up (to ease your aching back) and keep watch, assuming you believe a lot of stone rows were Native American made and functioned as hunting devices, sort of like a fish weir for deer or other game.
A not so high spot might allow you to squat or sit on a stone, as shown in this recreation made by stealing an image off of Google to add to my friend’s Rock Piles image…

And he's got an animal skin on his head, ears and all, sort of like the effigies on my drawing above, athough he seems otherwise under-dressed for the weather.