Have a closer look
Lichen is a measure of the purity of the air; clearly, here, the air is clear and good, despite being relatvely close to Edinburgh. I love the textures of a dry stane dyke, and would have loved to have learned how to do it. That's not likely to happen now, of course.
I've had a thing about walls, and stone in general, for many years. I find them fascinating. The softness of these Scottish dykes contrast beautifully with the flint walls of Norfolk, which I find, have a much harder texture, and are more angular .
To me, though, they share more than they contrast. There are miniature stories in each wall; the marks on each individual stone, and the way they interact together. Gorgeous.