When you hike through rugged trails, atop mountain peaks, or along coastal paths, you may come across a stack of rocks carefully balanced on top of one another. These are called cairns, and they’re far more than just a random pile of stones. Cairns have been used by different cultures around the world for thousands of years, serving a variety of purposes ranging from navigation to spiritual symbols.
A cairn, by definition, is a human-made pile or stack of stones. While their simplicity might suggest otherwise, cairns have deep cultural, historical, and practical significance. Found in many regions across the globe—from Scotland to North America, the Himalayas to the Andes—cairns have played an important role in guiding travelers and marking significant locations.
If you are interested, here is a bit more information about Cairns.
Judy Lindo Photography 
I am one of those not in favour of random cairn building on hills. They can lead walkers astray.
LikeLike