Cairns are piles of stones used by many different cultures for various purposes.
They are generally found in wilderness areas such as mountains and deserts to help guide travelers. or mountainous regions, and also in barren desert and tundra areas as well as on coasts. Tibetans also use cairns known as ovoos for Buddhist ceremonies.
So make a cairn. Help out a fellow hiker and practice the patience-testing art of cairn making.