| What it is | Stacked-stone trail marker |
| Used where | Above treeline, on bare rock |
| Etiquette | Don't build rogue cairns |
| Difficulty | Beginner |
From the Scottish Gaelic càrn, meaning a heap of stones.
A cairn is a stack of stones built to mark a trail or route, especially above treeline or across rock where a worn path is hard to follow. Hikers use cairns to navigate; building unofficial ones can mislead others, so the principle is to follow established cairns rather than create new ones.
The word comes from the Scottish Gaelic càrn, a heap of stones.
Where you find them
Above treeline and on bare rock, where a paint blaze or worn path won’t work. See cairn vs blaze.
Etiquette
Follow official cairns; don’t build rogue ones — a Leave No Trace issue.
Frequently asked questions
What is a cairn?
A cairn is a deliberate pile or stack of stones used to mark a trail or route, particularly where there's no obvious worn path — above treeline, across slabs, or over boulder fields. Hikers follow a line of cairns to stay on route.
Why do hikers build cairns?
Official cairns are built by land managers and experienced volunteers to mark routes where paint blazes or a trodden path won't work, such as bare rock. They guide hikers across confusing terrain and in poor visibility.
Should you build your own cairns?
Generally no. Rogue cairns can mislead other hikers off the real route and clutter the landscape, and dismantling natural rock disturbs habitat. The Leave No Trace principle is to follow established cairns, not create or topple them.
Sources
- Navigation and trail markers — National Park Service