Key takeaways
- A cairn is a stack of stones marking a trail or route where a path is hard to follow.
- They're common above treeline and across rock or snow, where blazes and tread don't work.
- Navigate by spotting the next cairn from the current one — they form a connected line.
- Don't build or dismantle cairns: rogue ones mislead hikers and disturb the landscape.
From Scottish Gaelic 'càrn', meaning a heap of stones.
What a cairn is
A cairn is a deliberately stacked pile of stones that marks a trail or route. Where a path crosses bare rock, climbs above treeline, or traverses snow — terrain with no soil to wear a tread and no trees to paint — cairns become the primary way the route is marked.
How to follow them
Cairns work as a chain: from each one you scan ahead, locate the next, and walk to it. They form a connected line across otherwise featureless ground. In fog or whiteout, don’t leave a cairn until you’ve found the next, and back it up with map and compass.
Above treeline on a rocky ridge, a hiker pauses at each cairn to spot the next stack before moving — staying on the established line even where there’s no visible path underfoot.
Cairn etiquette
Follow official cairns, but don’t build or topple them. Rogue cairns lead hikers astray, and moving rocks disturbs fragile alpine soil and habitat, against Leave No Trace ethics. Cairns differ from painted blazes — see cairn vs blaze.
The bottom line
Cairns are the trail's stone signposts where blazes and tread give out, guiding hikers across rock and alpine terrain one marker at a time. Follow the established ones carefully — especially in poor visibility — and resist the urge to build your own, which misleads others and harms fragile ground.
Frequently asked questions
What is a cairn used for?
A cairn marks the route where a trail is otherwise hard to follow — above treeline, on bare rock, or across snowfields — where you can't paint a blaze on a tree or see a worn path. Hikers navigate by spotting and walking from one cairn to the next.
Should I build my own cairn?
No. Building unofficial cairns can mislead other hikers off the real route and, by moving rocks, disturbs soil, plants, and habitat. Leave No Trace ethics ask you to leave the landscape as you found it — follow established cairns, but don't add to or knock down the trail's markers.
How do you follow cairns?
From each cairn, scan ahead until you spot the next one, then walk toward it; the markers form a connected line along the route. In poor visibility, don't move on until you've located the next cairn, and use your map and compass to confirm you're still on course.
Sources
- Trail marking & navigation — American Hiking Society
- Leave No Trace principles — Leave No Trace Center for Outdoor Ethics