Cairn rocks – what are they and how do you use them when hiking?

Rocks have many significant meanings when stacked into piles called ‘cairns’. Rock cairns are essential to navigating on the trail. Find out how to use them...

6-minute read

Key takeaways

  • Navigational aid: Cairn rocks are man-made stacks of stones used to mark trails, especially in areas where paths are unclear or landscapes are featureless.
  • Historical significance: Cairns have been used for centuries, serving various purposes such as marking graves, aiding navigation, and even assisting in hunting strategies.
  • Environmental impact: Building unauthorized cairns can harm local ecosystems by disturbing habitats of small creatures and plants; therefore, hikers are advised not to create their own cairns.

In a hurry? Jump to a relevant section below:

What are cairn rocks and how do I use them to navigate?
The history of rock cairns
The problem of too many cairn rocks
Follow the cairns to stay safe
FAQs

What are cairn rocks and how do I use them to navigate?

What are cairn rocks? Cairns are manmade stacks of small rocks. In the world of hiking, you find them marking the trail when it is not clear which path to take.

I’ve been on hundreds of trails marked by cairns. Sometimes, the cairns have been essential to help me find my way. After having used them so many times, I am always looking out for them. It’s such a feeling of relief when you’re hiking cross-country and you spot that next cairn.

If you’re a hiker, read my guide on what cairn rocks are and how to use them. I’ve also researched the history of rock cairns. And gathered expert advice on why you should never build your own cairns.

The word ‘cairn’ originates from the Scottish Gaelic word càrn, which means ‘mound of stones.’ In my experience, cairns are mostly no higher than knee-height, but they can be much bigger. They are usually conical in shape.

A small rock cairn guiding the way through long grass
A larger, easier-to-spot cairn
Me, very happy to reach a large pile of rocks marking the summit of a mountain

Trails through long grasses are easier to see than trails through desert or areas with little fauna. So, rock cairns are especially useful if you’re navigating through a featureless landscape. They can help you figure out if the path you are following is actually a path, or if it’s a dry stream bed for example.

On the flipside, trails passing through areas with lots of vegetation can become overgrown if not used often. You might not be able to see the trail unless a cairn of rocks is marking it.

We would never have been able to follow this trail if there were no cairns!

Ever been up a mountain when cloud or fog creeps in? Visibility is down to a few yards and all you can make out are shapes. That’s when seeing a larger cairn to guide you in the right direction is very useful!

On trails where you’re off the beaten track, piles of rock cairns often mark the track. When you find one cairn, you can always see the next cairn, and so you know which way to go. But you should never rely upon cairn rocks as the sole method of navigation. It’s possible a cairn can be missing if someone has kicked it over. Or, more likely these days is that someone has built a cairn of rocks just so they can take a photo of it for social media. So, it’s not actually marking the trail.

Once, I was on a remote mountain trail with a friend. We had pre-planned the route using hiking guidebooks, maps, and a couple of apps with GPS waypoints. We decided to try a shorter ‘plan B’ route back down the mountain. The route had cairns, and was detailed on one of our apps. It required a lot of scrambling, and careful observation to find the cairns. But then suddenly we couldn’t see the next cairn. 

We spent 20 minutes scanning every detail of the mountain and there were no cairn rocks. The app and the guidebook said there was a route, but all we could see was a very steep slope that ended in a sheer drop. We knew that if we scrambled down looking for cairns that there was no way back up. That’s a risk you don’t want to take. We backtracked and stuck to our ‘plan A’ route. The lesson is, that if you can’t see the next cairn, do not keep going because you could end up stuck or lost.

You should pre-plan hikes by consulting a topographical map, and/or a guide book. I use an app, map and books, plus rock cairns while I’m on the trail. Are you worried that you would need to build your own rock cairns to avoid getting lost? Then you should hire a guide instead. It is not advisable to build your own cairns. In some national parks it is illegal. Keep reading to learn why.

How a trail looks on Wikiloc
Bates cairn, Acadia National Park
A topographic map is useful to show the terrain

Not all cairns are conical in shape. Bates cairns look more like a small table. A Bates cairn is a long rectangular stone balanced on top of two smaller rocks that act like table legs. On top of the rectangular slab of stone is another stone pointing to the trail. These kind of cairn rocks date back to 1896, when a man called Waldron Bates created them in Acadia National Park in the USA. 

Standard cairn rocks replaced Bates cairns during the 50s and 60s. But since the 90s, rangers at Acadia Park have begun restoring Bates cairns. Now the park has both types.

The history of rock cairns

Cairns have been around for centuries and have many other uses and significance. In the prehistoric era they marked graves or served as memorials. Scotland has a famous site of prehistoric burial monuments called Clava Cairns near Inverness, which is about 4,000 years old. Rock cairns used at burial sites are also called barrows, dolmen, stupa or tumuli.

Clava Cairns near Inverness, Scotland

Before heading into battle, members of Scottish clans would each place a rock in a pile. According to Scottish folklore, if they returned from the war, they would remove one rock. The remaining piles of rocks would serve as a memorial for deceased clan members.

Around 500 years ago in the Blackfeet Indian Reservation in the US Rocky Mountains, native Indians drove huge herds of buffalo to jump to their deaths over a cliff edge. Tribes had first built many cairns made from piles of rocks. The cairn rocks restricted the areas where buffalo could roam and funnelled them towards the cliff. These ‘buffalo jumps’ enabled the Indians to hunt more than enough buffalo to feed them for months.

In the UK, the Brown Willy Summit Cairn in Cornwall reaches over 16 feet high and has a 79-foot diameter. No one has ever looked, but rumor has it that the cairn marks the grave of a Cornish king.

There is also some evidence that the Brown Willy cairn may have astronomical significance. There are many ancient manmade rock constructions in the area. One structure is the Stannon stone circle. If you stand in the center of the Stannon stone circle and watch the autumn equinox sunrise, it aligns perfectly with the Brown Willy Summit Cairn.

Norse sailors in Scandinavia used huge piles of rocks to aid navigation through fjords in the days before lighthouses. 

Nordic cairns at Djupvatnet lake, Norway

The Andes mountains and Mongolia steppe feature many ancient cairns. Hundreds of years ago, different cairns indicated trails to either safety, other villages or food sources. In Peru, cairns known as apachetas were historically built for spiritual reasons – placing a stone on a cairn was a sacrifice for the gods.

In the USA in the 18th and 19th centuries, new settlers used cairns to mark out land boundaries. Some of these are still visible in the Montana and Colorado mountains. Later sheepherders adopted them, to help them figure out distances. They were called ‘stone johnnies’.

Cairn rocks are also created by people as symbols of faith and religion. The famous Camino de Santiago trek through France and Spain attracts many pilgrims. The end of the route is the grave of Saint James. The tradition is for hikers to add a rock to several piles of stones along the way. Not every hiker is religious, but the adding of a small rock to a bigger pile has become a way of saying “I was here.” 

As well as cairns, these posts mark the way on the Camino de Santiago
In inuksuk made from flat rocks

In Canada, an image of an ancient cairn is often used as a national symbol. The people of Arctic North America such as the Inuit and other tribes, built inuksuk. Found in Canada, Alaska and Greenland, these cairns aided navigation in a landscape with few natural landmarks.

The problem of too many cairn rocks

Correctly placed, cairns are a useful navigation aid. In many national parks, the rangers are responsible for maintaining cairns. They also check they are in the right locations. 

The problem is that the general public has a tendency to build their own cairns, or rock stacks. The word ‘cairn’ is only used for an “established pile of rocks used to mark a trail”, say Leave No Trace’s Stephanie Whatton and Andy Mossey. 

Building rock stacks can have a devastating effect on wildlife. Insects, invertebrates and small mammals shelter under rocks to give birth and avoid predators. Many creatures live under rocks. Move their rocks and you expose them to predators. Or, you could destroy the home of an entire colony of insects. 

Along the river edge, fish lay eggs under rocks. Removing that rock could expose the eggs to prey. The Ausable River Authority has some advice on why building cairns from river rocks is a no-no.

Scorpions and snakes hide under rocks. Do you fancy annoying a snake or scorpion by removing their rock? I didn’t think so. 

Scorpions hide under rocks

Rocks also provide shelter to seedlings. In Maui, the rare Haleakala Silversword needs rocks to protect it. Park rangers educate visitors on how to avoid damaging the terrain where these endangered plants live.

Removing stones and rocks also leaves the earth exposed to the elements. Erosion will take place more rapidly on soil once rocks have been removed.

One person moving a few rocks doesn’t have a big impact. But in 2021, the USA’s National Park Service received 297 million recreational visits. And this number is lower than the average due to Covid restrictions. Visitor numbers will increase year on year. What if 297 million people moved a few stones to create their own rock stack? Ecological disaster. 

How would you know which cairn of rocks to follow if the park is scattered with rock stacks / cairns built for fun? You wouldn’t know. You’d get lost. Don’t build your own cairns. 

The National Park Service advocates the Leave No Trace principals, which you should be familiar with if you are a hiker. One rule states: “Treat our natural heritage with respect. Leave plants, rocks, and other natural objects as you find them.”

Follow the cairns to stay safe

Now you can use cairn rocks to help you navigate while hiking. I hope you follow the expert advice and choose NOT to create your own rock stacks in the backcountry. Enjoy your next hike and be grateful for the cairns!

FAQs

What are hiking cairns?
Hiking cairns are stacks of rocks placed along trails to mark the path and guide hikers, especially in areas where the trail may not be clearly visible.

Why are cairns important for navigation?
Cairns help hikers navigate by providing visual markers in open or rugged terrain, ensuring they stay on the correct path and avoid getting lost.

Can I build my own cairn while hiking?
It’s generally discouraged to build your own cairns as it can disturb the local ecosystem and create confusion for other hikers who rely on official trail markers.

What should I do if I see a cairn while hiking?
Follow the direction indicated by the cairn to stay on the trail, and avoid disturbing or adding to the cairn to preserve its intended use and the surrounding environment.

Stack up knowledge, not rocks

I have more navigation advice and tips for staying safe on the trail. Stack up your knowledge by reading more:

How much water should I drink when backpacking?
What is ‘Leave No Trace’? A simple guide for protecting nature
Hiking snacks: 20+ easy, nutritious snacks for the trail
13 surprising health benefits of hiking

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