What are rock cairns?

A man stands among a garden of rock cairns.

Even the most casual hiker would likely recognize the stacks of rocks that are often seen along a trail. One might assume they were the work of bored children or the art project of a fellow adventurer, but many explorers have yet to learn that these stacks are called rock cairns and that they carry a variety of meanings.

Rock stacking has been used to create landmarks for many ancient groups of people. The word cairn is believed to be derived from the Gaelic term for a mound of stones which has been used to describe these structures ever since. These structures were used in Scotland as navigational aids, the same way they are used in many national parks today.

Most often, rock cairns are found in deserts where there may not be any other natural landmarks for travelers to use as a guide. Aside from their use as trail markers, these towers have historically been used to mark important sites such as graves or ceremonial locations by other cultures.

Every national park has different guidelines for what rock cairns mean. They are usually used to mark trails, encouraging hikers to follow them. In some places, they mark impressive views, while in others, they mean nothing at all and are only the product of the hikers who made them.

The unauthorized building of these navigational aids is discouraged for several reasons outlined by the National Parks Service. “Moving rocks disturbs the soil and makes the area more prone to erosion. Disturbing rocks also disturbs fragile vegetation and micro-ecosystems,” the National Parks Service says on its website. 

When cairns are built as navigational aids, they are carefully built and often maintained by rangers on the trail. When an unauthorized cairn is constructed, future hikers could get lost or confused by following the cairns, thinking they will lead them on a trail. If a poorly constructed cairn were to fall over, it could cause damage to natural wildlife or to other hikers by ending up in the middle of a trail.

The National Parks Service adopted the Leave No Trace initiative in 1994 to minimize the damages that humans create when they explore nature. Littering and vandalism are easily recognized as practices to avoid, but constructing rock cairns violates these principles as well. 

In being good stewards of the environment, hikers should seek to uphold these principles. The best thing to be done about rock cairns is nothing. Do not build them, and do not tamper with them. Before hiking in a new park, stop to ask a ranger if any of their trails use cairns as reliable markers.


Story by: Lily Brunson

Photos courtesy of Aspen English