Out hiking? Here’s why you should leave those stones unstacked and those stacks untouched.

Sometimes called cairns, these rock stacks can serve as critical trail markers, and some carry cultural significance, as well. Others are purely decorative, built by visitors who enjoy designing these towers in nature, often for the sake of sharing images of delicately balanced stones on social media. Besides the fact that it violates the Leave No Trace program’s ethos that should be honored by visitors to our national parks and other public lands, here’s why you should resist the urge to create a rock pile, during a pandemic or otherwise.

Trail designers put a lot of thought into where and how they place way-marking cairns to safely keep people on the path, says Jake Case, a former National Park Service ranger and a Grand Canyon National Park guide. But rock stacks erected by trail users may have the opposite effect. “If a hiker ventures off-trail and builds cairns to mark their own route, that could lead others astray from the actual route,” he says. “You can very easily end up in dangerous places.”

Even Case, an experienced hiker and guide, has been misled on occasion by strangers’ rock stacks. While he says he always gets back on track, someone else might not be as lucky: They could lose time (and end up stuck out after nightfall) or fall from a cliff, for example, if not familiar with the terrain.

And, of course, if you build cairns to mark your own route, there’s no guarantee someone won’t move your stacks or build their own, which means you might also have trouble finding your way back.

Miki`ala Pescaia, a Native Hawaiian cultural practitioner and the chief of interpretation, education and volunteers at Kalaupapa National Historical Park on the island of Molokai, says this behavior can strain local resources. “We have such dynamic weather and terrain [in Hawaii]. . . . We’re so prone to landslides and flash floods, we’ve got steep cliffs,” she says. “Our emergency services frequently have to rescue hikers because they don’t stick to the trails.”

You should also consider the risk in reaching for stones in the wild; depending on where you are in the world, picking up a rock might mean putting your fingers in proximity to scorpions, snakes and other creatures that live or hide out there.

Pescaia said that visitors “want to go where nobody else has gone before.” But heading off-trail, and leaving unofficial cairns that lead others to follow you, doesn’t just endanger humans, she says; it can put local plants, insects, animals and more at risk.

“We’ve got birds nesting in [the rocks] and insects living under them. Some plants incubate in the crevices,” Pescaia says. “We have very fragile ecosystems here in Hawaii. Once you move those rocks around, you have the potential to kill endangered species.”

At Haleakala, a volcano and national park on Maui, park staff members sometimes build purposeful rock shelters to protect those species. So, Pescaia says, it’s frustrating when visitors move rocks or kick them over, exposing the seedlings of rare and endangered species such as the Haleakala silversword.

When rocks are relocated, this also can destabilize the soil and make the area vulnerable to erosion. In the case of removing rocks from rivers and other water bodies, you may be disrupting aquatic habitats and, in extreme cases, could even be affecting the natural flow.

In some cases, Pescaia says, removing rocks from existing cairns disrupts cultural knowledge and traditions. “There are so many different rock structures, and they’re very specific in function,” she says. “To the untrained eye, they may look similar, but they’re not.”

 In Hawaii, Pescaia says, rock structures of various sizes and configurations are dedicated to fishing, farming, offerings, medicine and navigation, for example. “There are a number of people living in Hawaii that rely on that information and the function of the stones,” she says.

 In some cultures, cairns also can indicate burial sites, says Matthew Nelson, an archaeologist, outdoor educator and the executive director of the Arizona Trail Association. “Can you imagine what it would feel like if you and your family went to the graveyard to visit one of your ancestors and somebody had kicked over the headstone?”

Len Necefer, assistant professor of American Indian studies at the University of Arizona and a member of the Navajo Nation, says that some cultures also use rock structures to denote sacred or historical spots, and this varies from tribe to tribe.

So, err on the side of respect. “Don’t move rocks, don’t touch them, don’t remove them from [existing] structures, and don’t build new structures,” Pescaia says.

For some people, constructing stone stacks is a meditative practice or photo opportunity. But what you might not realize is the next person who stumbles on your creation may feel differently. “We use the outdoors as a way to escape. We’re out there to get away from society, cars, electricity . . . all the systems we’ve built,” Nelson says. “So for people that are seeking deep, solo, wilderness experiences, [seeing man-made cairns] snaps them out of that.”

In Acadia National Park, stone stacking has become such an issue that staff members have had to undo thousands of unofficial ornamental cairns in recent years. They continue to ask visitors — through educational signage and materials — to respect the park and the official trail-marking cairns and to resist the desire to design any rock “art.”

Arbitrarily building these types of rock piles with no regard for official or cultural purposes or environmental issues is “almost like graffiti,” Pescaia says. It announces, “I was here,” just without the spray paint.

Rather than making your mark on the natural environment, aim for the opposite. “So many of the recreation trails that we use today were traditional footpaths,” Nelson says. “Chances are, you’re walking in somebody else’s footsteps,” yet you aren’t bombarded with signs that they were there [beyond the actual path], and you should ensure the same is true for those who come after you. Follow Leave No Trace principles, and, Nelson says, consider “how you can move across the landscape in a thoughtful way so that thousands of years from now, there is no direct sign that you were there.”

One way to ensure you won’t need to build rock stacks for navigation is to be prepared, Case says. “Almost everybody has GPS capabilities on their phones, but you can’t rely on the phone to stay fully charged or [that you will] maintain service. So, you should bring a map and a compass and know how to use them. That way, you’re not reliant on leaving rock stacks in order to get back.” You can also consider hiring a local guide if navigation is a concern for you or if you’re keen to learn more about the cultural and historical context of the lands you’re traversing.

If you come across places where a navigational resource is insufficient or it seems signage or official cairns are needed, notify the land management organization so they can address the issue. In some situations, such as washes where a riverbed crosses a trail to make the route unclear, Nelson says there are approved places for building cairns.

If you have a desire to create while connecting with nature, Case recommends bringing paper and a pencil rather than reaching for rocks to stack: “You can sketch the landscape or whatever else inspires you instead of using your creativity on the landscape.”

Of course, you can also get creative with photography, for example, without touching or disrupting the environment. “Using a digital platform to preserve an experience is better than taking a rock or building or rearranging something” in the natural landscape, Nelson says.

And for those who find rock stacking therapeutic, Nelson suggests saving that activity for your own yard or a city park rather than wild areas. “There are places — including national scenic trails and national parks — that have been designated as having significant natural and cultural resource value,” he says. “It’s our opportunity and responsibility to protect those in perpetuity and keep them in the most wild and primitive state that we possibly can.”