No rock is equal, just as no stack of rocks is equal.

Anyone who has explored Colorado’s outdoors long enough has seen them: cairns, derived from the Scottish Gaelic term “carn,” meaning pile of stones. It’s a term that has traveled space and time to this state’s Rocky Mountains, which are very rocky indeed. Where trails are less obvious amid the rubble, cairns lead the way.

Wrote Graham Ottley, education director of Colorado Mountain Club: “These stone markers originated in Scotland but have become essential navigation tools in Colorado’s alpine environments, particularly above tree line where trails are difficult to follow.”

Sometimes, however, cairns lead the wrong way. Or they are built for fun, for decoration, serving no purpose but aesthetic, as some see it. Others see cairns as eyesores — “cairn Karens,” as Alex Derr has heard critics called.

Derr runs The Next Summit, a blog that aims to be an educational resource on Colorado’s mountains. Another popular resource is 14ers.com, a site focused on the state’s 14,000-foot peaks where Derr has seen forums flare over the topic of cairns.

If ever the image of a conical pile of rocks was charming and idyllic, inspiring dreams of alpine wonder, that might not be the case today.

“They are sort of a good symbol or like a metaphor for what’s happened with mountaineering in Colorado and fourteener culture really over the past 100 years,” Derr said.

A hundred years ago, summit seekers did not have 14ers.com, downloadable maps and GPX files. People then likely had cairns, for which many of today’s peak baggers are still grateful, reassured by directional help that is physical rather than digital. And then there are those who see cairns infringing upon Leave No Trace, the set of standards at the heart of those online debates.

“There are, in my view, three different types of cairns,” said Lloyd Athearn, executive director of Colorado Fourteeners Initiative (CFI).

CFI constructs and maintains summit paths deemed sustainable. In doing so, CFI abides by U.S. Forest Service specifications — including guidelines for cairn building. Those are outlined in the federal agency’s 307-page Trail Maintenance and Construction Notebook.

One might stack rocks shin- or knee-high, but not one authorized by the Forest Service.

Reads the notebook: “Cairns are not a few stones piled one on top of the other (sometimes called a rock duck), which can easily be kicked over.”

Per the official blueprint, cairns should measure 3-4 feet wide and stand 4-6 feet tall, with “a 6 1/2-foot guide pole in the center to distinguish the cairn from other piles of rock or snow-covered mounds.”

CFI builds these to keep hikers undoubtedly on the right route.

Otherwise, “people might be cutting across super saturated soils with fragile plant cover,” Athearn explained, “and all of a sudden you can get a huge amount of impact.”

Then there’s a second type of cairn — “many that are unofficial markers,” wrote Ottley, with Colorado Mountain Club. Those “rock ducks,” those crafted by the everyday hiker, “should be treated with appropriate skepticism,” he wrote. Maybe they lead the right way, maybe they don’t.

A third type of cairn could be called “ornamental,” to borrow a word from the National Park Service (NPS). Those pleasing to one viewer and detrimental to another.

“A bit like littering using a natural object,” Athearn said. “Some people get super offended by them, and other people think they’re the coolest thing in the world.”

They “can often become a problem for hikers who think they are supposed to follow them,” reads an NPS article. According to the agency, cairns are “carefully maintained” by some parks while other parks ban them.

“However, they all have the same advice,” the article reads. “If you come across a cairn, do not disturb it. Don’t knock it down or add to it.”

That, by the agency’s account, is following Leave No Trace: “Moving rocks disturbs the soil and makes the area more prone to erosion. Disturbing rocks also disturbs fragile vegetation and micro ecosystems.”

Proponents insist proper cairns uphold other ethical tenets: keeping people on the trail and thus respecting plants and wildlife. However obnoxious and unnatural to some, the benefits of those massive, Forest Service-authorized cairns are “significant,” Ottley wrote. “They enhance safety by remaining visible even in winter conditions, require no technology to function and connect modern climbers to historical traditions.”

Cairns have been traced to prehistoric traditions. Civilizations and tribes around the world stacked stones as part of rituals, to mark burials and to commemorate sites. When construction crews come by cairns, the law requires archaeological review.

Cairns were also built for hunting purposes, according to a 2017 thesis out of Colorado State University.

The thesis was based on previously documented game drives along Rollins Pass, where projectile points had been dated thousands of years ago. Several cairns have been among other rock structures studied high on the pass outside Winter Park, the thesis explained. Several rock walls and “cairn lines” also helped direct man and beast to certain “kill zones” and harvesting places.

It was research that caught Derr’s curiosity. He’s broadly curious about cairns, about how they’ve come to represent this era of mountaineering.

“In the old days, that was the route; early 1900s, that’s how you did it, and it was a small community of people,” he said. “But with the way it is today, everybody is building cairns everywhere, and it kind of proves the point that things have changed, and we also have to change the way we manage that.”

The internet has spelled “a bizarre phenomenon,” Athearn observed. “With more information, it seems that intuitive, navigational abilities have not been developed as well.”

Cairns can help, he said, and they can also lead less-skilled people astray. Even a well-traveled climber such as Athearn has met the conundrum.

He was once high on Wyoming’s Grand Teton alongside a partner. “All of a sudden, man, we could not figure out where the route was,” Athearn recalled.

They cautiously followed one cairn. They cautiously followed one after another until they felt caution give way to a much different, most welcome sensation: “a certain level of relief,” Athearn said.

And then success.