“Cairns are a nuanced topic,” Death Valley spokesperson Abby Wines told SFGATE in a statement.

While some of the cairns that mark hiking trails and routes are done by park rangers, most are created “by hikers trying to pay it forward to help other hikers,” Wines told SFGATE. “These cairns are useful and should be left where they are.”

She also said that sometimes cairns are used to mark historic features.

“Cairns were used to mark boundaries of mining claims and land survey points in this area in the late 1800s and early 1900s,” she said. “Now these are helpful for historical archaeologists and should be left in place, just like historic trash around old mining camps should be left in place.”

Wines said that guests should never build cairns but also should avoid knocking them down.