National Park rangers are pleading with hikers to stop building towers from rocks on hiking trails and riverbeds.
While stacking up stones might seem harmless, it can do a surprising amount of damage to the environment – particularly if taken to extremes. Ranger Cathy Gatley came across a creek bed in Cania Gorge National Park, Australia, where every stone had been stacked.
This can lead to erosion and could even cause flooding as there's nothing to slow the flow of water. "The rocks help to absorb water, and they prevent runoff," Gatley told ABC News. She explained that they also provide a habitat and refuge for plants and animals, and moving them leaves creatures without a place to shelter, or to hide from predators.
Other organizations, including the Reach Museum in Washington, US, have warned that decorative cairns can also be dangerous to animal and children if they topple.
The building of rock cairns (originally built as memorials, for surveying, and to help people navigate in the wilderness) has been a controversial topic for many years, and modern-day stacks are often built by people who want to leave their own mark on the landscape or take an interesting picture for Instagram.
Instead, Gatley urges hikers to follow the principles of leave no trace. "Most of us go to national parks to really experience that natural scenery, and just like scratching your name into a tree, rock stacks are seen as vandalism," she said.
In fact, visitors found stacking stones in Australian National Parks can be fined up to AU$600 (about $420 / £340) for 'unauthorized works'.
