Tourists are ruining the amazing 'cannonballs' at Theodore Roosevelt National Park

Cannonball concretions, Theodore Roosevelt National Park, USA
(Image credit: Getty)

People are vandalizing rock formations at US National Parks, and destroying unique geological features that have taken millennia to develop. Earlier this week, photographer Kevin Dunn shared a picture of graffiti on one of the spherical cannonball concretions at Theodore Roosevelt National Park in North Dakota, which is a particular hotspot for vandalism.

"This is on one of the 'cannonballs' at the Cannonball pull off," Dunn wrote, alongside a photo of a name and date scrawled on the rock using a permanent marker three years ago.

Graffiti is a serious problem at US National Parks, and it's not always possible to remove. Scouring ink and paint off rock often requires strong solvents, which can be damaging to local plants and wildlife, while sandblasting it away accelerates erosion. The act of vandalism itself can also cause lasting damage to delicate formations.

The cannonball concretions are spherical stones (some of which are several feet in diameter) were slowly created  by water seeping through porous rock and causing sediment to stick together. Over time, layers of sediment build up to create a ball, like a pearl forming around a piece of grit in an oyster. These concretions form underground, and are eventually exposed by erosion of the surface rock. 

They are an amazing feature, but they are also a graffiti hotspot. According to the National Park Service, every single one of the exposed concretions has been tagged or marked in some way.

"The sandstone in the badlands is very soft and naturally erodes," explains one Park Ranger in an informational video, which you can watch below. "If you add to that erosion by carving your name into it, you are speeding the process. If every visitor added graffiti to that cannonball, 100 years down the road it may no longer be there."

You can help protect them by not adding to the graffiti yourself, and educating others about the importance of leaving no trace.

Cat Ellis

Cat is the editor of Advnture, She’s been a journalist for 15 years, and was fitness and wellbeing editor on TechRadar before joining the Advnture team in 2022. She’s a UK Athletics qualified run leader, and in her spare time enjoys nothing more than lacing up her shoes and hitting the roads and trails (the muddier, the better), usually wearing at least two sports watches.