Erosion made southern Utah what it is — a spectacle of red rock canyons, towers and arches that attract millions of visitors from around the world each year.
But the same forces of wind and water that carved those geologic icons are still at work today, often undermining the roads that allow visitors to enter this wild landscape.
The tug-of-war between outdoor recreation infrastructure and Mother Nature was on dramatic display earlier this year when a massive chunk of the Kolob Canyons Road collapsed in the northwestern section of Zion National Park. During Utah’s extra wet winter, erosion undercut the road and an entire lane of pavement slid away.
Park public affairs specialist Jonathan Shafer said the ongoing movement of rock is just Zion being Zion.
“This is a dynamic landscape. It's always changing,” Shafer said. “Every rock that you see that's up above us one day is going to move down. Every rock that you see down below us came from somewhere up above.”
Now, the park has begun the process of rebuilding the road, which is the only way to drive into this relatively remote part of the park.
On a steep slope overlooking the towering red rock formations of Kolob Canyons, an excavator scoops into a mound of dirt where the road used to be. Below, workers unroll a black blanket of geotechnical grid — a synthetic material meant to reinforce the 8 feet of soil that’ll eventually underpin the rebuilt road.
When it comes time for a project like this, he said, the park is always trying to learn how to build it back better than it was.
“Our goal when we're done here is that we keep the park a park, we protect this place, and we also maintain access so that folks are able to come here and enjoy it.”
If all goes well, Shafer said, the Kolob Canyons Road will reopen by the end of 2023, with 6,000 square feet of new pavement and a new-and-improved drainage system to hopefully better direct water under the road and prevent future closures.
That’s good news for visitors like Brent Edwards of Beaver, Utah, who stood near a gate that’s currently blocking cars from accessing the road past the South Fork Picnic Area. It closed to vehicle traffic after the collapse in March and closed to foot traffic when construction began in September.
Edwards said hiking and camping around Kolob Canyons — which he describes as one of his favorite places on Earth — has been the source of many lasting memories for his family over the years.
“It's been a great experience. I can't wait till it opens again,” Edwards said.
This isn’t the first or last time erosion will close a road in southern Utah. In the same park bulletin that announced the Kolob Canyons Road closure, Zion informed visitors about a giant boulder that smashed part of Zion Canyon Scenic Drive and temporarily cut off power to Zion Lodge.
Tyler Knudsen, a senior geologist with the Utah Geological Survey in Cedar City, has seen landslides and rockfalls tear away at routes across the region. But some areas are more vulnerable than others.
“[Kolob Canyons] is a pretty precarious spot,” he said. “It's just a hard place to have a road.”
Kolob sits on a rock layer called the Kayenta Formation, which Knudsen said is relatively weak and prone to erosion. Similarly fragile layers of stone show up near SR-14 east of Cedar City, SR-12 near Bryce Canyon National Park and even Interstate 70 near the San Rafael Swell. In each of those spots, he said, erosion can create both beautiful rock formations and headaches for road maintenance crews.
The process can unfold particularly fast here on the Colorado Plateau, where high elevations and soft sandstone produce a recipe for erosion.
“It creates that hot-knife-through-butter effect where you get extremely high erosion rates,” Knudsen said.
Utah’s wet winter of early 2023 sped up the process, too. The extra moisture kept Knudsen’s team unusually busy documenting all the landslides throughout southern Utah.
He said it’s a glimpse into what the region’s future erosion dynamics may look like as climate change makes rainfall events less frequent but more intense.
“You can get these weaker soils that have less moisture. You couple that with increased intensity of the storms, and that's going to lead to increased erosion,” he said.
The Utah Geological Survey is currently creating a statewide geologic map so infrastructure engineers and residents alike can better understand where the hazards lie. For places his team has already mapped — including areas around St. George, Moab, Zion National Park, Bryce National Park and much of the Wasatch Front — you can zoom in to pinpoint where there are the highest risks for earthquakes, floods, landslides and expansive soils.
Tools like that could help parks and cities avoid erosion damage before it starts, he said, by knowing how to place new roads out of harm’s way. The best way to protect existing roads, he said, is to make sure their drainage systems can handle increasingly intense rainfall events — by installing larger culverts, for instance.
It’s important to remember that visitors can have an impact on these fragile places, too, Zion’s Shafer said. One tip is to resist the urge to park your car on unpaved shoulders along the park’s roads — something that can both contribute to erosion and harm native ecosystems.
“There are simple things that you can do to make sure that you are also contributing to Zion staying Zion,” he said. “One of the easiest is: make sure that you park on a paved spot.”
