Zion trail closures caused by same geology that made the canyon, not by human impact

Virgin River, Zion National Park, date not specified | St. George News

ST. GEORGE — Trail closures at Zion National Park, one of the most popular parks in the country, can leave visitors disappointed. But the very forces that created the park are also what is driving the closures, officials say.

The line forming at the Grotto to hike Angels Landing was hours long over Memorial Day weekend, Zion National Park, May 25, 2019 | File photo courtesy of Zion National Park, St. George News

More than 318 million people flocked to national parks across the U.S. in 2018, the highest number of park visitors in recorded history. More than 4.3 million of those visitors went to Zion, making it the fourth most popular park in the United States.

Zion is currently experiencing four trail closures, the Upper Emerald Pools Trail, Hidden Canyon, Observation Point and part of the Kayenta trail. Oftentimes, the damages that cause these trail closures are assumed to be caused by human impacts.

However, the closures may have little to do with the rise in visitor numbers and may not be human-caused at all, according to a National Park Service statement.

In fact, it is the same dynamic geology that attracts so many visitors to the park that is the driving force behind the closures, they said. And even though Zion’s geology appears to be “stable and unchanging,” the exact opposite is true.

The water erosion that sculpted the park is still constantly at play in a dynamic, ever-changing cycle. This cycle often causes rocks to break off from the sides of the canyon, causing a rockfall.

Loose, falling rock can be very destructive, particularly to the trails running throughout that park, requiring extensive maintenance, rehabilitation and repair. In some cases, a new trail is designed and constructed around the rockfall when the damage to the existing trail is so severe that it destroys a particular section of it.

Zion officials recommend planning ahead by visiting the current conditions page on their website to know which trails are closed before visiting the park.

Zion National Park — 240 million years in the making 

Zion makes up part of the Colorado Plateau, where rock layers have been uplifted, tilted and eroded, ultimately forming what is known as the Grand Staircase. The staircase is a series of colorful cliffs stretching between Bryce Canyon National Park and the Grand Canyon.

About 240 million years ago, Zion was a relatively flat basin near sea level. But as the land rose and fell, sand blew in and deposited about 10,000 feet of material, according to NPS.

From there, mineral-laden waters slowly filtered through the compacted sediments, acting as cementing agents. With pressure from overlying layers over the course of time, the material was transformed into stone. This transformation gave the streams greater cutting force as they made their way to the ocean, eroding and cutting into the rock layers and forming the park’s deep and narrow canyons.  The geological makeup of the park leaves it vulnerable to flooding, falling rocks and unstable soil and erosion.

Copyright St. George News, SaintGeorgeUtah.com LLC, 2019, all rights reserved.

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