Lake Powell’s ‘Double Arch’ isn’t the first to collapse in Utah — and it won’t be the last, officials say

The sudden collapse of “Double Arch” over Lake Powell on Aug. 8 serves as a reminder that even stone is impermanent.

Officials aren’t quite sure what brought down the famous arch, formed from rock dating as far back as the Triassic or Jurassic period, according to the National Park Service. Also affectionately referred to as the “Toilet Bowl”, “Crescent Pool”, or “Hole in the Roof,” it once stood within Rock Creek Bay of Utah’s Glen Canyon National Recreation Area.

“The great thing about geology is that it happens extremely slowly — except for when it doesn’t,” said Karen Garthwait, a spokesperson for Arches and Canyonlands national parks.

Garthwait explained that naturally occurring arches like “Double Arch” likely collapse more often than we realize, given that Arches National Park has over 2,000 arches within its boundary alone, but they are not always so visible or popular.

These collapses, though sometimes shocking, are accepted and even appreciated by park officials.

“Arches National Park doesn’t protect arches. It preserves the natural processes that both make arches and eventually unmake arches,” said Garthwait, adding that the park’s mission “isn’t to stop time.”

That mission is what halted a proposal to stabilize the tenuously skinny leg of the park’s iconic “Delicate Arch” in the ‘40s, said Garthwait. Since then, arches have been allowed to stand or fall naturally.

Here are the most notable collapses from recent decades:

‘Landscape Arch’ loses a piece in 1991

“Landscape Arch” warned visitors of its fragility by first cracking and popping on the afternoon of Sept. 1, 1991.

A visitor by the name of Michael Müller was hiking nearby at the time. To investigate, he made his way up a slope behind the arch, where he managed to capture video of the rock fall, which he shared with the National Park Service.

He felt the earth shake as the stone fell. “For a moment I felt paralyzed,” he said in an October 1991 interview, according to a park service transcript. “Then I thought: Was there anyone underneath the arch like I was five minutes ago? Is there more material to fall?”

The arch lost a significant chuck of redrock but did not collapse. Thankfully, no one was injured.

Today, “Landscape Arch” is thinner but stubbornly stands. As a precaution, the trail under the arch is closed, said Garthwait.

‘Wall Arch’ crumbles in 2008

When “Wall Arch” fell, it sounded like thunder, said campers who were sleeping at Devil’s Garden Campground on Aug. 4, 2008, according to the National Park Service.

The sandstone arch was hefty, weighing thousands of pounds, but it was still unable to withstand the test of gravity and time.

Its once static rocks took flight, plummeting to the ground and sliding onto the Devil’s Garden hiking trail.

The fall of the once-12th largest arch in the park is an example that our eyes cannot detect the possible strength or weaknesses of these ancient structures.

When asked if it is possible to predict future collapses, Garthwait said, “you can’t tell from looking at them.”

‘Rainbow Arch’ falls unnoticed in the winter of 2018

The most recent notable collapse was the fall of “Rainbow Arch” in 2018. The arch, which was located just above the visitor center of Arches National Park, had recently been under observation by a research team from the University of Utah.

They had noticed a crack through its center and were expecting some decay. However, after a year of observation that yielded no change, they decided the arch was stable.

They stopped monitoring the arch in 2017 before its absence was noticed by a hiker in February of 2018.

Arches have both “power” and “fragility,” said Garthwait. They might evolve by falling, and each change makes a space for something new.