After Double Arch’s Loss, Nature Lovers Wonder If Other Arches Are At Risk

Nature lovers and national park fans mourned the loss of Utah’s famed Double Arch, also known as the “Toilet Bowl” earlier this month. The arch, located at Lake Powell in Glen Canyon National Recreation Area, was well-known as a cliff-jumping spot, with visitors jumping from the rim into the water below.

But some other things have been bubbling up for park visitors since the collapse — worry and wonder. Could other arches be at risk?

The answer? Maybe.

Can we protect them? Not really.

“Our mission is not to freeze time and preserve these structures exactly as they are,” Karen Garthwait, spokesperson for Arches and Canyonlands national parks, told The Associated Press. “Our mission is to preserve the natural processes that create these structures, which of course, is the same process that will eventually undo them as well.”

In other words, scientists are trying to avoid the unnatural shortening of the arches’ lifespans, but they’re not going to great lengths to try to extend their existence.

What Caused The Collapse?

Changing water levels in Lake Powell due to drought and climate change may have played a part in Double Arch’s collapse, the AP reported. The reservoir’s water levels have been declining since 2001, according to the National Park Service. Unsustainable water withdrawals have led to the decrease of Lake Powell’s water levels as well.

The other culprit? Heavy foot traffic. Though cliff jumping is banned at the recreation area, it wasn’t uncommon to see visitors climbing the arch and jumping into Lake Powell. Human activity has sped up erosion at other arches too, namely at Arches National Park. The park has made strides to limit human impact on the structures in recent decades.

“Some people have the sense that rock is strong and humans don’t affect it,” Jeff Moore, a geology and geophysics professor at the University of Utah, told the AP. Moore monitors arches at Arches National Park, as well as others throughout Utah. “When these kinds of collapses happen, it’s a reminder that arches are really fragile. Subtle changes can make a difference.”

As recently as the early 2000s, park goers would often walk atop some of the 2,000 arches at Arches National Park, even hanging on them for photo ops. A climber once scaled Delicate Arch, the most famous of the structures. The ascent left marks in the sandstone that, according to Garthwait, can still be seen today. In 2006, park officials reworded regulations to make clear that climbing arches is prohibited.

Which Arches Are At Risk?

Park staff regularly monitor arches to assess safety to visitors, as it isn’t easy for the layman to tell whether an arch is stable or not. These natural structures may appear sturdy from the outside, but their integrity could be compromised by internal cracks. Though people are no longer allowed to walk or climb on the arches, some of the park’s paths wind beneath them, and a crumbling rock structure could injure unsuspecting passersby.

Park staff have been concerned about a crack in the famous arch dubbed “North Window.” The crack runs the length of the arch, which stretches over a path where thousands of visitors pass daily or pose for photos. A crackmeter installed in November 2015 records fluctuations in the crack, which may help predict risk of falling rocks. Over the past few years, the measuring device has found the expected cyclical changes with temperature, but the fluctuations have been larger than anticipated.

Moore and his team are currently monitoring North Window, Owachomo Bridge at Bridges National Monument, as well as 16 other arches in Utah to see how vibrations and other factors impact the structures and to flag if any are at risk.

Tales Of Arches Past

Around 2:45 p.m. on Sept. 1, 1991, visitors reported hearing cracking and popping sounds at Landscape Arch. Parkgoer Michael Müller heard noises as he stood beneath the arch, and was able to capture a video of a large piece of the structure falling as he hiked behind it shortly afterwards. No one was reported injured in the incident.

In August 2008, Wall Arch famously collapsed overnight, leaving nothing but a pile of rubble behind. Campers in the area reported hearing what they thought to be thunder that night, but the skies had been clear. No one reported witnessing the rockfall, and no one was injured. The arch’s demise was only realized at daylight.

Most recently, Rainbow Arch fell sometime in 2018 at Arches National Park. The arch, which spanned just above the visitor’s center of the park, went unnoticed after it crumbled, as observation of the arch halted in 2017 after not much change was detected. A hiker was the first to report the arch’s absence in February 2018, according to the Salt Lake Tribune.

“The Ultimate Etch-A-Sketch”

Double Arch may have been worn by human feet and have had to combat climate change and changing water levels. But other types of natural erosion and gravity are also at play for Double Arch and Utah’s more than 6,000 other arches. Rain, ice and groundwater have eaten away at the sandstone curves for eons.

“It’s a bit like sucking on a mint or a candy cane,” the National Park Service website explains. “It slowly dissolves in your mouth but will usually break up into pieces before it’s completely gone.”

The rocks at Arches National Park are history laid out. Each layer of rock represents a time period, a different environment that existed once upon a time. It’s a “virtual layer cake of rock miles thick.”

According to the NPS:

“A band of limestone might indicate the presence of an inland sea complete with colorful reefs. A section of sandstone tells the story of wind-blown dunes from a time that was even drier than it is today. A layer of shale contains the relics of a swampy river floodplain ruled by dinosaurs and giant trees,” the NPS explains. “Taken together, these layers reveal a picture of planet Earth that is forever changing on a time scale, beyond human comprehension. As awesome as these previous worlds may have been, nature is the ultimate Etch-A-Sketch, periodically wiping away its old artistry in favor of new masterpieces just as astounding.”

So no, the NPS will not wrap the arches in plastic, as was once proposed in the 1940s to combat erosion. They will let them fall. What’s next for this landscape may be beyond our wildest imagination.

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