PAGE, Ariz — One of the more popular attractions to see at Glen Canyon National Recreation Area has collapsed, officials said.
The Double Arch in Rock Creek Bay, also known as the “Toilet Bowl," “Crescent Pool,” and “Hole in the Roof," collapsed Thursday. It was often seen in photos and videos by people who travel up the lake.
The exact cause of the collapse was not revealed, although officials said that changing water levels and erosion from wave action is suspected.
"I think there's pretty good evidence that when you do have drawdown and water levels go down, I think it's common to have more rock fall and more instability along that shoreline," said Tyler Knudsen, senior geologist for the Utah Geological Survey. "As you know, because water levels come up the rock, that sandstone absorbs the water, then when water levels drop it actually increases the water pressure of the water in that rock as it tries to escape and equilibrate with that lower lake level."
According to the National Park Service, Double Arch was formed from 190-million-year-old Navajo sandstone that originated in the late Triassic to early Jurassic periods. Since its formation, the arch had withstood erosion from wind and rain.
While no one was injured in the collapse, Knudsen says it's still advisable to be cautious when visiting geological features like Double Arch, especially when visitation numbers to parks and recreation areas continually increase.
"A lot of times there's desert varnish, or that pantina that's on the cliffs that kind of rusts and it goes into a darker color," Knudsen added. "And then when the rocks fall off, it'll be a fresh white color, a different color. And it's quite obvious where rocks are falling off these cliffs."
Knudsen also says to be cautious of entering alcoves, as many of them are unstable.
The Utah Geological Survey along with the Park Service does regular geologic and hazard mapping across the state to show you which areas are hazardous for rockfall, landslide or flooding susceptibility. Users can go directly to the Utah Geological Survey's Hazards Portal to check specific areas and their hazard level.
“This event serves as a reminder of our responsibility and need to protect the mineral resources surrounding Lake Powell," said area superintendent Michelle Kerns. "These features have a life span that can be influenced or damaged by manmade interventions. While we don’t know what caused this collapse, we will continue to maintain our resource protection efforts on Lake Powell for future generations to enjoy."
