An iconic geologic feature collapsed recently, the well-known Double Arch in Utah’s Glen Canyon National Recreation Area. Made of 190 million-year-old fine-grain Navajo sandstone, the arch formed between the late Triassic and early Jurassic periods and collapsed on August 8, according to the National Park Service. Other names for the Double Arch include the Toilet Bowl (rude!), the Crescent Pool and the Hole in the Roof, because the double arch formed what appeared to be a ring.
A video on social media showed swimmers at Lake Powell distressed by falling rocks, and one commenter wrote, “The arch at Lake Powell collapsed yesterday. It stood for 190 million years and fell on our watch.” Although it's the sandstone itself and not the arch that has been there for 190 million years, the comment still represents how shocking and sad the loss is. The National Park Service reports that it does not know why the arch collapsed, stating that “Changing water levels and erosion from wave action is suspected of contributing to the ultimate collapse of the arch.” Since motorboats are permitted on Lake Powell, perhaps that has something to do with the erosion from wave action—and certainly, the changing water levels can be traced to humans due to the climate emergency.
Thankfully, no one was injured as giant chunks of the sandstone fell off into the water below.
According to Glen Canyon National Recreation Area Superintendent Michelle Kerns, the surprising incident should remind us of “our responsibility and need to protect the mineral resources surrounding Lake Powell. These features have a life span that can be influenced or damaged by manmade interventions.”
Let’s hope that another spectacular feature in the same national recreation area stays upright: the Rainbow Bridge, one of the world's largest known natural bridges—also made of Navajo sandstone.
Editor's note: This article has been updated for clarity.