User:Cullen328/sandbox/Royal Arches

On August 6, a mountain guide working for the Yosemite Mountaineering School climbed in the area and saw nothing out of the ordinary. On August 20, the same guide discovered the crack. Park ranger Jesse McGahey reported that "the following week a climbing ranger and a geologist observed it firsthand and they could hear it cracking like a frozen lake that wasn’t consolidated". Park geologist Greg Stock and a climbing ranger examined the crack and "heard continuous creaking noises and witnessed many rock chips falling out of the crack". By september 7, the crack grown by 12 feet in length, and was wider.

Other popular climbing routes on the Royal Arches include Super Slide, Peruvian Flake West, Rhombus Wall, Serenity Crack and Sons of Yesterday.

Factors long known to trigger rockfall on steep cliffs include "precipitation, seismic activity and freezing conditions". Research conducted at the Royal Arches by scientists with the United States Geological Survey and the National Park Service analyzed the role of very hot weather on exfoliation. The researcers installed motion sensors in the crack behind a slab of granite on the Royal Arches that measures 19 meters tall, 4 meters wide, and 10 centimeters thick, and monitored the rock movement for 3-1/2"years. They learned that the crack could open up as much as nearly half an inch on unusually hot days. The researchers concluded that "Our data indicate that the warmest times of the day and year are particularly conducive to triggering rockfalls, and that cyclic thermal forcing may enhance the efficacy of other, more typical rockfall triggers."

In August, 2023, the National Park Service closed down climbing access on the west side of the Royal Arches "as a precautionary effort to reduce risk from rockfall". A section of a hiking trail was also closed, and a detour was established.