February 19, 2023 – Yosemite National Park provides some interesting information on the history of rockfalls in the park, and advise on how to best stay safe.

Rockfalls are a natural and dynamic geologic process involving the detachment and rapid downward movement of rock. Due to its steep, glacier-carved cliffs, Yosemite Valley experiences many rockfalls each year. Historical records indicate that more than 1,500 rockfalls have occurred in the park since 1857. Massive piles of "talus," or rock debris, at the base of Yosemite Valley's cliffs are reminders of these dramatic events. Rockfalls help to create the beautiful and changing scenery in Yosemite National Park, but they also present potential hazards.

Rockfall hazard zones occur throughout the park near any cliff faces. If you witness a rockfall from the Valley floor, quickly move away from the cliff toward the center of the Valley. If you are near the base of a cliff or talus slope when a rockfall occurs above, immediately seek shelter behind the largest nearby object. After rocks have stopped falling, move quickly away from the cliff toward the center of the Valley. Be aware that rockfalls are inherently unpredictable and may happen at any time. Pay attention to warning signs, stay off of closed trails, and, if unsure, keep away from the cliffs.

Remember that Yosemite is a wild place. Rockfall is the most powerful geologic agent acting today in Yosemite. The dramatic cliffs of Yosemite are constantly being shaped by this potent natural force.

Photo Credit: NPS Photo; Big Oak Flat Road near Yosemite Valley, April 1948.

Learn more about rockfalls in our website: www.nps.gov/yose/learn/nature/rockfall.htm

Source: Yosemite National Park