Yosemite Rockfalls

NEWSThe park has positively identified the body of Ramina Badal, 21 year old, of Manteca, CA. Her body was found in the Merced River, approximately 120 yards below the Vernal Fall footbridge. She was one of the 3 people who went over July 19. All  bodies have now been recovered.

Rockfalls are a fact of life at Yosemite.  You’d think that the tens of thousands of year since the glaciers, that all loose rocks would have fallen by now. Actually the glacier cuts caused the cliff sides to be unstable, contributing to breaking loose. Rockfalls can occur when rain water gets into cracks then freezes. When water freezes it expands. The small but constant expansion takes its toll and the granite may open slightly. Lichens can grow here and when they die they provide a soil structure for larger plant seeds to germinate. In time, the growing plant exerts forces that can lead to a flaking off. Given enough time, these processes can take their toll. A major rockfall occurred in the 1980’s off of the Three Brothers formation. In 1996 and again in 1999, enormous sheets of granite dropped near Happy Isles, each killing one person. They produced massive shock waves that literally snapped thousands of trees. The 1996 rockfall was comprised of two slabs (totaling 80,000 tons) bigger than 2 football fields and three stories tall. They free-fell 1800 feet and reached an estimated velocity of 270 miles per hour when they impacted. In October 2008, two falls (a day apart) off of the Glacier Point wall behind Curry Village took over 200 units out of service. You can still see the rubble fields from these falls. These events are unpredictable, but they are a reminder that Yosemite is undergoing constant change.  In 2009, an even larger rockfall than the 1996 Glacier Point fall occurred at Ahwiyah Point near the eastern side of Half Dome’s face. An estimated 115 tons of rock crashed down onto the southern portion of the Mirror Lake Loop Trail. If you are on top of Half Dome you can carefully crawl out to the edge and look down at the fresh white stone talus field.

In the last 150 years there have been 15 deaths attributed to rockfalls.

To learn more, I recommend watching the nine-minute video about rockfalls in Yosemite (part of the Yosemite Nature Notes video podcast). It includes some amazing eyewitness footage of the 2009 rockfall behind the Ahwahnee.

Medical Minute:  6 weeks after my stunt of getting off a HARLEY at 30 mph, I was allowed to stop wearing my left leg brace and I don’t need to use a crutch anymore. I began rehab today. 2 weeks of isometric exercise then I can pick it up a bit. Could be 6 months until I’m back at my hiking form. Plenty of time for Half Dome.  Collarbone has never hurt…but the 8 broken ribs are still angry.

 

Unrelated thought worth quoting: When I’m watchin’ my TV and a man comes on and tells me how  white my shirts can be. But he can’t be a man ’cause he doesn’t smoke the same cigarettes  as me. I can’t get no – satisfaction.” – the Rolling Stones

 

*MrHalfDome™ – Rick Deutsch – www.HikeHalfDome.com

One Best Hike: Yosemite’s Half Dome

About Mr Half Dome - Rick Deutsch

Mr Half Dome. Has written the only half dome hiking guide, One Best Hike: Yosemite's Half Dome. Has hiked it 31 times to day. Lives in San Jose, CA Available for presentations. Carpe Diem Experience, LLC
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