A Rockslide In Yosemite Is Common

So what causes a rock to break away? Several things. Earthquakes, large storms and the freezing and thawing of water in the granite joints are the most common of reasons. Rock falls are a natural consequence of the continuous exfoliation process that occurs on these granite cliffs.

I was hiking Vernal Falls when one of the largers rock falls took place in Yosemite. It was in 1987 and it was scary. It was very loud. When you are hiking on a trail, there is no where to run when huge bolders come running down the mountain. Two days after we left in July 1996 another huge rockslide happened. It did quite the number on Happy Isles.

October 2008 saw a rockslide that brought down 6,000 cubic meters of rock. Closing all of Curry Village for 2009.

519 rockfalls were recorded in Yosemite from 1857 to 2004. Those were just the big ones. Small rock falls often go unrecorded. Of the 519 recorded rockfalls, 330 of them were in the valley itself. So they don't just happen in the higher Sierra Nevada Mountain Range.

Do people get injured in Yosemite rock slides? Absolutely. Some even die. When these rocks break away they are sometimes falling from over a mile high. They have been recorded to reach speeds of 174 mph. When tons of granite fall, plums of grey smoke fill the valley air. The rock is pulverized when it hits the valley floor. Hundreds of trees can be broken in a matter of minutes. Rock slides have been going on for at least the last 17,000 years here in Yosemite.

It pretty easy to see where rock breaks off of a cliff. There will be a lighter patch of granite that looks smoother than the rest of the mountain. I have heard it said that, "Mother nature owns this park." And I think they are right.

Watch A Video Of It Happening

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