
Glacier Point 1996,-USGS photo
We stood on a high overlook above Yosemite Valley and squinted, attempting to see down into the valley or across to the opposite ridge.
All we could see was a thick fog of dust, masking the resting place of the thundering torrent of rocks that had given way just a few minutes before.
It was July 10, 1996, and my husband Nic and I had just come up from Mariposa Grove in Yosemite National Park, where we’d completed the six-mile hike to Wawona Point and back. When we heard the rumble—louder than thunder, punctuated by sharp cracks and echoing throughout that section of the Sierra Mountains—we pulled into the first overlook we found. From the opposing ridge near Glacier Point, a 300 to 400 foot slab of granite had given way and tumbled down 2,000-plus feet into the valley below, sending some 162,000 tons of rock to a new resting place on solid ground.
When it hit a cliff ledge, the granite slab shattered, its chunks pulverizing one another on their way to the valley floor. The resulting dust settled at its leisure throughout the next three days, covering picnic tables and campsites directly below with fine, gray powder six inches deep.
Later we would hear that a 20-year-old man died in the landslide, and a hundred-yard swath of 500 trees went down as the weight of thousands of tons of granite swept over them. A snack shop near Happy Isles in the valley was nearly crushed, but remarkably, the rest of the damage was slight.
When we drove into the park from our hotel in Merced the next morning, however, a less natural phenomenon appeared. Lined up along the main road, live remote trucks with satellite antennae on their roofs bustled with activity, their rear or side panels flung open. Reporters in epaulet shirts and khakis—and in some cases, high heels—held microphones into the faces of park officials. We spotted the logos of all three broadcast networks and CNN as the media searched for the story’s most dramatic piece, working to determine if somehow, in some unrevealed way, the park was to blame.
Geologists studying the area over the last several years have discovered a series of cracks along the cliff faces, perhaps caused by pressure from water flowing beneath the surface. Trees that find precarious footing on these rock faces may also contribute to the rock’s tenuous integrity in this area, by sending their roots into the cracks and prying the stone apart.
Sure enough, on October 9, 2008, another landslide sent granite crashing to the valley floor in Curry Village, a lodging and camping area surrounded by Yosemite’s astonishing cliffs. No one perished in this year’s rock fall, but three visitors received treatment for minor injuries, and several cabins suffered partial damage.
In every national park around the world, natural forces continue to work—many of them in silence, giving us little or no warning of the next startling event. While we may not leap to camp in Curry Village on our next trip to Yosemite, it’s these physical demonstrations of the awesome power of nature that lure us back to the parks every year, in every season—and nature’s unpredictability, good or bad, lends adventure to every trip.











Comments
Here is a hyperlink to a complete geologic report on the 2003 and 2007 Staircase Falls rockfalls above Curry Village in Yosemite Valley.
http://www.nat-hazards-earth-syst-sci.net/8/421/2008/nhess-8-421-2008.html
This is in a slightly different location than the (current) October 8, 2008 rockfall. This comprehensive geologic report will keep readers informed of the complicated and dangerous field work that is currently underway by geologists with the US National Park Service (Dr. Greg Stock), and the US Geological Survey (Dr. Gerald Wieczorek). These geologists deserve our heartfelt gratitude and support.
Robert H. Sydnor
Engineering Geologist
Fair Oaks, California
RHSydnor@aol.com
Thank you, RobertI will follow up on this for a column in the near future.
Randi
The granite at Yosemite is very young, geologically. It's still settling in after millions of years. The exfoliation process continues and results in these kind of breaks. What to do? Wear a helmet to bed at Curry!
Rick Deutsch-Mr. Half Dome
"One Best Hike: Yosemite's Half Dome"
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