I had hiked about 100 yards on the Upper Yosemite Fall trail when I heard a rare but identifiable sound. I stopped and stood as still as possible to drown out the ambient noise and to focus on rocks colliding and bouncing through the wooded area beyond the trail to my right. I could not see the rockfall nor any dust from its downward tumble. Plus, the steep canyon walls surrounding Yosemite Falls echoed the sound of the bouncing boulders against the rock faces, making it hard to locate exactly where the loosened granite traveled.
Of course, I had no intention of outrunning the rockfall even if I could identify its location. A rock slide is not the kind of event you can prepare for like a weather forecast, as if you could equip yourself with a helmet or umbrella to protect you against falling stone. Rockslides start unexpectedly and once gravity has wrung them of their force, they end. I simply wanted to know where it started, where it was going, and when it would end. Then, I could determine if I should continue hiking to the top of Yosemite Fall or call it quits due to the ongoing dangers of another slide. After about 20 seconds, the sound of the cascading boulders faded, and quietness prevailed. It was 6:45 in the morning.
I determined that the boulders fell southeast of where I stood, and came to rest somewhere in the forest slope beyond the trail. Because rockfalls tend to occur in clusters, however, I wanted to be cautious about continuing. Since I seemed to be going in the opposite direction of the rockfall, I decided to hike upward on the switchbacks above me, while being alert to any additional risks. With a quickened pace, I met up with two other hikers who confirmed that they too heard the rockslide in the same location as I did. Like me, they deemed that the risks in continuing were light.
The slide would likely be described as “extremely small” by US Geological Society (USGS) standards. For me, however, it was still a rockslide, and records indicate that the area surrounding Lower and Upper Yosemite Falls experiences rockslides of all sizes regularly.
The great rockslide of 1996 that sent a huge slab of granite down Glacier Point’s north-facing wall, and whose subsequent air blast leveled hundreds of trees, continued to drop rock and debris from the fracture for the following two days. A friend of mine who camped at Upper Pines Campground when that slide occurred, shared great detail of that colossal event, and it remains fresh in my mind after all these years.
Also, in two days from now, I had planned to hike to Sierra Point, a trail that has not been maintained by the National Park Service in over 40 years due to rock falls claiming the trail. The trail to Sierra Point continues to draw intrepid hikers, however, as a destination due to its unique location. The view from Sierra Point allows the observer to see five different waterfalls from the same spot (e.g., Upper Yosemite, Lower Yosemite, Vernal, Nevada, and Ilillouette Falls), the only place in the Park where that is possible.
According to Waymarking.com, Sierra Point also claims recognition for being a spot where 14-year-old Ansel Adams took some of his first photos from an old Brownie camera that his father gave him during a summer visit to Yosemite in 1916.
Although the hike to Sierra Point trail includes some of the steepest terrain of any “trail” in Yosemite, and “scrambling” over rocks and boulders best describes the work needed to reach it, it is less than a mile to the viewpoint. The steep topography and the rainy and icy winter weather contribute to Sierra Point being prone to rockslides.
A United States Geological Society (USGS) report that compiled a history of rockslides in Yosemite National Park indicates that the trail officially closed in 1967 when a rockslide knocked out stone steps on a portion of the trail that included cables to ascend a steep granite rock face. Several other slides occurred in the 1970s. Then, a significant rockfall occurred in May 1980 when a magnitude 6.1 earthquake, centered in the Mammoth Lakes area (about 43 miles from Yosemite), shook the Sierras. Massive boulders careened down from the ridge between Sierra Point and Grizzly Peak, stopping just before meeting the Mist Trail to Vernal Fall. The USGS Report quotes Gilliam (1982) saying that “on the main Vernal Fall trail near Happy Isles, is the 60-ton boulder that cut a swath through the trees as it bounded down from the point in the May earthquake."
Jim Snyder, the well-known Yosemite historian, adds that the “slide destroyed 70% of the Sierra Point Trail, seriously injuring two people.”
Currently, the slide area can be identified by a sign that stands at the non-river side of the Mist Trail, about a hundred yards beyond the Happy Isle Trail marker. In big letters, the words “Rock Pile” highlight the theme of the educational message showing the impact of the compact car-sized boulders that litter the area where the Sierra Point trail once started.
The rockslide I heard while starting my hike to the top of Upper Yosemite Fall gave me plenty of things to think about along the way, not the least of which being the history of rockfalls at Sierra Point!
After reaching the top of Yosemite Fall, I continued onward about a mile more to Yosemite Point (elevation 6,936 feet (2,114 meters)). There, I enjoyed another grand, wide-angle views of Yosemite’s famed Valley as I looked out over the guardrail. Of course, I noted to myself that I made it to this Point without being hampered by any more rockslides. As I looked to my left to the vicinity of Sierra Point, the only place in the Park where five waterfalls can be viewed, I hoped that my trek there would be free of rockslides too.
Stay tuned for my rockslide report next month in Part 2 of “Seeking Sierra Point.”
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