Rockslide on Highway 140 Near Yosemite (Video)

Headed up to Yosemite Valley today to see some waterfalls and enjoy the holiday. Had a wonderful time, but had an extra surprise. Got to see a modest rockslide on Highway 140 on our way there, and managed to catch it on video! We were driving down Highway 140 near Midpines on our way down to the Merced River when the new rockslide caught my attention. A lot of rock had already fallen, and given that there was a bulldozer parked on the other side, it was clear that the main event had happened a day or two earlier, but I decided I wanted a picture so we stopped and I hopped out.
As I approached the slide, I could see a couple of large boulders still perched near the top of the roadcut that looked unstable, and I could hear small pebbles bouncing down the slope. When I got closer, I realized the pebbles and cobbles were dropping out from under the larger boulders. The rock was slowly giving way and I had a suspicion (and yes, a secret hope) that it might be about to collapse. I moved the camera setting to video, and only a minute later I got lucky. I was standing across the highway, and luckily no cars were passing at the moment. A couple of the broken chunks landed on the highway

The picture above is the only shot I got before the slide. The rocks on the lower part of the roadcut are probably greenstones, metamorphic volcanic rock, while the unstable material above is metamorphic slate. Both are part of the late Paleozoic Calaveras Complex or Sullivan Terrane. The material was deeply weathered (thus the red coloration), which contributed to the slope instability. Further instability was introduced by having a roadcut in the first place, which oversteepened the slope, and by the tremendous amount of precipitation we've had this year, around 150% of normal. There were numerous other examples of recent slope failures along the entire Highway from Mariposa to the entrance of Yosemite National Park.


Sure, it wasn't the biggest slide in the world, but it was very loud, and it was very cool to be standing in front of it when it happened. You can hear me starting to say "I'm O.K." at the end of the recording, mainly because my wife was down the road a bit and heard the rocks drop, but couldn't see me.

The way it was today: Yosemite Valley

My field studies course took in Yosemite Valley and the Merced River today; we had about 18 students, at least four of whom had never been to Yosemite before. It was a beautiful day in a sense, but challenging for photography; it was overcast and gray, and all the colors were muted. Even worse, the contrast between land and sky was almost impossible to compensate for. I've had to either remove color entirely (black and white) or saturate the colors almost beyond the reality of the day. Our first stop was the famous tunnel view. The parking lot was nicely renovated, but the view is much as it always has been: spectacular! Half Dome was hidden in the clouds.

I calculated recently that I have been to Yosemite Valley at least sixty times in the last twenty years, yet I never tire of the place. When you have seen the iconic domes and cliffs and waterfalls this many times, you may find your eyes wandering from the familiar outlines, and looking for the unfamiliar; I was captured by the cloudy mist flowing down a section of the Rockslides, a slope ignored by most people at the Tunnel View.

There are cliffs at Yosemite Valley which seen in isolation would merit attention at any other place in the world, maybe gaining some special status as a park or monument. Here, these spectacular cliffs have a name, but I had to look it up: the right-hand cliff is Stanford Point.

Bridalveil Fall plummets 620 feet over a sheer cliff. This classic glacial hanging valley is famous enough to merit a crowded parking lot and trail, but I found myself drawn to the huge cliffs that surround it. The high tower in the background is one of the Cathedral Rocks.

The valley today was on the cusp of a spring eruption. Green shoots are just beginning to show in the meadows, but the winter snows still cling to the high country. The waterfalls are flowing, but nowhere near the discharges that will be here in early May. We've come through three tough drought years, but this year the precipitation was almost normal, aided in part by El Nino conditions in the Pacific Ocean. It won't be enough to fill the half-empty reservoirs but the soil water may be replenished enough that more trees will be able to resist when the pine beetles attack...