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CCT
Trad climber
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Anyone know how long it takes lichen to colonize fresh granite? Look at this photo - lichen above the exfoliation zone, no lichen below. So, the split can't be older than a hundred years or so, right?
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mongrel
Trad climber
Truckee, CA
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Yeah, le_bruce, that's a nice looking splitter there, but I'm not that sorry the 5.9 squeeze is gone. I recall it as not being very fun with a lot of rack. Why I didn't have just a couple pieces and no aiders, just stupid I guess, but it wasn't a very fun pitch up top. And I usually like chimneys and wide just fine.
It's too bad the bivy is gone. It was good, with nice separate spots for two, and not stinky when we did it because you only end up there if you start super late or walked up that morning. Rocks falling from high up fall right over you, a little ways out in space (this happened, or maybe a body).
The Wombat is certainly right, the next chimney pitch or two are next, and not that far in the future, I'd wager. Some future year, a famous ledge higher. It'll be known as Thank-God-I-Wasn't-On-It Ledge.
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PellucidWombat
Mountain climber
Berkeley, CA
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Easily some of the best pitches I've ever climbed - you too?
Yep! Makes me sad I might not ever get a chance to do them again.
I'm not that sorry the 5.9 squeeze is gone
It looks like its still there. It just lost the 5.7 beginning and a floor to cap the bottom :-)
In a more vertical and rocky sense, the flake collapse seems like it could be similar to a glide avalanche, with the flakes on the N Face almost positioned like these slabs, ready to go as soon as meltwater debonds them enough from the slabs.
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F10
Trad climber
Bishop
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Time to chain Boot Flake to the wall before it goes.........
Maybe not, I've heard it has been missing on several April 1st, but is still there !!
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limpingcrab
Trad climber
the middle of CA
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I like that I always read info here firsthand and then see it the next day on the climbing magazine sites.
Go supertopo!
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Kalimon
Social climber
Ridgway, CO
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Don't take anything for granite . . . impermanence is the rule.
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ElGreco
Mountain climber
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Wait, wait. le_bruce implicated again?? The dude was the one who filmed the massive May 2011 rockfall!
http://www.supertopo.com/climbers-forum/1516671/Half-Dome-Death-slabs-rock-fall-5-27-11-video
I sense some kind of self-destructive fetish here whereby he climbs the juicy splitters to exhaustion and then stuffs them with dynamite.
I was on this thing on Jun21. The recent chit chat on the beta page about rockfall made me uneasy. Sleeping at the base and being on the Slabs was not exactly carefree - let's put it that way. On the day of the climb, we saw two blocks come down in sequence. We were traversing up and right towards the Robbins bolt ladder at the time. Not sure if they were from the visor or lower down.
People mention rockfall in relation to this face all the time. Is it really that active? Or do we just read about the eventful ascents but never know about the 100s that don't witness any rockfall because... there's nothing to write about?
I find it astounding that on a long Jul4 weekend, and with the spring running, no one was on a trade route like this or on the Slabs. Did the thunderstorm chances put people off? Whatever the reason, let's be thankful (if indeed no one was on/near it and we won't hear about a missing party in the next day or two - I sincerely hope not).
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Kalimon
Social climber
Ridgway, CO
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Bring a bolt kit . . . everywhere!
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Edge
Trad climber
Betwixt and Between Nederland & Boulder, CO
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When the last layer of the RNWF falls waste from the Half Onion, then the route I climbed will be no more, it will be as if I climbed 5 feet out from the new face, levitating up memories.
I find that fascinating.
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Steve Grossman
Trad climber
Seattle, WA
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When I first did the RNWF in the 70s, I stopped a pitch below Big Sandy and was looking around for the usual fixed pin anchors. I finally found them and they were hidden behind a flake that had moved diagonally such that you could no longer pound on the pitons as they were originally placed. I leaned out and followed a 30 degree rising fracture line as far as I could see in the outside plate that forms Big Sandy so it is moving too!
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big wall paul
Trad climber
tahoe, CA
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So it the regular nw face classic shut down?
This is the first big shut down since Hockey Night in Canada lost two pitches 8 years ago. anyone remember that episode? Lot of talus created there. I'll have to ask cragnshag about this. He probly doesn't care since he's too busy doing first ascents in the Valley on lesser known cliffs.
I figure everybody and their mom must be heading up the death slabs to establish the new connection for P10-12. If I didn't have wife and two young kids, that's where I'd be heading.
Paul.
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tripmind
Boulder climber
San Diego
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I'd bet that all the sh#t and piss that has filled all the big cracks at the major ledges have seeped down and started weathering the attachment points of these types of flakes, causing it to separate over time. Poop tube enforcement soon.
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TomCochrane
Trad climber
Santa Cruz Mountains and Monterey Bay
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Added to my list: Direct North Face Lower Cathedral Rock (with Kor), El Cap Tree Direct (with Sacherer), major rock fall past us on El Cap Nose while we were on Dolt Tower in 1985 (from the Grey Bands? with Claire Mearnz), Seneca Gendarme, North Face Middle Teton, North Face Mt Temple (with Margaret Young and Jim Richardson), major rock fall from near summit of Grand Teton North Face while I was soloing it in 1963, a few others I've previously listed on ST...the mountains are alive...
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steveA
Trad climber
Wolfeboro, NH
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I bet the Direct NWF will become more popular. I assume the rock is more stable than the regular route. I feel it could be done by a fast party in a day, but it took us 2 days, back in 1972.
It is a beautiful line.
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gstock
climber
Yosemite Valley
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Brandon Latham and I scoped this (literally) yesterday afternoon. I don't have a lot to add actually, beyond what's already been posted here, but here is some additional information, some of it speculative:
The rockfall occurred affected pitches 11 and 12 of the Regular Route on the Northwest Face (see image below, rockfall source area shown in red). The failure consisted of a relatively thin, triangular-shaped rock sheet at least 60+ meters (200+ feet) on the longest side. The thickness of the sheet varied from about 1-3 meters (3-9 feet), suggesting an approximate volume of roughly 800 cubic meters.
The lack of direct observation strongly suggests that the rockfall occurred at night. Thunderstorms occurred on the night of July 2 and the early morning of July 3, dropping 1.8 cm (0.72 inches) of rain in less than 24 hours in Yosemite Valley, and probably more at Half Dome; when I observed Half Dome early on Friday morning water was still streaming off of it. Most likely the rockfall occurred just after the peak of precipitation early on the morning of Friday, July 3. The inclement weather probably accounts for why it appears that no climbers were present. I was listening for rockfalls during the storm, but it may be that it sounded like one of the many thunderclaps that night.
More information about the condition of the route can be found on the Yosemite Climbing Information website: http://www.climbingyosemite.com
Mark, your idea for the failure mechanism has merit. I tend not to think of the stresses as P-Delta forces, but the basic idea of slab buckling is valid, and in fact you can see such buckled slabs in many places in Yosemite on lower-angle terrain. The puzzle always is to figure out why the failure occurred at that exact moment. My colleague at the USGS (a civil engineer) and I have been pursuing different ideas about thermal stress triggering, and have documented rather large diurnal movements of a flake near Royal Arches due to temperature fluctuations. In this case I suspect that water was also involved, but it makes sense to me that hot summer temperatures would cause daily cyclic deformations that propagate cracks into the remaining solid rock ("rock bridges"), and then a final shot of water into the cracks elevates cleft pressures and off it goes.
And yes, by its very exfoliated nature the Northwest Face is prone to rockfalls. The database of Yosemite rockfalls (http://pubs.usgs.gov/ds/746/); shows 8 documented rockfalls from the Northwest Face since 2006, but I'm sure that many more occurred that were not documented. Intriguingly, there are no documented rockfalls from the Northwest Face in winter. This may simply be due to under-reporting during this time of the year, but it could also relate to the thermal stresses that I mentioned above, as the Northwest Face gets direct sun only during the late spring and summer.
I've posted this before, but this quote by Galen Rowell about the Northwest Face seems especially relevant now. Could he have been writing about the area that just fell?
"Several hundred feet above the base, the narrow crack in which we were inserting pitons widended. It became a chimney, large enough to crawl inside. At either side of the back wall of the chimney there was a three-inch crack, continuing out of sight for hundreds of feet overhead. The back wall was eight feet behind the present surface, parallel to the main cliff. The cracks completely separated it from the outer rock, on which I was climbing. Here was the northwest face of the future, fully cleaved and waiting patiently, be it one or one hundred thousand years until it gleams for a geological moment in the noonday sun."
Greg Stock
Park Geologist
(209) 379-1420
greg_stock@nps.gov
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BLUEBLOCR
Social climber
joshua tree
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^^^Thank You GStock.
That Rowell quote is gnarly!
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bbbeans
Trad climber
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wowowowowowowowowowowowow.......... That is an amazing quote Dr. Stock. Thank you for your analysis!
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pyro
Big Wall climber
Calabasas
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Bring a bolt kit . . . everywhere!
100%
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Jason A Graves
Trad climber
Carlsbad, CA Anchoredman.com
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Trying to look on the bright side... maybe the11c corner and 5.7 splitter leading up into the chimneys will have a much more exposed and classic feel to them now?
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