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gstock
climber
Yosemite Valley
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The Columbia Boulder has an exposure age of about 4,400 years. Dated boulders within the greater Camp 4 area (beneath eastern Middle Brother and the Camp 4 Wall) range from about 700 years old to about 10,300 years old. Again, we were only able to date a small portion of the total number of boulders. Some boulders beneath the main part of Middle Brother came down in rock falls in 1987 and 2000.
The white streak on the talus behind the Ahwahnee results from the 2009-2010 Rhombus Wall rock falls. We wrote about those rock falls here: http://www.nps.gov/yose/naturescience/upload/Stock-et-al-2012-ESPL.pdf
If you look at historic photos (late 1800's) of Yosemite Valley you can see a lot of similar fresh talus that has now grown over. In other words, rock-fall activity shifts throughout the valley, and places that do not look active now are not immune to future rock falls. The 1996 Happy Isles rock fall is a good example, as that event blew down some of the largest and oldest trees in the valley.
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Les
Trad climber
Bahston
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This all smells very fishy to me.
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Mighty Hiker
climber
Vancouver, B.C.
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The NPS will make the decisions it must, based on the best information and analysis available. In the case of Camp 4, climbers should simply say that a) it should not lead to any reduction in the area of the campground, b) it should not lead to any reduction in the number of campsites, and c) it should be generally consistent with Camp 4's NHR and cultural status.
Bear in mind that this may be temporary. Once the planning process concludes, there may be changes to Camp 4 that climbers will agree with and indeed be involved in. Sometime by around 2030, maybe...
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gstock
climber
Yosemite Valley
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I'll just stick to the facts here:
The boulders are dated using concentrations of the isotope beryllium-10. Beryllium-10 is produced in quartz when struck by high-energy cosmic rays. The rate of production varies with altitude and latitude but is well known. The key aspect for exposure dating is that this production only occurs in the top 2-3 feet of the Earth’s surface, so rock deeper than that (say inside a cliff) is not accumulating beryllium-10. Once a large rock fall occurs, there is a good chance (5 in 6 for a cube-shaped boulder) that the top of the boulder wasn’t exposed prior to the rock fall, and therefore the beryllium-10 in quartz is a measure of how long the boulder has been sitting there. I’ve written more about the technique, and discussed some of the potential pitfalls, here:
http://www.nps.gov/yose/naturescience/upload/rock-fall-el-cap-stock-uhrhammer.pdf
There is precious little information on boulders beneath the floor of Yosemite Valley, and no way to consistently incorporate this information. So we only used boulders that we could actually see on the surface. Given that some of these boulders are quite old I would be surprised if there are many more boulders beneath the surface, but again we don’t really know. If more boulders exist in the subsurface, then the reported hazard line would be a minimum estimate of the stated hazard.
Regarding relocation, the intent is to replace all eight high-risk campsites by December 1 within the greater Camp 4 footprint. Some of the alternatives of the new Merced River Plan call for expanded camping at Camp 4, both to the east near Swan Slab and across the road west of Yosemite Lodge; if you favor expansion of Camp 4, I encourage you to share that comment during the next public comment period.
I guess another fact I could share is that I've been climbing since 1989 and consider it to be an important part of who I am (ok, perhaps somewhat subjective). Two days ago I had the pleasure of climbing Holdless Horror with my 7-year-old daughter, who complained about it being too easy.
Greg
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Don Paul
Big Wall climber
Colombia, South America
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Some of the alternatives of the new Merced River Plan call for expanded camping at Camp 4, both to the east near Swan Slab and across the road west of Yosemite Lodge; if you favor expansion of Camp 4, I encourage you to share that comment during the next public comment period.
Thanks Greg this is something very positive to work on. Anyone interested in the Camp 4 modification, write a comment during the NPS notice and comment period. I'll bet that shrinking real estate is a bigger concern than the exact historical boundaries. Expand Camp 4 but in a different direction. Perfect. However I still advise getting that injunction in place before December 1. It's the difference between begging, and demanding your rights.
Anyway, what is the point of cramming all the climbers into the smallest space possible? We like camp 4 because it is a memorable part of the dirtbag experience. But to everyone else it must be an eyesore.
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Afterseven
Trad climber
Nome, AK
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Greg, Could you explain how the Glacier Point probabilities relate to the Camp 4 probabilities. Given that I note you show both the Glacier Point Map and the Camp 4 map; and also you show what happened at Glacier Point in a dramatic cautionary photo, as if the same risk sets exist at both locations?
While experts can disagree on the effects of human activity proximate to the cliffs edge and it's affect on rockfall...There simply isn't that kind of activity going on above Camp 4. I think its fair to say that substantial human activity at the top of a cliff raises the probability of rockfall below relative to those areas without substantial human activity at the top. Ultimately, was the quantity and quality of human activity at the top of the cliffs analyzed in drawing up your risk maps?
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gstock
climber
Yosemite Valley
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The hazard line everywhere represents the same level of hazard, i.e., a 10% chance of exceedance in 50 years. So the line at Curry Village and below Glacier Point represent the same hazard level. Historical rock falls were not quantitatively accounted for in the hazard assessment because a few decades (or even 150 years) is not an adequately representative period of time. Think if earthquake hazard assessment in the Bay Area were conducted only based on what had happened historically, rather than by systematically mapping faults, determining their rupture histories, measuring strain rates, etc., all of which allow for creating probability-based assessments. I understand that people feel that rock falls are rare at Camp 4 because they have not happened historically, but that relatively short period of time is just not a reliable indicator of the potential for future activity.
Regarding human activity at Glacier Point, there is no compelling evidence to suggest that activities at the top of the cliff have contributed to rock falls there. Many of you are familiar with the lawsuit associated with a climber fatality at Glacier Point in 1999. That lawsuit was dismissed in 2010 without delving into the science behind the allegations. We have subsequently analyzed the hypotheses that human water systems contributed to rock falls at Glacier Point and found those hypotheses to be highly unlikely:
http://www.nps.gov/yose/naturescience/upload/stock-et-al-2012-isl-NASL-Glacier-Point.pdf
Please note that there is a typo in the introduction of this paper: It should read "...between 1857 and 2011" rather than "...between 1957 and 2011".
Greg
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Bullwinkle
Boulder climber
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The Native American Sweat Lodge is much closer to an active rock fall zone, is the NPS going to downsize this area too? Or is that outside, of your imaginary line?
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Toker Villain
Big Wall climber
Toquerville, Utah
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Wasn't it the NPS that gave the OK for the firefall?
But you know better now?
Maybe people should just sign waivers at the entrance booths.
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gstock
climber
Yosemite Valley
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Jul 17, 2012 - 11:38am PT
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For anyone especially interested in this topic, I'll be giving a public presentation on the rock fall study next week in Yosemite Valley:
Special Yosemite Science Forum: Rock-fall hazard and risk assessment for Yosemite Valley
Tuesday, July 24, from noon to 1 pm in the Yosemite Valley Auditorium
The National Park Service, in collaboration with the U.S. Geological Survey and other academic researchers, recently completed a comprehensive rock-fall hazard and risk assessment for Yosemite Valley. Join Park Geologist Greg Stock for a presentation of the scientific methods used to derive a rock-fall hazard line, the results of risk analyses of structures and campsites, and actions proposed by the National Park Service to reduce this risk.
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Peter Haan
Trad climber
San Francisco, CA
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Jul 17, 2012 - 11:54am PT
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Greg,
How much did this study cost? When was it ordered? Where did the order for the study originate?
Thanks.
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Patrick Oliver
Boulder climber
Fruita, Colorado
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Jul 17, 2012 - 12:37pm PT
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When Tom Frost was preparing all his papers for getting
Camp 4 on the National Register and all that, he brought me
everything to rewrite, proof, and prepare. This was a lot of
stuff over quite a number of days. He worked very hard on all
that. I haven't talked with him for a spell, but I wonder if
he or anyone has begun any sort of effort to deal with these
new Camp 4 plans (or if it's even a real question that it
might be necessary). Greg, have you spoken with Tom? I'm sure
his thoughts would be interesting.
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Don Paul
Big Wall climber
Colombia, South America
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Jul 17, 2012 - 12:42pm PT
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It seems to be a reaction to the boulder that landed on the building in Curry Village, the photo of which was posted here before. I hope Tom Frost can get involved in this - why waste all that time getting camp 4 registered as a historic site if you're not going to defend it when its under threat?
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Peter Haan
Trad climber
San Francisco, CA
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Jul 17, 2012 - 01:06pm PT
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It has been the hope of the AAC and many many climbers worldwide that the original eighty site-size of C4 be restored. In fact it is somehow chartered I have been lead to understand. And it has been a decade apparently that we have been told this return to that status was in the offing. By moving sites closer together per this geo report should not necessarily affect the larger plan to have our original eighty sites; but one does wonder....
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k-man
Gym climber
SCruz
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Jul 17, 2012 - 01:27pm PT
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I'd like to see a climbers' camp in the vicinity of the old El Cap parking lot.....
+1
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klk
Trad climber
cali
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Jul 17, 2012 - 02:51pm PT
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I've met Greg and I've read his work. He is a serious guy who is active and publishing in professional scholarly circles outside of NPS. All of his published work is careful and cautious.
And he's a climber. We are fortunate that he's the expert on the point. Moreover, since any rockfall that does happen may well generate a lawsuit, each post he makes in this forum is something that might show up in court. If all he wanted to do was cover his ass, he wouldn't be posting in this and the various other threads about rockfall in the Valley.
While I understand the mistrust many climbers have for the NPS generally, accusing him of scientific fraud is just ridiculous. It's an incendiary charge, and it's not a charge one ought to make without real competence in the field and some compelling evidence.
The last thing ST needs is to become such a freak show that folks with genuine technical competence avoid the place.
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Elcapinyoazz
Social climber
Joshua Tree
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Jul 17, 2012 - 02:58pm PT
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While I understand the mistrust many climbers have for the NPS generally, accusing him of scientific fraud is just ridiculous. It's an incendiary charge, and it's not a charge one ought to make without real competence in the field and some compelling evidence.
Agree 100% and I am definitely one of those who mistrust NPS and have an exceptionally low opinion of their organization, work, priorities, stewardship, or usefulness in general.
Making reckless accustations against a scientist who does useful and honest work, and who seems to studiously avoid the political side of things is ridiculous and shameful.
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Don Paul
Big Wall climber
Colombia, South America
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Jul 17, 2012 - 03:12pm PT
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Peter, I agree, this could easily be turned into something positive. I have already outlined above how to put a stop to it with an injunction. Once the climbers show that they can stop the project, the NPS will listen to them.
I think that the study overestimates the danger. The danger of being crushed in your tent by a 10 foot boulder is not great. Actually, a six inch boulder would probably kill you too; this makes me wonder how the original premises of this project were determined. I think the 10 foot boulder was arbitrarily chosen, or maybe chosen to be the size of the one that hit the curry village building.
The real risk could be estimated by reviewing the last 50 years, or whatever, of campsite rockfall and the injuries/deaths that resulted. I'll bet there are VERY few examples. If injuries and deaths really were the issue, then instead of moving campsites, we'd be putting up fences on all the cliffs to prevent tourists from getting too close, totally enclosing the half dome cables route, and so on, taming the wilderness to make it a safe tourist attraction.
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