Discussion Topic |
|
This thread has been locked |
gstock
climber
Yosemite Valley
|
|
|
Topic Author's Reply - May 15, 2012 - 08:33pm PT
|
Update: Contrary to my post above, the instrumentation is still in place as of spring 2012. We decided to keep the instrumentation going for another summer to be able to fully evaluate the effects of non-reversible deformation over the course of a full year, and also to make some acoustic measurements of possible crack growth on the hottest days. We now intend to take the instruments down this fall (fall of 2012).
Thanks again for your support of this interesting project - it is proving to be influential among the international community of scientists studying rockfalls.
Greg
|
|
nutjob
Gym climber
Berkeley, CA
|
|
|
May 15, 2012 - 08:54pm PT
|
So if there is a rattly fingers flake that I want to make an easier thin hands, just wait until afternoon. And if it's a little too wide to get a knee lock, just try it again the next mid-morning. Excellent.
|
|
Steve Grossman
Trad climber
Seattle, WA
|
|
|
May 15, 2012 - 09:14pm PT
|
It would be interesting to put a Crack-o-meter in the Hollow Flake.
Tom Frost is convinced that one is getting wider and it is arguably the longest flake system in the Valley. It would be interesting to see what the cycles would look on this test case.
|
|
dfinnecy
Social climber
'stralia
|
|
|
May 15, 2012 - 11:36pm PT
|
This is cool, is there a description somewhere of how the crackmeters work?
|
|
kaholatingtong
Trad climber
the green triangle, cali
|
|
|
May 16, 2012 - 12:29am PT
|
yes, i believe it is a few posts up. very interesting study.
|
|
Jan
Mountain climber
Okinawa, Japan
|
|
|
May 16, 2012 - 01:25am PT
|
Very interesting. Thanks.
|
|
Steve Grossman
Trad climber
Seattle, WA
|
|
|
May 19, 2012 - 01:28pm PT
|
Crack-O-Bump...
|
|
Spider Savage
Mountain climber
The shaggy fringe of Los Angeles
|
|
|
May 19, 2012 - 01:52pm PT
|
I once placed a hex in a flake on Tahquitz granite first thing in the morning. About 15 minutes later, my partner tried to remove it after the sun hit the flake. A good experienced climber he was. No way was that thing coming out.
Later that day the placement was back in the shade and I climbed up and pulled it, no problem.
The change in width was amazing. After that experience I am amazed that these granite cliffs don't rain exfoliation every day.
|
|
crunch
Social climber
CO
|
|
|
May 19, 2012 - 03:24pm PT
|
East face of Echo Tower, in the Fisher Towers, Utah.
Jumaring past the lower, steepest section, 15 feet out from the rock, with no nearby, visible cracks, each morning there would be occasional, random, loud, deep, thumpy, "crack!" noises; presumably from the sun quickly warming the face after a cold night. We figured that there were/are exfoliation cracks hidden inside to separate the insides (with a more consistent temperature) from the surface (with wildly fluctuating temps). No moisture involved, no ice.
This face is low down, overhanging, with a vast weight of stone (several hundred vertical feet) above. Must be all under enormous stress and will one day all collapse.
East face of Kingfisher, near start of Death of American Democracy, similar noises can be heard as the sun warms the rock in the early morning, though the rock is merely vertical.
Geology in action!
Never heard spontaneous cracking noises from the rock anywhere else, ever.
|
|
|
SuperTopo on the Web
|
Let us know!