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Jorge
climber
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Topic Author's Original Post - Oct 3, 2006 - 07:17pm PT
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So, whose were they? I think Clevenger found them at the base...
So Peter H. I saw your earlier description of your milestone ascent and thought you might like to see what others had placed (on lead?)
G
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Roger Breedlove
climber
Cleveland Heights, Ohio
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George, were those placed by Bridwell on the second ascent?
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Jacob
Trad climber
yucky valley
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id climb on them!
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scuffy b
climber
The town that Nature forgot to hate
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Regarding the title, "...after the shift..."
I believe Peter said recently that the Hourglass has not actually
shifted, based on the relationship between the roof and the
bolt.
A couple years ago bobh described getting a nut or two stuck
in Lechlinski Flake. Greg Barnes weighed in with a story of
having a cam get stuck there, returning the next morning to
clean it easily with room to spare.
I think even Werner had a tale of placing a tube on the Hourglass
and finding it stuck and crumpled by the time he descended.
People talk of the seeming instability of the Hourglass, but
we have no idea of the solidity of the connection below the
talus. It's not resting on unconsolidated fill, after all.
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Ed Hartouni
Trad climber
Livermore, CA
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Nov 12, 2008 - 12:45am PT
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bump
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Wade Icey
Trad climber
www.alohashirtrescue.com
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Nov 12, 2008 - 03:02am PT
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thermodynamic expansion/contraction? heard tell of some such..
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Greg Barnes
climber
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Nov 12, 2008 - 11:11am PT
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Large flakes are definitely known to expand and contract over the day in Tuolumne. Grant said he's bootied several anchor setups from the Black Angel anchor over the decades, and that it's common to have anchor gear get stuck there. The base of Lechlinski Flake (start of Swinger) expands about a centimeter during the day, we found that out when replacing You Asked For It with Drew. Placed the anchor under the flake, and then just left it there since we were replacing bolts and rapping. Probably 4 hours later, the flake had expanded 1 cm and the largest cam (#1 camalot) was fixed. We came back the next morning when it was cool, and the cam came out no problem, since there was 1 cm extra space. The cam was slightly squished.
Also, we noticed another route where the flake expanded over a couple hours and nearly fixed a cam - the first pitch of Just Say No, which is basically a system of semi-detached flakes right of OZ on Drug Dome.
Don Reid has a big collection of squished nuts. I have a great example (looks like the nut is made of taffy and someone chewed it flat), but I'm not sure where it is - I got it out of the crack below South Crack, just sitting deep in the crack.
Of course, with the size and thickness of the Hourglass, those might have been earthquake related instead of thermal expansion related...
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BASE104
climber
An Oil Field
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Nov 12, 2008 - 11:23am PT
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Yeah, there is definitely some expansion/contraction. I have a 1/2 inch angle that I bootied out of a crack behind a really fat flake. The flake wasn't even very expando. It is flattened and split down the middle. I pulled it out with my fingers.
It is up on my office shelf with all of the other groovy stuff. The crack is about right for a 1/2 inch angle, but this one had been there for a while and was basically crushed flat. So remember when you are nailing that not everything fixed is perfect.
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Peter Haan
Trad climber
San Francisco, CA
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Nov 12, 2008 - 11:37am PT
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I like this subject. It keeps coming up in a variety of threads. Recent giant avalanches have made us all realize that even Yosemite can have bad rockfalls. In the 60's -70’s there were hardly any at all though, oddly. And with these big exfoliating slabs all over the place we do find that the cracks they create vary during the day, over the years and during quakes. And this thread is probably the best yet on the issue.
The Hourglass is about 400 ft tall above the talus, measuring on the taller left side. And it varies between 4 ft and 8 ft thick and between 50 ft wide and 120 ft depending on where you measure it. And it is completely detached from the wall at least above the talus and pedestals from which it emerges. Chockstones are distributed randomly behind it too.
Given these data there is probably someone here who could predict distortion of the thing (roughly of course) from thermal differences between the face of it and the cooler inner side. It stands to reason that this differential will produce planar changes (warpage), probably varying due to width and thickness and natural faults within it as well as the amount of temperature gradient.
As well, surely in earthquakes we will see movement, perhaps permanent changes even especially if chockstones slide down and wedge differently. And if a flake gets tons of ice and snow behind it in the winter we could have ice-wedging for months also. And if you look carefully at the Hourglass as a whole concern develops over the possibility that the upper section of it could snap off at a horizontal line about where the tree is; it’s kind of narrow there and there appear to be some faults there too.
But it is really eery, for sure. I had heard about these crushed pieces for many years. Thanks George. Vern Clevenger used to rave about them to me. Thanks for putting them up!
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TwistedCrank
climber
Ideeho-dee-do-dah-day
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Nov 12, 2008 - 11:58am PT
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Global warming has kept the flakes bigger longer. That's why they're all falling off nowadays.
Besides, mass wasting was heaps different in the 60s and 70s.
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Toker Villain
Big Wall climber
Toquerville, Utah
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Nov 12, 2008 - 02:24pm PT
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EDIT:
You mean like Woodstock?
There are two types of thermodynamic fluctuations; diurnal and annual.
Some cracks here get noticeably wider in the winter as the rock contracts.
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scuffy b
climber
On the dock in the dark
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Nov 12, 2008 - 05:47pm PT
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The cracks always seem tighter to me in December and January,
Ron.
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Toker Villain
Big Wall climber
Toquerville, Utah
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Nov 12, 2008 - 05:55pm PT
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That could happen too scuff if there is enough mobility to shift back and forth.
Part of the X factor is the shifting of the aforementioned chockstones too.
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Roger Breedlove
climber
Cleveland Heights, Ohio
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Nov 12, 2008 - 06:15pm PT
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I thought you were talking about Thanksgiving and Christmas calories.
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CF
climber
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Nov 12, 2008 - 08:11pm PT
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Don Reid found some at the base of HG years ago also.
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Dr.Sprock
Boulder climber
I'm James Brown, Bi-atch!
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cool beans on the measurements,
can we get some stress gauges in there after the deflection tests?
i would like to see what kind of forces these flakes are capable of generating,
you might want to anchor the flake in case the stress gauge ends up loosening the flake due to back pressure from the gauge,
have you had a class frtom mr ramsey, the lisping geologist?
"shhhissst sssssshlate and sshhherpinteine ssspeccimensss formed by extrusssssionss of loose denturesssss..."
oh sh#t, wrong thread,
please assoctate this threa with this link, which is how i eb=neded up screwing up in the first place, gee thanks scuffy,
http://www.supertopo.com/climbers-forum/1189611/Measuring-rock-flake-deformation
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