Discussion Topic |
|
This thread has been locked |
Vitaliy M.
Mountain climber
San Francisco
|
|
|
Topic Author's Original Post - Mar 18, 2013 - 10:30pm PT
|
Did anyone else see it? Knows anything about it?
Happened mid day. Just left of the water streaks which split the formation in half. Was very loud and had a lot of stuff coming down. I got my camera out just after majority of it passed..
|
|
pell
Trad climber
Sunnyvale
|
|
|
Mar 18, 2013 - 10:39pm PT
|
We were approaching El Cap base. I did a couple shots.
Seems it was not too far from DNB.
It happened around 10:45am.
|
|
cleo
Social climber
the canyon below the Ditch!!!!
|
|
|
Mar 18, 2013 - 11:36pm PT
|
Make sure gstock gets a good report!
|
|
le_bruce
climber
Oakland, CA
|
|
|
Mar 18, 2013 - 11:42pm PT
|
From 3 pitches up. Looked like it came down right over the North Buttress route. Loud for sure, but maybe not huge in terms of material released? Good reminder, in any case, of the many ways that we all spin the roulette wheel day in and day out in life.
|
|
donini
Trad climber
Ouray, Colorado
|
|
|
Mar 18, 2013 - 11:56pm PT
|
Vitaliy....shore those cliffs up, i want some climbing left when i get there in May.
|
|
GDavis
Social climber
SOL CAL
|
|
|
Mar 19, 2013 - 12:36am PT
|
quick, check the base for new bad ass talus bouldering!!!!! If it is so good in RMNP there has to be some awesome blocks sitting at the base waiting for your radness***, and probably still warm, too!
|
|
Clint Cummins
Trad climber
SF Bay area, CA
|
|
|
Mar 19, 2013 - 10:49pm PT
|
Yes, it looks like it came down the North Buttress.
|
|
Adamame
climber
Santa Cruz
|
|
|
Mar 19, 2013 - 10:51pm PT
|
Looks pretty small compared to some of the rockfalls in that are from past years. Good thing there are raptor closures over there right now.
|
|
survival
Big Wall climber
Terrapin Station
|
|
|
Mar 20, 2013 - 12:21am PT
|
Good thing I wuz waring muh helmet and muh shouldamuhpads. Oh, and my cup.
|
|
Fat Dad
Trad climber
Los Angeles, CA
|
|
|
Mar 20, 2013 - 12:24am PT
|
Some 30 yrs. ago, I was on the East Butt. of MCR and some rockfall came down the Spires gully. The volume and cacaphony was just crazy. Still very vivid all these years later.
|
|
TomCochrane
Trad climber
Santa Cruz Mountains and Monterey Bay
|
|
|
Mar 20, 2013 - 12:34am PT
|
the biggest rockfall i've ever experienced seemed like a few of tons of boulders crashing around past us while sitting on top of Dolt Tower in 1985
|
|
limpingcrab
Trad climber
the middle of CA
|
|
|
Mar 20, 2013 - 12:54am PT
|
Who's gonna get the FA of that new tan spot!?!
|
|
lucander
Trad climber
Shawangunks, New York
|
|
|
Mar 20, 2013 - 01:49am PT
|
I heard that the guy who has been chipping in the Gunks has been in California.
|
|
Sierra Ledge Rat
Mountain climber
Old and Broken Down in Appalachia
|
|
|
Mar 20, 2013 - 02:51am PT
|
Yes, it looks like it came down the North Buttress.
1+
Looks like a direct hit
Wonder how the route changed
|
|
gstock
climber
Yosemite Valley
|
|
|
Mar 20, 2013 - 03:30pm PT
|
Thanks for the report and great photos. There have been many rockfalls from Middle Cathedral in the past two years. Happily I've already ticked the North Buttress!
A couple of years ago we measured talus volumes beneath several of the major cliffs in the Valley, and then normalized the volumes by the size of the cliff above it. This allows us to directly compare long-term rockfall activity from the different cliffs over the past 15,000 years or so. The results, listed in terms of more rockfall to less rockfall are:
1. El Capitan (Salathe Wall)
2. Cathedral Rocks
3. Middle Brother
4. Glacier Point
5. Royal Arches
Interesting that Glacier Point, which has a reputation for rockfall, actually has had fewer rockfalls (or at least smaller rockfalls) over time than El Capitan. This highlights how much our individual experience colors our perception of hazard and risk. We evaluated this pattern with respect to many different variables and found the best correlation with degree of glaciation - basically, the cliffs that were extensively glaciated have had fewer rockfalls, most likely because the fractured, weathered rock in those areas was cleaned off by glacial erosion.
Greg Stock
Park Geologist
greg_stock@nps.gov
(209) 379-1420
|
|
Clint Cummins
Trad climber
SF Bay area, CA
|
|
|
Mar 20, 2013 - 03:37pm PT
|
I'm surprised about the result for the Salathe' Wall. Do you really mean El Cap Gully and face over to Ribbon Falls (left of the West Face of El Cap) as the source of the talus field? I am thinking the big slope under El Cap Gully / West Face / SW Face is different rock (e.g. KP Pinnacle) from El Cap itself (say West Face). I'm thinking this different granite mix type collapsed a long time ago. Vs. continually fell off of El Cap right until the present.
I'm not sure if that normalization for "rockfall activity rate" works so well for Glacier Point, because about half of its height is a very smooth slab that should not produce any major rockfall. The upper half, with the trees, etc. should be where the rockralls come from. And when they come down, they won't be slowed down much by barriers on the slab!
[Edit:] Thanks for the extended answers, Greg!
There are a few different rates which could be calculated, due to the dimensions like frequency over time, volume, etc.
For example, the huge rockfall event out of the NA Wall:
 huge on the volume scale
maybe small on the frequency of time scale
I guess we climbers may perceive risk on the frequency over time scale, for volumes large enough to kill us.
Is there a way to use the size of unforested talus slopes as an indicator of active rockfall areas?
How would the huge unstable talus slope under Nuts Only Cliff figure on your activity rate scale?
|
|
gstock
climber
Yosemite Valley
|
|
|
Mar 20, 2013 - 03:54pm PT
|
Clint, our calculation was for just the talus underneath the Salathe Wall proper, exclusive of debris that came from KP Gully or from the Ribbon Falls area. It surprised me too, but look at the size of that talus pile!
One big unknown though is exactly where the bedrock is under the talus. We investigated this at Glacier Point with geophysics (seismic, resistivity, and ground-penetrating radar) and found that the talus there was sitting on river sediment. But we haven't done that at El Capitan, so it's possible that the volume is large because some of it is bedrock.
Regarding Glacier Point, you are correct that the Apron has had very few rockfalls (there is still glacial polish there). However, even when we exclude the lower portion of the cliff area below the glacial trimline, the adjusted rate is still somewhat lower than El Capitan.
The problem with the talus of the Rockslides area (Nuts Only Cliff) is that it was downvalley of the maximum extent of recent glaciation, so it has been accumulating for much longer.
Greg
|
|
Clint Cummins
Trad climber
SF Bay area, CA
|
|
|
Mar 20, 2013 - 04:04pm PT
|
It's cool that there are still many basic unknowns like the bedrock level under the slope below the SW Face of El Cap.
The slope still doesn't look like an "active rockfall slope" to me because of the trees. More like a "historic rockfall slope"?
Perhaps it's my bias to the time dimension here again.
|
|
JEleazarian
Trad climber
Fresno CA
|
|
|
Mar 20, 2013 - 04:15pm PT
|
Clint,
I remember heading up toward La Escuela in the early 1970's, and the base of the southwest face of El Cap looked like someone had bombed it. I believe that particular rockfall was from a couple of pitches of the Heart Route.
I am rather surprised that the Three Brothers, and particularly the east side of Lower and Middle brother, are not higher on the list. The area to the left (southwest) of Rixon's Pinnacle has always been known as a bowling alley, and I remember rockfall around The Folly that added another Bear Rock sized boulder or two to the talus field.
In any case, those pictures of the Middle Cathedral rockfall made me wonder if Thirsty Spire or The Turret are still attached. Ever since Sentinel Spire bit (or, more accurately created) the dust, I've always wondered about last ascent possibilities.
John
Edit: Checking Greg's reference to the thread on the Heart Route confirmed that the rockfall came from that route. Apparently, the white tower (aka Tower to the People) and some associated pitches simply fell off.
|
|
|
SuperTopo on the Web
|
Let us know!