Grack aea rockfall danger?? Is it Overstated??

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Brokedownclimber

Trad climber
Douglas, WY
Topic Author's Original Post - Apr 15, 2011 - 01:12pm PT
I'm in the early planning stages of a trip (again!) to the Valley sometime later in the year; not sure when. I've always enjoyed several of the fine routes on the Grack (Center, and Marginal) and on Monday Morning Slab (i.e. Harry Daley, Chouinard Crack, etc.), and would really like to have a shot at Mister Natural and the Apron Jam.

A non-local sometimes doesn't have sufficient information whether to simply avoid the entire GP Apron, of if there are selective "safe zones."

Any advice from the Super Topo peanut gallery?
murcy

Gym climber
sanfrancisco
Apr 15, 2011 - 01:19pm PT
Did you see the latest comment on the beta page?

http://www.supertopo.com/rock-climbing/beta/Yosemite-Valley-Glacier-Point-Apron-The-Grack-Center

Do you feel lucky?
Ed Hartouni

Trad climber
Livermore, CA
Apr 15, 2011 - 01:54pm PT
the entire Valley is falling down... some rather impressive slabs have fallen of recently with no one around to see it happen, though in climbing areas where routes have been erased and in view from major tourista turnouts...

you roll the dice... and lucky for you you usually win...

a couple of years ago I was over climbing Apron Jam... on the way to Mr. Natural where a party doing the same a while back met with tragedy.

Climbed all the routes you've mentioned over the years many times since the rock fall...

Point is your number could be up whenever you touch any of those cliffs... danger overstated? probably not, but it is not confined to just the Apron...

JEleazarian

Trad climber
Fresno CA
Apr 15, 2011 - 02:23pm PT
Ed speaks truth, as usual. I would only add that both the Grack and the Monday Morning Slab areas or on minor ridges that tend to deflect small rockfall to either side. Not true for Apron Jam or Mr. Natural, which also have some obviously loose sections high above. Other than that, you take your chances whenever you climb. While the objective danger is not trivial, neither is it close to what exists on so many serious Alpine routes.

John
Karl Baba

Trad climber
Yosemite, Ca
Apr 15, 2011 - 02:29pm PT
Mr. Natural area probably has more likely rockfall, followed by the Grack, with everything inbetween being safer.

I'd climb in all those places although springtime is more dangerous as freeze thaw cycles are active and water is flowing through cracks and stuff

Peace

Karl
bergbryce

Mountain climber
Oakland
Apr 15, 2011 - 02:40pm PT
A friend of mine claims to have had a rockfall experience on the Apron this spring and has stated he is not going back. He's kind of a beginner so maybe he's blown it out of proportion, but his story sounded pretty damn' scary. I believe he was on the Grack.
Ed Hartouni

Trad climber
Livermore, CA
Apr 15, 2011 - 02:47pm PT
[attempt at levity, answer to a mysterious question, slight offtopic twist]

Why do we climbers describe the size of rockfall in terms of kitchen appliances?

"microwave size block"

"refrigerator size..."

etc...
Clint Cummins

Trad climber
SF Bay area, CA
Apr 15, 2011 - 02:51pm PT
> Did you see the latest comment on the beta page?

They didn't state where the rockfall occurred, relative to their location on the Grack. I haven't seen any impact marks on the Grack routes.
There is increased rockfall hazard to the left of the Cow/Grack (where there is a big blast zone), for pretty much anything left of Tightrope.
There is also a hazard on Hall of Mirrors - there is fresh talus at the base from a rockfall in early 2009. It is a natural drainage path.
I would feel fine doing the Grack anytime in settled weather.
I wouldn't climb on the higher risk areas if there is any snow on the rim.

The other bad zone is right of Green Dragon.
I wouldn't climb The Punch Bowl until the talus on the ledge above it clears out; will take many years.
TomCochrane

Trad climber
Santa Cruz Mountains and Monterey Bay
Apr 15, 2011 - 04:37pm PT
Go climb the North Face of the Grand Teton and then come back and see if these questions are still worrying you about the Apron. Not to mention the North Faces of Edith Cavell or the Eiger...

Come to think of it, the biggest rock fall I've ever experienced came down all around us while sitting on top of Dolt Tower on the Nose.
Brokedownclimber

Trad climber
Douglas, WY
Topic Author's Reply - Apr 15, 2011 - 05:25pm PT
Well, the lower East face of Long's Peak isn't any slouch either. I recall some big stuff coming down while I was on Stettner's Ledges.

This was a general topic question, since not too many Tacos seem to climb on the Apron anymore... Cragman had some comments at Flandersfest, thet the Grack in in a safer zone than most of the Apron.
Ed Hartouni

Trad climber
Livermore, CA
Apr 15, 2011 - 05:28pm PT
people that climb there don't think it is any different then anywhere else, I think... and people who don't climb there don't
Clint Cummins

Trad climber
SF Bay area, CA
Apr 15, 2011 - 06:26pm PT
Jim,

>> springtime is more dangerous as freeze thaw cycles are active and water is flowing through cracks and stuff - Karl Baba

> I've heard this many times and it seems to make sense. But is it true?

You can download the spreadsheet (1857-2003) and test it statistically if you want:

http://pubs.usgs.gov/of/2003/of03-491/of03-491.xls

and the report:

http://pubs.usgs.gov/of/2003/of03-491/of03-491.pdf

Just looking, there are definitely a lot in the spring. Also winter.
I could do the stat test and make some graphs, if somebody is interested.

P.S. Have fun in the Valley this weekend.
gstock

climber
Yosemite Valley
Apr 15, 2011 - 06:50pm PT
Here are a few relevant graphics. The first is a map that shows rock falls in Yosemite Valley (1857-early 2011) for which a relatively precise location and season of occurrance are known.

The second image shows rock falls (as a percentage of the total 1857-2007) as a function of precipitation and temperature in Yosemite Valley. This plot excludes rock falls triggered by earthquakes.

You can see that March and April are generally the peak months for the number of rock falls. However, this plot does not include volume data, and there are some very large rock falls that occur in the summer.

Greg

Greg Stock
Park Geologist
Yosemite National Park
(209) 379-1420
greg_stock@nps.gov
Ihateplastic

Trad climber
It ain't El Cap, Oregon
Apr 15, 2011 - 06:56pm PT
I was with some elder statesmen on Coonyard last September. As you might know, this takes off from the top of Monday Morning. This was the FIRST TIME EVER that I wore a helmet in the Valley.

While we experienced no rockfall I will say (since I was doing the leading) that Coonyard's typical slip-slide greasiness was multiplied by a fine layer of dust on every edge and over the entire slab. Now, keeping in mind that each winter the Apron gets plastered with snow and ice, this dust is probably there simply because the Apron has fallen out of favor and there was no one ahead of us in X amount of time to dust things off, but all the same it made me wonder if this was the best place to be.

I, too, convinced myself that the natural ridge-like nature above Monday Morning meant I was in safer territory but in reality I have to imagine that when bowling balls start tumbling down from above they go wherever they want; ridge or no ridge.
Clint Cummins

Trad climber
SF Bay area, CA
Apr 15, 2011 - 06:58pm PT
Thanks, Greg - nice graphics!
To me, they suggest that rockfall (in terms of number of occurrences) is spread out fairly uniformly across the year.
So the freeze/thaw/wet is not that dominant; things can also move by thermal expansion / contraction in sunny times.
WBraun

climber
Apr 15, 2011 - 07:00pm PT
I don't care what graphs exist nor what anyone says. But that's just me.

I never go to the apron area unless there's a body to retrieve and those bodies are not pretty.

That whole place over there gives me the willys as I witnessed too much of all that stuff coming down.



Brokedownclimber

Trad climber
Douglas, WY
Topic Author's Reply - Apr 15, 2011 - 07:13pm PT
I'm not sure that I'll be doing anything at the Apron this fall, after these comments. I never have liked rockfall, but have seen plenty of it.

So...as the bottom line, there really isn't any "safe zone" there.
rick d

climber
ol pueblo, az
Apr 15, 2011 - 07:17pm PT
jeremy- are those photos of you spilling a tall boy?

at least sandstone you can live through being hit with a 2 ton block. Granite will grind you into cheese...
StahlBro

Trad climber
San Diego, CA
Apr 15, 2011 - 07:23pm PT
I didn't have too many issues on the Apron (except water activated)
I had a pretty horrendous experience at the base of El Cap (La Esquela sp?)
I finally realized why no plants grow at the base. We left all the gear and tried to hide under the scruffy little oaks. I watched as the one next to me (the same size as the one I tunneled under) was obliterated.

I ran for my life to largest pine I could find after about 15 min of continous bombardment. I watched a front door sized flake about a foot thick "flutter" like a dropped piece of paper out over the valley, then back toward the face. It did this 2-3 times making sound affects like the helicopters in Apocolypse Now. When it finally reached the trees the sound of destruction was mind blowing.

The Germans that were climbing next to us said they were going back to camp to get their helmets. I laughed hysterically and told them that all that would be left was a helmet with a pair of Fires sticking out of the bottom.

After that I went to the Meadows for the next 4 years until my stones grew back. I just had to dodge lightning up there.
WBraun

climber
Apr 15, 2011 - 07:26pm PT
Now ain't that the truth ^^^^

Seeing rocks come down on top of you will surely cause the most seasoned hard man to piss in his pants .....
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