Middle Cathedral Rock-Fall 3/16/2013!

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BASE104

Social climber

An Oil Field

Mar 20, 2013 - 04:24pm PT

Greg,

You could do a totally non-invasive 3D seismic survey of the entire valley. Now the geophones are wireless and the energy source could be vibraseis on the roads.

I've never seen a 3D shoot of anything like this, especially with the velocity problems that you will get with talus, which could be large. Weathered zones such as any alluvial deposits are really tough to correlate. It would be interesting.

In the meantime, yep, El Cap has huge talus depostits on both sides of the Nose. If you have ever humped the approach all the way to the W Buttress, you have to go uphill a long way.

Things that are above sea level are always heading downstream and downhill. I would love to work on the stratigraphy of the glacial and alluvial deposits in Yosemite.

gstock

climber

Yosemite Valley

Mar 20, 2013 - 05:17pm PT

Base, I would love to do that, especially since the only previous seismic investigations of Yosemite Valley occurred in the 1930's (published in 1956): http://gsabulletin.gsapubs.org/content/67/8/1051

My efforts to fund such a study have thus far been unsuccessful.

Clint Cummins

Trad climber

SF Bay area, CA

Mar 20, 2013 - 06:04pm PT

those pictures of the Middle Cathedral rockfall made me wonder if Thirsty Spire or The Turret are still attached.

They're definitely still there and not coming off anytime soon.
If one of them came off, the road would be blocked.

A good reference for comparison are the July/September 2011 rockfalls which came off the North Face, slightly left of Mother Earth.
They generated a lot of dust and deposited a lot of small rocks/gravel all along the base when the source flakes disintegrated on the way down.
But Greg's photos pinpointed the sources as some relatively small flakes.
http://www.supertopo.com/climbing/thread.php?topic_id=1552021

In the 90s I was at the base of El Cap and saw a very similar (to 3/2013) rockfall come down the North Buttress of Middle, with lots of dust. It was sobering, because we were planning to do the route in the next day or two. We made other plans. :-)

In the late 80s I saw some boxcar sized blocks come down the middle of the North Face from the band of overhangs up high. Big impact craters at the base.

The height from which the rocks fall in the Valley is another dimension to the rockfall risk (besides frequency and volume).
It leads to devastation at the base!

Largo

Sport climber

The Big Wide Open Face

Mar 20, 2013 - 06:09pm PT

I'm amazed that Middle doesn't just fall over some time. It was always my favorite rock by I cut back my time on the big faces there after Billy Westbay got beaned one time when we were on the DNB and Kauk and I almost got cleaned off Stoner's by a big ass rock slide from the U-Shaped Bowl. We were down low and I rapped off the rope to the ground and just took off running, right off the end of the line as sh#t continued raining down.

JL

Bruce Morris

Social climber

Belmont, California

Mar 20, 2013 - 07:07pm PT

Sometimes Middle around Stoner's is as quite as a mouse. Sometimes a couple of basketballs come down there without any warning. Just keeps you on your toes. But then there's that north apron area . . . big stuff waiting to happen.

Norwegian

Trad climber

the tip of god's middle finger

Mar 20, 2013 - 07:13pm PT

is it really just a sloppy interaction
between gravity and the adhesive / cohesive
forces of the mountain's resolve?

perhaps there are mountain gnomes
than can come and go from our plane
as they please; and these gnomes,
they've personalities and tempers
and sex and suicide, just like us.

perhaps if you pay proper homage to
the mountain prince, rockfall aint gonna
gather in your path?

perhaps if you mastrabate twice in the
bush directly below their blow hole,
they can be adequately please of your
enlightened passage?

im trying it next go.
good thing i aint partners,
and i go solo on these
awkward understandings.

KabalaArch

Trad climber

Starlite, California

Mar 20, 2013 - 07:26pm PT

I - that is: "Willy and I": - have had quite a few footballs and toasters sail past us on the MCR Apron over the years. It's very important to remain focused when these UFO's come hooting past 'yer run.

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.

You don't have to be Matthes to realize that, some day, the entire Valley shall be refilled into the vee-shaped river gorge whence it came; I've seen some of the geotech's maps of the max talus outfall zones, which seem to exclude only Sentinel Beach - and scarcely so, at that.

Question on point seems to be: is this going to occur before Tioga opens this season?

TomCochrane

Trad climber

Santa Cruz Mountains and Monterey Bay

Mar 28, 2013 - 12:45am PT

One day in the mid 1960's, Jim Mays returned to Camp 4 on his old bicycle with wide eyes and rock dust in his hair. He came up to my camp by the Wine Boulder and told about riding down the road towards El Capitan past Rixon's Pinnacle, when boulders the size of semi-trucks started bounding down across the road all around him. Some rather large pot holes were punched into the road and some boulders blocked the road for a while. We walked back there together and he showed me the fresh rock fall boulders.

I've mentioned earlier about experiencing a major rock fall coming down all around us on Dolt Tower in 1985.

Another day in the early 1960s I walked from Camp 4 up to the base of the Nose of El Cap early in the morning after a big ice storm. When the sun hit the upper face, large sheets of ice started melting and falling down directly towards me, fluttering around like heavy falling maple leaves. On either side of me there were great slabs of ice crashing into the forest. Those that came directly down the nose were pulverized by impact with the rock and reached me as a shimmering curtain of ice crystals in the sunlight.

I've spent many days on Glacier Point Apron and on the Cathedral Rocks without any recollection of rock fall.

gstock

climber

Yosemite Valley

Jun 10, 2014 - 05:55am PT

Heads up that there was a rockfall from Middle Cathedral on Sunday morning, June 8, 2014. Several "car-sized" boulders fell from near the top of the Direct North Buttress. Debris swept the DNB and areas to the east, almost as far east as the Central Pillar of Frenzy.

mikeyschaefer

climber

Yosemite

Jun 10, 2014 - 11:19am PT

Any photos of the suspected release zone Greg?

gstock

climber

Yosemite Valley

Jun 10, 2014 - 11:30am PT

A climber who witnessed the rockfall from the first pitch of the Nose sketched it out like this:

I haven't yet been able to pin down an exact source area.