GeoRock
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Location: Mammoth Lakes, CA
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Nomad experiences Yosemite Rock Falls!
I could barely contain my excitement when I heard a rockfall begin October 7, Tuesday afternoon. My geologist ears immediately identified the
cracking, smashing, crashing LOUD sounds as a stair-stepping, falling down granite slab.
Sure enough, a huge dust cloud arose. I rode my bike the half-mile to the granite landing area as quickly as my legs would peddle. The back side of
Curry Village looked like a ghost town, complete with fog--but that fog was pulverized granite filling the air thickly.
The thought quickly crossed my mind to cover my mouth, but I would not be able to take photos so I pushed it aside. I have some terrific photos, and
a slight gravelly cough.
I was rushing to the source of the dust when emergency personnel caught me. All other civilians had already been evacuated. I wasn't quick enough,
darn!
I was chased out of the excitement zone to join the timid tourists.
The next morning I awoke and contemplated whether to leave my toasty sleeping bag for a jaunt to the restroom. Then I heard a LOUD cracking sound,
much louder than the previous afternoon.
I jumped up and started out of my tent at lightening speed . . . . . only to realize I had better retreat into my tent and put on some clothes!
The crashing seemed like it lasted a long time, but it was probably about 30 seconds. It had ended by the time I ran barefoot but dressed out of my
tent to view Glacier Point above Curry Village. The dust cloud was rising and spreading slowly.
I biked over and tried to reach ground zero, so to speak, but officials had already evacuated everyone to the apple orchard dirt parking lot. I tried
to sneak in a couple different ways on back roads and paths but they were privy to my antics and chased me away. It's not that I tried to be in their
way, it's just that my scientific curiosity is so strong that it overpowers me in such situations.
Rock falls are amazing, incredible displays of raw power. These two bumped and crashed their way down the old ledge trail, along Staircase Falls.
They took out a couple cabins and about five tent cabins. I had been mapping that very area 24 hours prior.
People react differently. I witnessed terror, anger, amazement, and denial. I spoke to folks who ran for their life and then learned their cabin had
been destroyed.
I will always cherish the gift I was given of witnessing such a beautiful geologic event. Yosemite is truly a rock lover's paradise.
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4baja
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Location: morro bay ca
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very stoney geo!
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Paulina
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Do we get to see those terrific photos?
\"Well behaved women rarely make history.\" Laurel Thatcher Ulrich
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Natalie Ann
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Location: Berkeley
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Very exciting stuff, Suzanne. I, too, would love to see the photos.
My girlfriend was also there for the slides - she said the sound and ground shake was both exciting and scary. Likely the two of you were just
missing each other trying to sneak back there in the granite dust for a first hand look.
Nena
Be yourself, everyone else is already taken.
.....Oscar Wilde
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thebajarunner
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Great report...
My daughter and I were hiking up the canyon, past Mirror Lake a couple years ago in the Spring.
We sat down for a snack, looking toward Half Dome.
Suddenly a huge slab of Winter ice broke loose off the walls next to the Dome and we got to witness this massive ice fall, went on for at least 60
seconds.
Not as lethal as rocks, but spectacular, for sure.
Glad you did not get "rocked" in the event.
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Bwana_John
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Registered: 10-17-2007
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Hey Geo....
I've gotta house-jack, wanna head up to the meadows and find a well placed erratic to trundel? 
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Skipjack Joe
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Georock,
Perhaps, as a geologist, you could tell us what caused the rock fall. I would be interested to know.
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Skeet/Loreto
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Thanks Georock. Sure hope you post some Photos.
Makes lots of memories for me and my years watching the "FireFall".
Skeet
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motoged
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| Quote: | Originally posted by Skipjack Joe
Georock,
Perhaps, as a geologist, you could tell us what caused the rock fall. I would be interested to know. |
SJ,
Two key factors: gravity and suction...
Gravity encouraged the rocks to fall ratrher than rise....suction is what kept the fallen stuff on the ground....some say that gravity sucks and
that's what keeps us from flying off the planet as it spins....I personally think that there are the two forces at work rather than just the one
Pictures????
Don't believe everything you think....
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Skipjack Joe
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You're right. If Newton had visited Yosemite we would indebted to a rock instead of an apple.
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Sharksbaja
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Where the hell is Todos Rocas?
DON\'T SQUINT! Give yer eyes a break!
Try holding down [control] key and toggle the [+ and -] keys
Viva Mulege!
Nomads\' Sunsets
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Bwana_John
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Registered: 10-17-2007
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| Quote: |
what caused the rock fall
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Physical and chemical weathering. Rock get crack/joint due to uplift and release of isostatic forces, crack gets water and tree roots, water freezes
and tree roots grow, rock is displaced, undercutting due to glacial quarrying provides relief for fall.
(or Bwana's loose in the Park with a house-jack)
[Edited on 10-16-2008 by Bwana_John]
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BajaGringo
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I saw a photo album a few years back that has documented the change in Yosemite over the past 150 years. It included these events where granite breaks
off and falls. I had printed some of them out and took them with us our last trip there. Was quite interesting and gives you a different perspective
of this Sierra gem...
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Skeet/Loreto
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In addition to the Rock Falls, if you are in Yosemite at the right time, go up to Mirror Lake during a Spring Storm and watch the Lighting Strikes and
Thunder bounce off of Half Dome and the various Points.
Awesome!
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thebajarunner
Ultra Nomad
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Excellent answer on the causes...
They are now saying that it was mostly tree roots,
my previous studies indicated more along the water freezing in the cracks and causing gradual expansion.
Years ago I took a one week San Jose State science class at Yosemite (college never was quite the same after that week)
and our teacher, Carl Sharsmith, "The Sage of Yosemite," told us that in a few thousand years all the sheer walls in Yosemite would have fallen and
the valley would have gradual slopes on the sides, in place of the straight up granite there today.
Interesting thought.
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BajaVida
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admit it runner, slides are caused by global warming
No se apure y dure.
Don\'t hurry and you\'ll last longer.
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thebajarunner
Ultra Nomad
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Left wing "rubbish"
| Quote: | Originally posted by BajaVida
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Keep it up and I will put you in the back of the pickup on our next trip....
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Skeet/Loreto
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"What GOD has put together, let no Man put Asunder"
Yosemite!!!
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