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dipper
climber
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Topic Author's Reply - Jan 21, 2010 - 03:32pm PT
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Minerals,
I figured that was epidote. But it was too nice to not post.
Here is a tighter shot of that ridge top you like. It is pretty big, but I figured the detail was worth it.
It is on the ridge east of Mt. Baxter. That whole area is amazing even to me.
I imagine you pro rock-heads would go nutz.
When it stops raining, I will dig out some of my smaller ballast and take some pics.
I have two small cannon-ball like objects from this area. They are layered like an onion, about the size of a baseball.
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Klimmer
Mountain climber
San Diego
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Jan 21, 2010 - 03:44pm PT
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It is cleaving along the banding pattern, that indicates it is Metamorphic to me now. But what kind of metamorphic rock? I'll come back later.
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Minerals
Social climber
The Deli
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Jan 21, 2010 - 06:58pm PT
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Hey, Studly, I think you know more about rocks than you think you know. How many non-geologist, non-climbers can look at a rock or even a photo of a rock and say… Nah, that doesn’t look like such and such, it looks more like this and that… We climbers get to see a lot of rock, but as obvious as that may sound, there are a lot of geologists out there who wish they could see all the things that we see. And after climbing for a little bit, you get to know the rock, whether it is here or there, this or that, how it feels and what it looks like up close and… hey, what are those things that you are hanging on to…?
Hey, how about the book Flakes, Jugs & Splitters: A Rock Climber’s Guide to Geology?
I think Sarah summed it up nicely in her second to last post (7/5/09) in this thread:
http://www.supertopo.com/climbers-forum/884866/the_geology_of_rock_climbing
Some neat geology in the thread, as well! Where are you guys?
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Minerals
Social climber
The Deli
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Jan 21, 2010 - 06:59pm PT
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Klimmer, good point about the rock cleaving along the banding – that does seem more apparent in Dipper’s second photo. I still think it looks like an intrusive rock. The dominant set of joints in both photos is oriented perpendicular to the banding. If the banding represents foliation/layering in a metamorphic rock, I would usually expect the dominant joint set to be parallel to the foliation/banding, which it isn’t. The freshly fractured patches of rock in the first (larger) photo don’t seem to follow the banding pattern. The loose chunks don’t have the shape that one would expect of a foliated metamorphic rock and they just have that “granitic look” to me – shapes, angles, texture… The planar surface that shows banding is probably another joint surface that has been exposed to more fluid flow/weathering than the rest of the rock.
Yeah, Dipper, looks like epidote. Tough to tell what the other stuff is from the photo. The Mt. Baxter area looks cool – there is so much neat stuff in the High Sierra, more than a lifetime of exploring to be had… I will keep that area in mind.
“I have two small cannon-ball like objects from this area. They are layered like an onion, about the size of a baseball.”
Hmmmmm… Granitic? Layered as in weathering or layered as in mineral composition? Have you found a couple of orbicules? Or maybe not…?
Minerals sayz... WOW!
Image from Wikipedia, found here:
http://en.wikipedia.org/wiki/Orbicular_granite
I hear that there is some orbicular granite to the west of Donner Pass but haven’t been out to find it yet – a professor (Hibbard) told me about it and put a dot on a topo map. Now I just need to find that map… :)
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corniss chopper
Mountain climber
san jose, ca
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Jan 21, 2010 - 07:04pm PT
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Horse Creek , Northern edge of Yosemite NP.
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Minerals
Social climber
The Deli
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Jan 21, 2010 - 07:24pm PT
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Looks like there’s a story behind that one, Corniss Chopper.
Hmmmm… Hey Dipper, are those angular chunks of granite in your second grey rock photo? I am having a hard time seeing the details on this laptop screen. If so, and they are not deformed, then that pretty much sums it up.
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50
climber
Stumptown
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Jan 21, 2010 - 08:44pm PT
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Came across this story today that a few of you petroleum geologist might enjoy...
http://www.vacationideas.me/asia/the-door-to-hell-burning-gas-crater-darvaza-turkmenistan/
Darvaza Burning Gas Crater
Turkmenistan is very rich in natural resources. Currently a sovereign country, Turkmenistan was part of the Soviet Union until 1991. It was during rule of Soviet Russia, back in 1971 when geologists were conducting gas drilling in Kara-Kum desert and discovered an underground chamber close to the village of Darvaza (known in Turkmen as Derweze, but sometimes also referred to as Darvaz). The discovery of the chamber was accidental and resulted in drilling rig collapsing, leaving giant gas crater filled with poisonous gases exposed to the world outside. The concentration of gases within the crater was high so nobody dared to go down there. It was then when someone came with an idea to light the gas in the crater on fire so as to burn it before the poisonous fumes engulf the nearby town of Darvaza.
The geologists thought the idea of burning the gas was smart and went ahead with lighting the crater on fire. As it turns out, the supply of quality natural gas below the crater is near infinite as the crater’s been burning since. At the time of this post, on June of 2009 the gas crater in Darvaza is still burning and has been since 1971 without interruption. No one can even imagine how much quality natural gas was burnt throughout the 38 years of the crater being on fire. No one can estimate how much more gas there still is. When they first lit the gas crater on fire, they thought the fire would go out after a few days. It’s been more than a few day, it’s been more than a few weeks or months. It’s been decades and the gas crater is burning just as it did the day it was first lit. Putting all economical loses from wasted natural gas aside, imagine the ecological impact this burning gas has cause during decades of non stop burning!
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Jan 21, 2010 - 09:18pm PT
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cool photos everyone
corniss chopper: is that horse creek peak?
50: interesting story...thanks for posting that.
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Minerals
Social climber
The Deli
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Jan 21, 2010 - 09:55pm PT
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Yeah, really cool article, 50! Thanks. Do they do primitive sacrifices there when the tourists are away? >:)>
Quoting myself from above:
“The dominant set of joints in both photos is oriented perpendicular to the banding. If the banding represents foliation/layering in a metamorphic rock, I would usually expect the dominant joint set to be parallel to the foliation/banding, which it isn’t.”
I need to correct myself on this. The “dominant” joint set or cleavage in a metamorphic rock does not always have to be parallel to the foliation – it can be common to see a well-foliated rock that is jointed at high angles to the foliation. I guess what I was trying to say is that as far as an obvious cleavage in the rock, the main section of outcrop in the first photo looks pretty solid (aside from the main joints). As a whole, the rock just doesn’t have that planar metamorphic weakness look to it (foliation, etc.) and the lighter-colored banding looks like alteration. In some places, the rock is cleaving along the bands; the alteration bands probably formed along tiny parallel fractures, which are a slight weakness in the rock. The darker color on the planar surface could also be mineralization (tourmaline, amphibole, pyroxene, etc.) that formed along the joint at the same time as the alteration (white bands). There may even be tiny bits of epidote in there too!
OK, how’s about this? Where is it? (Where else could it be...?) How many different rock types? Names of rock types? What’s older and what’s younger? And while we’re at it, name the two routes!
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Jan 22, 2010 - 02:37am PT
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I'm no aficionado but that's el cap between the NA Wall & East Buttress
here are my WAGs RE the routes...
Lost in America & Born Under A Bad Sign
from oldest to youngest...
El Cap Granite
Granodiorite
Diorite & Gabbro? dikes cutting El Cap Granite
looks like there might be some younger cross-cutting quartz-feldspar rich dikes but can't tell from this photo, could be weathering features.
Some of the contacts between intrusive rock types are quite linear and look more like fault? joint? contacts than intrusive contacts.
What does this sequence indicate about the chemical evolution of the magma chamber(s)?
Is there any Taft Granite visible in this photo or is that granite located higher up on el cap?
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Jan 22, 2010 - 02:56am PT
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This is a GoogleEarth image from northern foothills of the Avawatz Mts just south of Death Valley that was mentioned in one of the early posts to this thread. The NW-trending light colored rock in the center of the photo is pre-Cambrian granite-gneiss in the core of an anticline that is flanked by Pleistocene-Quaternary Playa Lake, Evaporite, and Alluvial Fan deposits. This structure is located at the southern terminus of the Death Valley fault zone where it merges with the eastern terminus of the Garlock Fault zone.
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Minerals
Social climber
The Deli
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Jan 23, 2010 - 01:33pm PT
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Tradster, I missed your new posts the other day. Yeah, Lost in America on the left; the other route is an “easy” route…
Good work on the El Cap rock types. Guess I need to do some El Cap typing at some point here. Would help if I had the Ratajeski/Glazner paper in front of me…
Cool image! Your field area? GoogleEarth RULES!!!
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Minerals
Social climber
The Deli
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Jan 23, 2010 - 01:34pm PT
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Well, after Fritz’s difficult mineral quizzes, how about some easier ones…
What is the “blue iridescent” mineral that makes up most of this rock?
Polished surface of countertop slab material scrap
The white mineral is calcite (notice the rhombohedral cleavage). What is the other mineral?
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Minerals
Social climber
The Deli
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Jan 23, 2010 - 01:58pm PT
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Thanks, BASE104. Here’s an image of Yosemite Valley – the joint sets are rather obvious and in some area, control the shape and orientation of the Valley. GoogeEarth might be better…
Yeah, strain (deformation in a rock) results from stress (force).
Image found here: http://rst.gsfc.nasa.gov/Sect6/Sect6_9.html
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gstock
climber
Yosemite Valley
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Jan 23, 2010 - 02:00pm PT
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I've always considered the rock face near the fifth pitch of Tangerine Trip to be the most beautiful on El Cap, and seeing it up close confirmed that for me. The combination of near-horizontal aplite dikes and vertical orange and gray water stains is really spectacular. Fun lower-out from there also!
Greg
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Jan 23, 2010 - 06:18pm PT
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Minerals: The blue iridescent mineral above is labradorite.
My WAG for the mineral associated with the calcite...chlorite?
Cool photo of Yosemite Valley...really shows how regional joint patterns control valley/canyon orientation. In the case of Yosemite Valley these joints are essentially orthogonal...NNE-SSW and the other WNW/ESE
Here's a photo I took a couple of weeks ago on a flight from Oakland to Phoenix. I believe the area is Sequoia/Kings Canyon but not sure. In any case, the snow-filled gullies show what appears to be a conjugate joint pattern in the granite.
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Minerals
Social climber
The Deli
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This thread is not dead!!!
Yeah, Tradster, looks like at least a couple of joint sets on that snow-covered ridgeline. Cool! Yes, you are correct on the blue mineral – labradorite, a variety of plagioclase feldspar that is commonly used for countertops because of its neat iridescent color. The second mineral with the calcite is not chlorite, but it is soft. Close guess.
Labradorite:
http://en.wikipedia.org/wiki/Labradorite
Man, I’ve got more catching up to do in this thread…
But for starters, how ‘bout that photo that Dipper posted a little while back, from the ridgeline east of Mt. Baxter?
Dipper’s post up-thread with original photo found here:
http://www.supertopo.com/climbing/thread.php?topic_id=1048215&msg=1064721#msg1064721
With the help of Tuolumne_Tradster, I have learned how to overlay geologic maps onto Google Earth. WooHoo! Thanks, man!!! So, with the view in Dipper’s photo as a reference, I tried to figure out where the photo was taken from, using Google Earth. I wasn’t able to attain the exact perspective because I couldn’t go low enough without bumping into the ground, at which point the eye elevation and angle of view jump and then things get all out of whack (seems like a bug in the software to me…). Anyways, this was about the best I could get – the foreground has no texture because, out of all of the satellite coverage in the Sierra, THIS area had to have some cloud cover. Oh, well… You get the idea.
Dipper’s original photo from the ridgeline east of Mt. Baxter
(Hope you don’t mind that I borrowed it!)
Google Earth view in 3-D, looking NNE, from the approximate location where the above photo was taken. Notice similar features (topography and color) between photo and 3-D image; foreground is obscured by “cloud cover” and lacks ground view
Same view as above but with a map overlay - USGS Mount Pinchot Geologic Quadrangle
View showing Mt. Baxter and the ridgeline to the east where I have approximated the location of Dipper’s photo. The transparency of the geologic map overlay can be adjusted in Google Earth such that the base image can also be seen, as you can see in this image
Another view, slightly different than the previous, but with the geologic map overlay set at 100% (0 transparency… political remarks withheld…;)
Google Earth map view of the Mt. Baxter area. Based on my approximation of the location of Dipper’s photo, the rock in the photo is mapped as “Km”
Cropped section of the USGS Mount Pinchot Geologic Quadrangle map, showing the Mt. Baxter area. Note unit “Km” as seen in previous image. Also note that the summit of Mt. Baxter is composed of unit “Kta”
For more detail and info, and an explanation of geologic map units, the full map can be found here:
USGS Mount Pinchot Geologic Quad Map (5.84 MB):
http://geomaps.geosci.unc.edu/quads/fulls/Mount%20Pinchot.jpg
From the explanation of rock units:
“Km – Mafic plutonic rock
Mafic granodiorite, quartz diorite, diorite, gabbro, and peridotite. Commonly intimately mixed with granitic material and metamorphic rocks and cut by granitic dikes. Includes dikes of remobilized mafic plutonic rock.”
This unit (Km) is mapped as the oldest plutonic (intrusive igneous) unit in the map area. With that considered, it is even more likely that the rock has been altered (striations in Dipper’s photo), given its older age and the subsequent igneous activity in the surrounding area. The lighter blobs/chunks of rock in the lower right of Dipper’s photo may be part of the “granitic material” and/or “granitic dikes” mentioned in the unit description above.
“Kta – Tinemaha granodiorite
Woods Lake mass. Slightly porphyritic granodiorite and quartz monzonite”
The many red lines on the map are mafic dikes (dark in color) of the 148 million-year-old Independence Dike Swarm. Note that units older than 148 Ma are cut by the dikes, yet units younger than 148 Ma truncate the dikes – simple cross-cutting age relations.
Some info on the Independence Dike Swarm:
http://geology.geoscienceworld.org:80/cgi/content/abstract/7/3/129
http://gsabulletin.gsapubs.org/content/112/3/504.abstract
http://www.geolab.unc.edu:80/Petunia/IDS_Web_Site/FTG.html
(lots of info)
Additional geologic quad maps of the Sierra Nevada can be found here:
http://geomaps.geosci.unc.edu/quads/quads.htm
Geologic maps of Yosemite Valley as well as the entire Park can be found here:
http://geomaps.geosci.unc.edu/parks/parks.htm
Enjoy!
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Minerals
Social climber
The Deli
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Wes, Tradster is correct, although we are leaving out Taft granite. The North America diorite cuts older El Cap granite and hybrid tonalite dikes. The aplite/pegmatite dikes and pods are the youngest intrusions on the face.
I don’t know anything about Squamish, but I would guess that the granitic rock is Cretaceous in age. Nice photo. That dike looks quite linear, with sharp contacts with the host granitoid. My guess would be that the dike is a Tertiary basaltic dike that fed surface volcanism above. It is quite common to see Tertiary mafic dikes cutting Mesozoic granitoids in the Nevada desert.
The relations between the various rock units on El Cap are quite interesting and somewhat complex – the SE face is an amazing window into the workings of plutonic systems. I should write more on that…
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Awesome Minerals...looks like you've put the GoogleEarth geologic map overlays to good use.
Timid TopRope...interesting problem...will have to think about this one.
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Minerals
Social climber
The Deli
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Yeah, Tradster, Google Earth is freakin’ AWESOME! What an amazing tool. Thanks again for all of your help with that! I’m psyched.
OK, I will try to start thinking about El Cap again. But I feel a little hesitant to write too much without Ratajeski’s paper in front of me, which is filed in storage. (Note to self… get bolt kit and geo files from storage…)
The wannabe igneous petrologist in me thinks that Timid’s third photo kinda looks like the surface of a volcanic flow. Are those petroglyphs petrified?
“btw, anyone want to assess the stability of One Of These Days wall in Woodfords? I'm sure it will probably stay there until we get a big shake, but it always kinds sketches me out.”
Sounds like a job for Greg and Cleo! Although I might be able to relate to the climbing part…
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