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Minerals
Social climber
The Deli
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Correct, Wes.
Ratajeski, K., Glazner, A.F., and Miller, B.V., 2001, Geology and geochemistry of mafic to felsic plutonic rocks in the Cretaceous intrusive suite of Yosemite Valley, California: Geological Society of America Bulletin, v. 113, p. 1486-1502.
http://bulletin.geoscienceworld.org/cgi/content/abstract/113/11/1486
Hope Valley? Looks like granite! All I know is that I spent a night in the truck there late November and froze my adze off, and then got sick! Ug. What’s with Hope Valley?
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Timid: I agree with Weschrist's interpretation...that's basically what I was going to say.
Weschrist: what hydrogeology project are you working on?
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nature
climber
Tucson, AZ
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where is your field area?
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Weschrist: sounds like an interesting project. So you're looking at spatial heterogeneity in glacial deposits overlying fractured bedrock and how these features influence snow melt recharge of a down gradient wetland? Have you considered using tracers, noble gases, or isotopes like 3H/3He, Rn-222, or Cl36 to evaluate the age distribution of water in the system?
https://ipo.llnl.gov/?q=technologies-groundwater_age_dating
Nimz, G.J., Smith, D.K., Caffee, M.W., Finkel, R.C., Hudson, G.B., Borchers, J.W., and Nimz, K.P., 1992. Isotopic characterization of hydrologic structure and chemical interaction between groundwater and granitic rock in the Wawona basin, Yosemite National Park. Eos, Transaction, Am. Geophys. Union, 73: 170.
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Fritz
Trad climber
Hagerman, ID
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On the YOUR WILDEST TRUNDLE thread /quote] I ask this question?
So------what is the odor from a freshly trundled boulder after impact???
We always thought it was ozone???
Fresh, sharp, and stimulating------and it is not sulphur.
http://www.supertopo.com/climbing/thread.php?topic_id=1135891&tn=0
Anders asks those that frequent this thread to answer my question.
What do you know?
Thanks, Fritz
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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some hydrogeo eye candy...Digital Optical Televiewer images obtained from a 160 ft, 6-inch diameter borehole yesterday in the late Miocene, Neroly Fm in the Altamont Hills, CA. These are oriented 2D images of the borehole wall such that south is the center of the image; north is on either end; east is midway between center and left side; west is midway between center and right side.
This image is from ~139 ft in the vadose zone showing a south-soutwest-dipping (~8 degrees) contact between clayey siltstone and fine-grained sandstone
This image is from ~154 ft showing the water table at about 153.4 ft just above a fractured zone from 154 to 156 ft. We plan to screen this well with 8-inch Schedule 80 PVC casing from 130 to 160 ft as an injection well to discharge treated effluent from a nearby groundwater treatment facility that is removing TCE and perchlorate from the ground water.
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50
climber
Stumptown
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Apr 10, 2010 - 07:49pm PT
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Sweet images Tradster and a welcome distraction from Turbotax today.
The shading contrast between the siltstone and sandstone shows a nice contact. So is the clayey siltstone the darker material in the upper portion of the image? Not sure what to make of the features below the contact. What kind of rig was used to drill the borehole? Any comments on why you have to use an injection well for the treated groundwater as opposed to discharging to surface waters?
OK, back to itemized deductions.
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cintune
climber
the Moon and Antarctica
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Apr 10, 2010 - 08:16pm PT
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More geo-eyecandy; some nice differential erosion at Turnip Rock, Lake Huron:
http://www-personal.umich.edu/~jensenl/visuals/album/2009/portaustin/
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Apr 12, 2010 - 03:35am PT
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Ya was doin' TurboTax this weekend too...finally got through it...all I need now is for the CFO (aka Ingrid) to review & approve it so I can submit it.
WOW cintune that photo of Turnip Rock is wild...I've never seen that before...thanks for posting it. Looks like an image in a Salvador Dali painting.
weschrist...in the 1st Optical Televiewer image I posted above, the clayey siltstone overlies the sandstone. That could be bioturbation in the sandstone.
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Edge
Trad climber
New Durham, NH
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Apr 29, 2010 - 12:52pm PT
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I picked this case up at a yard sale a while back and forgot about it. I just rediscovered it today in my wood shop.
I had this very same kit when I was a kid. This brought back memories of specific gravity tests, burning sulfur to see what it smelled like, and blowing through a little pipe attached to an alcohol lamp. I never did get the hang of continually blowing through the pipe without stopping to inhale; a skill that would have translated nicely to playing a didgeridoo. This kit started a long standing interest in all things geologic.
The case in the photos came only with the original test tubes and rack, and the alcohol lamp and blow pipe.
Don't they look like they are having fun?
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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May 18, 2010 - 09:14pm PT
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Geo-enthusiasts: check out this photo taken last week in the Altamont Hills, CA. There is a 1 to 2 week window in the early spring when the natural grasses are turning from green to brown when this pattern emerges. The grass remains greener longer along joint/fracture patterns due to higher levels of soil moisture.
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HighTraverse
Trad climber
Bay Area
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May 18, 2010 - 11:14pm PT
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I know from nuttin' about geology. Except maybe, sometimes, I can tell Granite from Sandstone. Oh, and usually I can recognize the Franciscan formation.
What's that dark, craggy rock in the middle of the gully?
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kpinwalla2
Social climber
WA
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May 18, 2010 - 11:25pm PT
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looks like a knocker - seriously.... blueschist perhaps?
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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May 18, 2010 - 11:36pm PT
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I'm glad you asked that question. That's a steeply-dipping outcrop of late Miocene-Pliocene Neroly Fm, an andestic-rich, primarily fluvial deposit. Here are some close-up photos.
Planar cross-stratification in Neroly blue sandstone. The blue color is related to a reduced iron-rich authigenic montmorillonoid coating on dark mineral grains.
Well-rounded, primarily andestic conglomerate. The provenance of the andesitic cobbles is the Stanislaus volcanic center in the Sierra Foothills.
Measuring dip using a Brunton compass.
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Gary Carpenter
climber
SF Bay Area
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May 18, 2010 - 11:58pm PT
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Same pattern in grasses can be noted on the Sunol grade
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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May 19, 2010 - 12:12am PT
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Blue sandstones of Central California...
DOI: 10.1306/74D70BF5-2B21-11D7-8648000102C1865D
Genetic Relationship Among Tertiary Blue Sandstones in Central California
J. F. Lerbekmo
Journal of Sedimentary Research
Volume 31 (1961)
ABSTRACT
Pliocene sandstones with a striking bluish hue are prominent along the western base of the Sierra Nevada Range in the Mehrten Formation, and in the Coastal ranges of central California in the Tehama, Neroly, Cierbo, Purisima, San Joaquin, and Etchegoin formations. The color has previously been shown to be due to a thin authigenic montmorillonoid coating on the dark-colored sand grains. These coated sandstones have in common a preponderance of andesitic detritus and a high degree of permeability. Interbedded coated and uncoated sandstones occur as a result of differing degrees of permeability, or, alternate derivation from andesitic and non-andesitic source rocks. Compositional and cross-stratification studies indicate that andesitic sandstones of the Mehrten, Etchegoin, and San Joaquin formations were derived from the Sierra Nevada; those of the Cierbo and Neroly formations, in addition to a major source in the Sierra Nevada, probably had some contribution from the Coast Ranges; the Tehama sediments were derived from the Coast Ranges; and the Purisima blue sandstones may have been derived from either Coast Range of Sierran effusive rocks to the east.
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dipper
climber
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Topic Author's Reply - Aug 9, 2010 - 09:01pm PT
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Minerals and other rock hounds,
I was in the area described in my post #205 of this thread and came across what you see in the following images.
The dark, in the dark and light alternating samples is a fine powder ( though hard to touch) stuff that has precipitated out of the main mass. Both light and dark are hard and course to the touch, like 40-grit sandpaper.
Am told that this area includes a "salt-lick" used by local sheep.
What say ye about these minerals, Minerals?
Thanks in advance.
Image 1
Image 2
Image 3
Image 4
Image 5
Image 6
Image 7
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Dipper: your initial post was from the Pt Reyes area...these photos look like they're from the East side of the Sierras.
Looks like metamorphic rocks and since they're layered their origin is probably sedimentary or volcanic. So meta-sedimentary or meta-volcanic rocks. Looks like some chemical alteration, so there could be contact metamorphism. Based on the rhythmic bedding ~ 1 to 5 inches in thickness?, with alternating dark thin layers & coarser, quartz-rich? layers, it looks like episodic deposition in a distal facies of an alluvial or submarine fan or delta, where quartz-rich sediments or rhyolitic volcaniclastics are being deposited. That's my WAG.
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dipper
climber
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Topic Author's Reply - Aug 9, 2010 - 09:34pm PT
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My Bad TT,
I changed it to say post #205.
Thanks for the WAG, and yes, eastern sierra.
I have two small samples if interest warrants seeing them up close and all.
Am told that the stuff sliding north out at Point Reyes was once down on the southern tip of the Sierra.
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