the beauty of stone - post your pics

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Messages 101 - 120 of total 140 in this topic << First  |  < Previous  |  Show All  |  Next >  |  Last >>
tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Feb 18, 2019 - 05:27pm PT
Volcaniclastic breccia &...

...blueschist of the Franciscan Complex near Jenner, CA


tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Feb 20, 2019 - 09:36am PT
Mani stones...

mouse from merced

Trad climber
The finger of fate, my friends, is fickle.
Feb 20, 2019 - 08:48pm PT
tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Feb 20, 2019 - 11:18pm PT
Meta-volcaniclastic? rock near Tengboche Monastery, Khumbu region, Nepal...

mouse from merced

Trad climber
The finger of fate, my friends, is fickle.
Feb 24, 2019 - 08:30am PT
mouse from merced

Trad climber
The finger of fate, my friends, is fickle.
Feb 24, 2019 - 02:07pm PT
mouse from merced

Trad climber
The finger of fate, my friends, is fickle.
Mar 6, 2019 - 07:50pm PT

tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Mar 6, 2019 - 08:41pm PT
Meta-sedimentary rocks of the Jurassic Mariposa Fm collected on Hwy 140 west of Mariposa.

Happiegrrrl2

Trad climber
Mar 6, 2019 - 09:57pm PT


I have one more session left to work on cutting stones before I leave Quartzsite. Finally feel like I have a basic understanding, but only that. People say it's easy to do, and maybe it is. But it's not so easy to do it well.
mike m

Trad climber
black hills
Mar 6, 2019 - 10:06pm PT
tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Mar 7, 2019 - 09:31am PT
High grade metamorphic olistolith in Franciscan meta-sandstone melange, Point Bonita, Marin County, CA

mouse from merced

Trad climber
The finger of fate, my friends, is fickle.
Mar 7, 2019 - 09:35am PT
I bet you can't say that real fast three times. :0)
tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Mar 7, 2019 - 05:31pm PT
Quaternary caldera-forming rhyolitic ignimbrite (aka Bishop Tuff) from the ORG ;-)...


This is an excellent paper on the geology of the Long Valley Caldera & the ORG...
https://pubs.usgs.gov/sir/2016/5120/sir20165120.pdf
Minerals

Social climber
The Deli
Mar 7, 2019 - 08:30pm PT

^^^ I see sanidine. And fiamme.

Itís cool to see small pieces of granitic or metamorphic rock in the Bishop Tuff.

Good stuff, Tradster. Thanks for the link. When I first opened the article and saw the title, I wondered if Wes was one of the authors. Sure enough.
tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Mar 7, 2019 - 10:31pm PT
You can really see the Sanidine in these photos [rectangular, colorless, glassy crystals]. Some amorphous glassy blobs of quartz, too. Fiamme in the form of collapsed lithic and pumice fragments.



I just found this recent paper on precise 40Ar/39Ar age dating of single Sanidine crystals in the Bishop Tuff (BT) by incremental heating, multi-collector mass spectrometry (IH MCMS) at 764.8 ka, shortly after the Matuyama to Brunhes magnetic polarity reversal.
https://pdfs.semanticscholar.org/0347/459ec0dcc1aea7bc24254ffda9b3fef712b1.pdf

In this paper on Compositional Zoning of the Bishop Tuff,
https://academic.oup.com/petrology/article/48/5/951/1472295
they talk about the eruption taking place over a 6-day period. I'm curious what dating method that is based on that has diurnal temporal resolution. Imagine watching the eruption of the BT from the summit of Mt Dana...Mammoth Mt would probably have been too close for comfort.

EDIT: In this 1997 J. of Geology paper
https://www.journals.uchicago.edu/doi/10.1086/515937
Wilson & Hildreth describe using fall deposit chronometry (volcanic ash accumulation rates based on modern observed volcanic ash deposits), to estimate ~ 6 days for the BT deposition.

The new stratigraphic framework shows that much of the Bishop ignimbrite is intraplinian in nature, and that fall deposits and ignimbrite units previously inferred to be sequential are largely or wholly coeval.
Gnome Ofthe Diabase

climber
Out Of Bed
Mar 8, 2019 - 08:15am PT
BEAUTYIS IN THE EYE OF THE BEHOLDER
mouse from merced

Trad climber
The finger of fate, my friends, is fickle.
Mar 9, 2019 - 07:49am PT
Beautiful no matter how it's spelt.
Fritz

Social climber
Choss Creek, ID
Mar 9, 2019 - 08:26am PT
spessertine garnet on quartz.


Barite


fluorite


aquamarine & muscovite mica

Minerals

Social climber
The Deli
Mar 9, 2019 - 09:29am PT

Nice texture photos, Tradster. Iím guessing that the summit of Mt. Dana might have been a bit hostile during that week Ė spectacular views at the beginning of day 1, although probably quite temporary views. Thanks for the three more links. I read the abstracts and saved the two PDFs. Sure is nice to be able to store papers in PDF format on a computer, rather than in file boxes full of real paper. Reminds me of a story...

When I was in school at UNR, I was downstairs in the science library one day, photocopying papers from geology journals, and had a mishap. They often bind several journal issues into one binder/book, which makes it difficult to fully open the pages, to get a photocopy of an entire page. So, as we all have done, I was pushing down on the binder to flatten the pages as I was copying, and unfortunately didnít realize how thin the glass on the photocopy machine was. : ) Well, next thing I know... SMASH!... there goes the glass. Oooops, sh#t, I thought. There was a girl/lady sitting over at a near table, who immediately looked up when she heard the semi-loud noise, with a look of WTF? on her face, but she didnít say a word. I went upstairs to the front desk, and told the old guy there what had happened, who then had a look of disbelief on his face, but acknowledged that it can be difficult to copy pages when they bind so many issues together. I felt bad about it at the time, but get a good laugh out of it now. : ) LOL...


Mouse, do you see the sharp contact in your second El Cap photo, which can also be seen in your first photo? The right-facing corner in your first photo is the ďrivet cornerĒ on Tribal Rite Ė pitch 3. The topo in the SuperTopo book has this feature drawn more accurately than the topo in the Sloan book. The feature in your second photo obviously needs no explanation.


Fritz, your quartz has parasites! Nice stuff.
healyje

Trad climber
Portland, Oregon
Mar 9, 2019 - 10:55am PT



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