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Klimmer
Mountain climber
San Diego
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Hey Geo-gurus,
Just got back from Bishop for Spring Break with the family. Enjoying the thread. Read it from end to end. Good stuff.
HS science teacher here teaching Physics and now, finally, San Diego Unified School District has brought Earth Science back, so a collegue and I are teaching Earth Science at our HS as well. Having to dust off a lot of my college texts. This is good stuff. I really enjoy these discussions. You all are leading me to great resources and "I be learning" a great deal from the discussion. Thanks.
I'll have to come up with some good questions, and try to contribute to the mineral discussions as well.
My personal collecting weaknesses are Fluorescent Minerals (great cross-over with Physics and Mineralogy - and the color is just intense, a major "wow" effect on people) and Meteorites. There is something very special about holding a rare meteorite in hand with bizarre mineralogy (and sometimes with unique minerals and assemblages not found anywhere on Earth) and having a formation age dating to the beginning of our Solar System 4.6 + Billion years, and sometimes even older (Nebular).
Love this stuff.
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Donny... the OHHH!- Riginal
Sport climber
Straight outta Compton!
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Strange coincidence too....this from two years ago...
"I'm sorry Donny, you'll have to enroll in "Busting Donny's moms' chop's 101" to get the graph to differentiate crack-cocaine and crystal meth." from Nature
Then this from yesterday's "Rockhounds of the world unite" thread.
"(btw, can't see any pics except Donny's mom's stash... otherwise I would comment cus I love rocks)." from Weschrist
You people need to leave my crack-head mother out of these bashings...I'm dead serious.
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nature
climber
Flagstaff, AZ
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Topic Author's Reply - Apr 7, 2007 - 01:56pm PT
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yeah wes, those circles make the discussion of topics like rap bolting vs ground-up Lite&trade.
in regards to changing from a subduction zone to a transitional strick-slip boundary. If I'm reading that right, which I think I am, from everything I remember that is the accepted theory: The spreading center was subducted - well, the plate east of the center, and the boundary became what we now call the San Andreas (not sure what the historic subduction zone boundary was called). The theory explains a whole bunch of things - like why we have extension (local and regional) along a compressional boundary.
I tried to follow your isotope clock discussion but I never really wrapped my brain around that stuff back in the day so i'll have to re-read it just to understand it (and not comment as I really won't know what I'm talking about there).
surface process and landscape evolution == the darkside?!?!?!? WHAT?!?!?! Say it ain't so! even darker, then, I suppose would be soils geomorphology. Darth is my dad.
I think you should buy us a beer anyway. And then we can buy you a beer and so on and so on. All the while discussing isotopes, slab windows, plate rafting, or any geomorphic topic that comes to mind. We'll just need help picking up the bottles in the morning.
Donny: I'm sorry about the comments regarding your mom. Rehab is an option though...
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Phil_B
Social climber
Hercules, CA
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Did I hear something about subduction under North America? My tectonics professor at UCSB, Tanya Atwater, wrote the paper that is always referenced when talking about that:
Implications of plate tectonics for the Cenozoic tectonic evolution of western North America. Bull. Geol. Soc. Amer., v. 81, p. 3513-3536.
The cool thing is that she's also put out some animated gifs and Quicktime movies that show it very well.
http://www.seismo.unr.edu/ftp/pub/louie/class/333/atwater/
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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DMT: just read your post ^^^ more carefully about discovering granitic rocks where you wouldn't expect them. Astute observation on your part. When I saw this earlier today, I knew Stony Creek Formation rang a bell. Turns out a friend of mine at UC Davis, Paul Bertucci, back in the late 1970s, did an MS Thesis on...Petrology and Provenance of the Stony Creek Formation, Northern Sacramento Valley, CA
http://archives.datapages.com/data/pac_sepm/048/048001/pdfs/1.htm
Those granitic rocks you found in that conglomerate may have been derived from as far north as the Klamath Mountains and originally deposited as the initial pulse of Great Valley Sequence deposition in a submarine environment by a turbidity current. Although there's not a lot of granitic material described in the Stony Creek Fm according to these papers.
Some more info here...
http://www.ucmp.berkeley.edu/science/profiles/erwin_0609geology.php
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Cragar
climber
MSLA - MT
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Thanks nature!! Love this stuff! Another fun thread to catch up on..
Do you work for the USGS in Flag? When I lived there I did a couple rides in Sedona with 2 guys from the USGS, younger guy on an SS-Surly and I can't remember the other but they are friends of Gullo...
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Surpless, K.D., Graham, S.A., Covault, J.A., & Wooden, J.L. (2006). Does the Great Valley Group Contain Jurassic Strata? Reevaluation of the Age and Early Evolution of a Classic Forearc Basin. Geology, 34(1), 21-24. doi: 10.1130/G21940.1
The Great Valley Group has been linked to the Klamath Mountains from its earliest depositional history by south-directed paleocurrent indicators (Ingersoll, 1983), Klamath-derived chert-rich conglomerate (Bertucci, 1983), and distinctive sandstone compositions (Ingersoll, 1983; Short and Ingersoll, 1990)
Also, this Ingersoll paper...
Ingersoll, R.V., 1983, Petrofacies and provenance of late Mesozoic forearc basin, northern and central
California: American Association of Petroleum Geologists Bulletin, v. 67, p. 1125–1142.
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