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View Diary: DKos Special Supplement: Plate Tectonics And The World’s Changing Geography (Part 2 of 2) (68 comments)

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  •  I studied undergraduate geology in the mid-'70s (10+ / 0-)

    in a well-respected Midwestern state university. Most of the professors were middle-aged or older and pretty much all I heard about was geosynclinal theory, something I never quite bought and found difficult to conceptualize.

    I then went to graduate school at the end of the '70s in the west, and there all anyone talked about was plate tectonics.  It was like someone turned on a light in what had been a dark room.  In a way, plate tectonics is almost what could be considered a unifying theory for geology. Not as much so as natural selection is for paleontology and biology, but it responds to so many disparate empirical observations about landforms and (especially continental margin and oceanic ridge) geologic processes that it's truly an impressive theory.

    From one of my retiring professors in graduate school I inherited a complimentary advance copy of the English translation of Debate About the Earth -- Approach to Geophysics through Analysis of Continental Drift by three University of Tokyo professors: Hitoshi Takeuchi, Seiya Uyeda, and Hiroo Kanamori.  It's a very good read, and -- I have to admit -- gave me considerable respect for Japanese scientists; something that seems odd to say now, but for a young person who had never met a Japanese person until college and who grew up as an Air Force brat on various military bases in the aftermath of WWII, it was (I'm embarrassed to say) a revelation.

    As for your diaries over the past two days -- thank you for writing them. It's obvious you put a lot of work into them and I think it's helpful for non-geologists to be exposed to this material. I have, however, a couple of suggestions:

    1.  Consider splitting this up more. The diaries are quite long and challenging to wade through. This diary could easily be three.

    2.  Just below the photo of the collapsed dome of the Christchurch Catholic Cathedral, you state this:

    Continental plates, which are mainly composed of granite, are heavier than oceanic plates, which are most basaltic (lava-based).
    Granted, elsewhere in the diary you've mentioned several times that the mafic oceanic plates are denser than the granitic continental plates, but the use of the term "heavier" here might be confusing.  You may want to explain that, although the oceanic plate is denser, which why it subducts under the continental plate where they converge, the continental plates, overall, are heavier because of their greater thickness.  And when two continental plates converge, as they did when the Indian Plate pushed into the Eurasian Plate, you get tremendous uplift of the granitic continental crust -- in this case the Himalayan Plateau. One last thing - in the sentence I've blockquoted, I think you meant mostly basaltic, not most basaltic.
    •  Never understood geosynclines (3+ / 0-)

      I was in school about 5 years before you, and it was only in our late junior and senior year that plate tectonics was much discussed in an undergraduate setting anyway.  My Geology 101 text was Principles of Physical Geology  (2nd ed) by Arthur Holmes).  

      I was at another Southern CA university and we had a field trip probably in 1969 or 1970 to UCLA to listen to a lecture by John Dewey about plate tectonics.  Immediately, that made so much more sense than geosynclines to explain orogenies and mountain belts!   Our structural geology prof was also a big fan to Tanya Atwater at that time.

      •  TAnya. . . (2+ / 0-)
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        celdd, RiveroftheWest

        the marine biologist and plate tectonic experts. . .I still have a paper somewhere in my stacks of stuff. . .authored by her. I haven't heard of her name for years. She was also an influence on me (then and now). And Art Holmes book. . .that 101 text...I know the name, though not the book. I think I"ll look it up and see what's new in his geology stuff. I guess there was no much misunderstanding about geosynclines that the theory was harsh to follow in greater detail (and later replaced by plate tectonics). I think there were also subdivisions of geo s's, such a miogeosyn. and eugeosyn. contingent on mountain system rock strata or some such. All in all, I find plate tectonics easier to follow, but going back to the inception of geosynclines, as theory, that must have been a revolutionary concept at the time to ponder. Anywy, thanks for posting your comments celdd. Looks like another geologist just signed in and adds to the richness of this overview subject I didn't even think would find interest with our community. How nice to be wrong sometimes!

        Treat the world (yourself, and others) as part of a living organism. Everyone and everything will benefit.

        by richholtzin on Wed Apr 17, 2013 at 06:31:47 AM PDT

        [ Parent ]

    •  I am deeply grateful. . . (2+ / 0-)
      Recommended by:
      Jim R, RiveroftheWest

      for your suggestions, Ernest T Bass, and concur with your address on this matter (your reply). And, si, "heavier" is a bit misleading. And, yes, the trouble with me and not working with an editor is the sometimes typing errors. . .mostly basaltic, it is. If you don't mind, I would like to contact you at your profile email address and discuss at length some more of what you ran by me. Fascinating stuff, really, and I'm not sure many community folks will enjoy reading all my verbiage on the matter. But I would like to get some things discussed between us and right now I am moving this week, my Internet will be spotty at best, so maybe over the weekend might do. Until then, thank you so much for posting such an informative and helpful reply. I only know so much given any subject and when knowledgeable others, like you, feed my mind even more, well, I'm learning like I always do. . .and thanks for 'learnin' me as bad grammar goes.

      Treat the world (yourself, and others) as part of a living organism. Everyone and everything will benefit.

      by richholtzin on Tue Apr 16, 2013 at 12:22:28 PM PDT

      [ Parent ]

      •  The upper crusts are granitic & basaltic (1+ / 0-)
        Recommended by:
        RiveroftheWest

        The lower halves of the plates consist of denser material. The continental plates have basaltic bottom halves and the oceanic plates have ultramafic bottoms.

        Yes, it's a matter of relative densities, not weights. That's one simplification too far.

        The mechanics of geosynclines never made sense to me either.

        look for my eSci diary series Thursday evening.

        by FishOutofWater on Wed Apr 17, 2013 at 07:49:40 AM PDT

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        •  hell, we both can't be 'rong (sic), right? (2+ / 0-)
          Recommended by:
          RiveroftheWest, FishOutofWater

          just kidding. When it comes to specifics about specific topics I tend to play it say and shrug my shoulders. Your erudition on ultramafic bottoms and such. . .spot on. As for geosynclines and its theories. . .as I stated I'm a plate man and thinker. Just makes more sense to me. Surprising, too, how far geology, the youngest of all earth sciences, has come in, say, 50 years. What will tomorrow bring, indeed?

          Treat the world (yourself, and others) as part of a living organism. Everyone and everything will benefit.

          by richholtzin on Wed Apr 17, 2013 at 08:26:22 AM PDT

          [ Parent ]

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