Re: [asa] Plate tectonics

What was the prevailing idea prior to plate tectonics and how was that overturned?

(I enjoyed your overview, Charles.) Prior to plate tectonics there wasn't a competing model, because continents generally were not thought to undergo lateral motion. Vertical motions of rocks were treated under the principle of isostasy--which is still useful as modified by plate tectonics considerations. One example is that rocks in a basin sink to greater and greater depths as sediments pile up on top. That's why, for example, there are well-defined reef complexes almost two miles below sea level in the Western Canadian basin. The reefs, of course, at one time (in the Devonian) were at sea level or just below it. Most of the world's hydrocarbon reserves originated in processes related to such vertical rock motion.

Don

  ----- Original Message -----
  From: Charles Carrigan<mailto:CCarriga@olivet.edu>
  To: randyisaac@adelphia.net<mailto:randyisaac@adelphia.net> ; asa@calvin.edu<mailto:asa@calvin.edu>
  Sent: Thursday, October 19, 2006 9:18 PM
  Subject: Re: [asa] Plate tectonics

  Hi Randy,

  The idea of faunal succession is simply that the kinds of organisms that have lived on planet Earth have varied through time. That is to say that the kinds of organisms that lived during the Cambrian Period are not the same as those that lived in the Silurian, the Permian, the Cretaceous, the Tertiary, or the Holocene, etc. etc. Numerous species (and higher orders of organisms) and ecosystems have come and gone throughout the history of Earth. This idea was well established before the science of geochronology was able to place absolute ages on certain geologic events.

  The Theory of Plate Tectonics is in many ways a modernization of the Continental Drift hypothesis that was propsed by Alfred Wegener in 1915. The historical development of this idea over the past century is a fascinating one. Wegener's ideas were widely rejected among N. American and European geologists up until the mid-late 1960s. Critics primarily argued that there was no driving force or mechanism that could cause the proposed phenomenon, but other more facetious arguments were made as well. After the idea became completely "out of style" by the late 1920s (and Wegener died in an accident in 1930), the attacks on continental drift turned into insult.
  Some quotes from leading US geologists:

        "[Wegener's method] is not scientific, but takes the familiar course of an initial idea, a selective search through the literature for corroborative evidence, ignoring most of the facts that are opposed to the idea, and ending in a state of auto-intoxication" E.W. Berry (1928)

        "Can we call geology a science when there exists such difference of opinion on fundamental matters as to make it possible for such a theory as this to run wild?" R.T. Chamberlain (1928)

        "the theory of continental drift is a fairy tale." B. Willis (1944)

       Nonetheless, the data supporting his idea continued to grow in the next decades. During the 1950s, it became clear that the apparent polar wander paths (the position of the magnetic pole through geologic time assuming a fixed continent) for different continents did not match up - it had to be the continents, not the poles, that were moving. But the idea still did not gain acceptance at this time. It was rather the new data generated from studies of the ocean floor during the 1950s that ultimately caused the plate tectonic revolution.
        In 1961-1962, Harry Hess and Robert Dietz wrote papers independently describing the ocean ridges as large rift zones, and the term sea floor spreading was coined. Harry Hess entitled his paper "geopoetry", which tells a lot about the atmosphere in which he published. Several other studies supported the idea of seafloor spreading through the 1960s, but it was J. Tuzo Wilson, in 1965, who drew the first map of tectonic plate boundaries.
  The opening of the paper has been described as "the 4 most pregnant sentences in all of geology"

  "Many geologists have maintained that movements of the Earth's crust are concentrated in mobile belts, which may take the form of mountains, midocean ridges, or major faults with large horizontal movements. These features and the seismic activity along them often appear to end abruptly, which is puzzling. The problem has been difficult to investigate because most terminations lie in ocean basins.

  This article suggests that these features are not isolated, that few come to dead ends, but that they are connected into a continuous network of mobile belts about the Earth which divide the surface into several large rigid plates."

  Several other very important studies throughout the late 60s and early 70s solidified the idea as the reigning theory of how the Earth works, but Wilson was the first to use the term "rigid plates" and draw a picture of them.

  In my attempt to summarize the truth claims of geology into a few simple sound bytes, I forgot one major one - the rock cycle. So bump it up to 4 great truth claims. Pretty much all else in geology is details.

  Best,
  Charles

  _______________________________
  Charles W. Carrigan, Ph.D.
  Assistant Professor of Geology
  Olivet Nazarene Univ., Dept. of Physical Sciences
  One University Ave.
  Bourbonnais, IL 60914
  PH: (815) 939-5346
  FX: (815) 939-5071
  ccarriga@olivet.edu<mailto:ccarriga@olivet.edu>
  http://geology.olivet.edu/<http://geology.olivet.edu/>

  "To a naturalist nothing is indifferent;
  the humble moss that creeps upon the stone
  is equally interesting as the lofty pine which so beautifully adorns the valley or the mountain:
  but to a naturalist who is reading in the face of the rocks the annals of a former world,
  the mossy covering which obstructs his view,
  and renders indistinguishable the different species of stone,
  is no less than a serious subject of regret."
            - James Hutton
  _______________________________

>>> "Randy Isaac" <randyisaac@adelphia.net> 10/19/2006 9:23 PM >>>

  Charles,

      When you cite faunal succession as a "great overarching truth statement", are you referring to the contribution of geology to the dating of the various types of fauna that have ever lived? Or is there something else?

      Also, I'm curious about the history of the plate tectonic theory. Wasn't that about 3 or 4 decades ago? What was the prevailing idea prior to plate tectonics and how was that overturned? Was there one particular advocate who is credited with the insight and championing of the new idea?

      Randy
    ----- Original Message -----
    From: Charles Carrigan<mailto:CCarriga@olivet.edu>
    To: asa@calvin.edu<mailto:asa@calvin.edu> ; gregoryarago@yahoo.ca<mailto:gregoryarago@yahoo.ca>
    Sent: Thursday, October 19, 2006 9:02 PM
    Subject: Re: [asa] YEC and ID arguments

    Gregory -

    There are three great overarching truth statements that the science of geology has contributed to the human understanding of life. These are regarding 1) the age of the Earth; 2) plate tectonics; and 3) faunal succession. The plain simple truth is that none of the YEC publications on any of these 3 topics have any credibility whatsoever. Yes, I did say none. I have read many of their works, and after a while it becomes easy to recognize the same old song & dance - a lot of non-sequiter, a healthy dose of ignorance, and a great deal of ignoring the facts. There are no publications by YECs that deal with these issues accurately. Absolutist language might get under your skin, but it Michael's statement is a fact nonetheless.

    If they don't understand the fundamentals of Earth science, then there is little reason to believe they have the answers when it comes to questions about origins.

    Best Regards,
    Charles

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Received on Sat Oct 21 00:43:00 2006