The Way of Science

UNIT 2

Continental Drift and Plate Tectonics

As you read the following pages, keep in mind that five major concepts are covered. Be sure that you can discuss each of these in class, and answer the specific questions about them at the end of this section on geology. Here are the five major components of the Wegener/Plate Tectonics section:
  1. Old Model
    What was the "old model" for the Earth's formation? That is, what explanation was commonly accepted by academic geologists as a reasonable mechanism for how the Earth formed, and why it had mountains, deep seas, continents, etc. Why does the Earth look the way it does, on a large scale? As part of this first block of material, be sure to understand what predictions can be drawn from the old model. Predictions about radial and lateral movements and about randomness form the bases for Section 2, next.

  2. Wegener's Objections
    The old model produces falsifiable predictions about what we should see when examining the Earth's surface on a large scale. Wegener based his objections to the old model on these predictions. You will be introduced to six or seven of his strongest arguments in the following pages. Be sure you can discuss in detail each of these objections, and how each contradicts predictions of movement and randomness.

  3. Plate Tectonics
    After discussing the flaws in the old model, learn the basics of modern Plate Tectonics, the universally accepted new model. Much of this material is best obtained from your text, plus the film. A brief guide to assist you is also contained in these pages.

  4. Evidence
    Once you have assimilated the material about plates, ridge-rift systems, subduction, etc. from 3, move to the evidence that finally convinced the majority of geologists to abandon the "shrinking apple" model and accept moving plates. Much of the evidence is based on paleomagnetism, and this subject is covered in the following pages, in your text, and in the film.

  5. Resistance
    The last topic is the resistance to the idea of moving plates by most geologists. Why did it take almost 50 years to convince them that they were dead wrong? This material is covered primarily in the pages of this Student Guide.
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