Continental Drift & Plate Tectonics

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  • Yet still it moves! (mu-ov-ay)

  • Introductory textbook. Earth sciences are now like physics?
  • Earth was more violent in the past

  • Evidence for contraction? Cracking such as this in Iceland
  • By 1904 ...


  • Worked in Grand Canyon area
  • Mesozoic: 251 - 65 mybp; problem to solve: similarity of S Am and African fauna / Cynognathus / Mesosaurus (FW not Marine) / Glossopteris
  • Mesozoic: 251 - 65 mybp; problem to solve: similarity of S Am and African fauna / Cynognathus / Mesosaurus (FW not Marine) / Glossopteris
  • Mesozoic: 251 - 65 mybp; problem to solve: similarity of S Am and African fauna / Cynognathus / Mesosaurus (FW not Marine) / Glossopteris
  • Mesozoic: 251 - 65 mybp; problem to solve: similarity of S Am and African fauna / Cynognathus / Mesosaurus (FW not Marine) / Glossopteris
  • Mesozoic: 251 - 65 mybp; problem to solve: similarity of S Am and African fauna / Cynognathus / Mesosaurus (FW not Marine) / Glossopteris
  • Explained using land bridge / approx 1750 miles … and no trace of the landbridge /How did it sink if it was lighter? / Hidden continent?? / Also fauna of Antarctica, India & Australia!!!!
  • Pioneered the use of weather balloons / Disappeared with a companion. Body found the next year.

  • Work was a unification of geophysics, geology and geography / Translated in 1922




  • Shared uplifts
  • These are just the idea of isostacy.
  • #3 had been held for a long time
  • LHS noticed fit of continents / RHS had a theory of drift due to geological forces / Wegener only learned of these after his theory was in place.


  • Also see this with present day earthworms
  • Contiguous mountain ranges
  • Paleoclimate only makes sense – evidence of glaciers

  • But what was the mechanism?

  • In short, drift was a likely but unproven hypothesis. Response in US was different - we’ll see why



  • doo tooey
  • Unconvincing - how not to write a scientific sentence
  • Arthur Holmes

  • No one paid any attention. / It wasn’t until the after WW2 that evidence began to accumulate.
  • sonography and magnetometers were products of hunt for submarines! / seismographs were installed to monitor underground nuclear tests!










  • It’s the plates that move, not the continents!
  • a rift valley in iceland / the bridge (built in 2002) will actually be slowly ripped apart ~ 4cm per year


  • divergent plate boundary: ridges leading to seafloor spreading
    convergent plate boundary: subduction @ trenches often with volcanic island arcs on landward side
    mountains forming (e.g. Rockies and Andes) where continent is riding over a subduction zone.
















  • Evidence for ... similarities of pattern and form
  • Evidence for ... quantifiable geophysical evidence; A new kind of evidence that was dependent on Cold War technologies.

  • over CD


  • scientists and historians - effect of Kuhn???




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