Continental Drift

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 Force for Drifting

  • Movement responsible for the drifting.
  • pole-fleeing force - relates to the rotation of the earth
  • Tidal force – is due to the attraction of the moon and the sun that develops tides in oceanic water.
Continental Drift
  • It was Alfred Wegener—a German meteorologist who put forth a comprehensive argument in the form of “the continental drift theory” in 1912
  • PANGAEA – All Earth
  • PANTHALASSA - Mega-Ocean
  • Pangaea, began to split form Laurasia and Gondwanaland forming the northern and southern.
  • Laurasia and Gondwanaland continued to break into various smaller continents that exist today
  • Assumption - SIAL is floating over SIMA without residence.
  • Forces
  • Tidal forces (Gravitational pull of sun and moon) for westward Movement.
  • Forces of Buoyaney & Different gravitational Force (for equator Movement).
Evidence in Support of the Continental Drift
  1. The Matching of Continents (Jig-Saw-Fit)
    • Best fit of the Atlantic margin was presented by Bullard in 1964. It proved quite perfect.
  2. Rocks of Same Age Across the Oceans
    • The belt of ancient rocks of 2,000 million years from Brazil coast matches with those from western Africa.
  3. Tillite
    • It is the sedimentary rock formed out of deposits of glaciers.
    • Resemblance of the Gondawana-type sediments clearly demonstrates that these landmasses had remarkably similar histories.
  4. Placer Deposits
    • Gold deposits of the Ghana are derived from the Brazil plateau when the two continents lay side by side.
  5. Distribution of Fossils
    • When identical species of plants and animals adapted to living on land or in fresh water are found on either side of the marine barriers,
Post-drift Studies
Particularly, the information collected from the ocean floor mapping provided new dimensions for the study of distribution of oceans and continents.
  1. Convectional Current Theory.
    • Currents are generated due to radioactive elements causing thermal differences in the mantle portion.
  2. Mapping of the Ocean Floor
  3. Ocean Floor Configuration
    • Continental Margins - continental shelf, continental slope, continental rise and deep-oceanic trenches.
    • Abyssal Plains – the continental sediments that move beyond the margins get deposited.
    • Mid-Oceanic Ridges - This forms an interconnected chain of mountain system within the ocean
  4. Distribution of Earthquakes and Volcanoes

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