Continental Drift / Plate Tectonics

• The Puzzle
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• Evidence
  • oceanic mapping efforts (1940's - 60's)
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• Explanation
  
• concept of convection to explain continental drift
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• Plates and Movement
  • about 20 major plates moving as distinct units
    
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  • Diverge at mid-ocean (divergence)
    • Pacific & Atlantic Oceans
      
      
  • diverge on continents
    • Red Sea and Africa Rift Valley
      
      
      
  • Lateral movement - plates slide past one another
  • "transform faults" - lateral movement of plates
    • examples:
      
      
      
      
  • Converge where plates slowly collide into one another
  • examples:
    
    
    
• "Subduction" where plates slides under one another
  • associated with volcanoes and earthquakes
    • Pacific Ring of Fire