The story of pangea and plate tectonics
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The story of pangea and plate tectonics

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    The story of pangea and plate tectonics The story of pangea and plate tectonics Presentation Transcript

    • The Story of Pangaea & Plate Tectonics Leslie Prohaska Florida State University SCE 5943 Field Lab Internship Dr. Alejandro Gallard September 14, 2009
      • Most people thought that the continents had always been and would always be in the same place
    • A puzzle?
      • But some people noticed that the continents fit together somewhat like a jigsaw puzzle
    • Try this puzzle for fun….
      • Click on Continents map below and you will be taken to the JigZone site. Choose the continents map when the page opens and then see how quickly you can solve the puzzle.
      • Continents map
    • Look at the western side of Africa and the eastern side of South America
    • If you turn South America, and then slide it over It fits right in….
    • Some early ideas
      • In 1858, an American, A. Snider published an article on the origin of the Americas
      • He thought that South America and Africa were once together
      • Snider believed this was the case at the time of Noah’s flood
      • Snider proposed that a huge volcanic event caused the landmass to split
    • Half a century later… this idea continued as continental drift
      • In 1910, an American, F.B. Taylor, discussed the origin of mountains
      • He explained that continental movements that ended in collisions would cause the formation of mountains
    • More scientists joined in…
      • German scientist, Alfred Wegener published The Origin of Continents and Oceans
      • He proposed that the continents had once been joined together in a supercontinent he called Pangaea
      • The continents then pulled apart through a mechanism called continental drift
    • What’s in a name?
      • The word Pangea, or Pangaea, is Greek for “all land”
      • Why do you think he chose this name for the supercontinent?
      • What would you name it? Why?
      • Most of his colleagues didn’t agree with him
      • He couldn’t explain why the continents did not seem to be moving now
      • He couldn’t explain how such huge landmasses moved
    • Wegener’s Evidence
      • Fossils of a particular species of lizard and species of plant were found
      • The same fossils were found in Africa and South America directly across the ocean from each other
      • These species could not have crossed between the continents by swimming
    • More evidence finally came
      • This idea of continental drift was not really excepted until the 1960’s
      • Scientists found evidence that the sea floor was spreading
      • Magnetic stripes found on the sea floor help lead to further development of the theory of plate tectonics
    • So…what happened to Pangaea?
      • About 200 million years ago Pangaea existed
      • Dinosaurs roamed all over the land
      Tethys Sea
      • About 180 million years ago, rifting along an ancient body of water called Tethys Sea broke the supercontinent into a northern land mass called Laurasia and a southern land mass called Gondwanaland
      Tethys Sea
    • More splitting…
      • Then plate movements split Laurasia into North America, Europe, and Asia
      • And Gondwanaland split into South America, Africa, peninsular India and later Australia and Antarctica
      • This also formed the Atlantic Ocean
    • Plate Tectonic Theory
      • Not as simple as core, mantle, & crust
      • Remember, there is a
        • A solid inner core composed mainly of iron alloy
        • An outer core that is hot, liquid, iron
        • A solid mantle that is so hot that all but the uppermost portion of it flows
        • An outer crust which is solid
    • New model
      • Two new divisions
        • Asthenosphere – molten, plastic layer of the mantle
        • Lithosphere – upper part of mantle and crust
      • The solid lithosphere
      • moves over the flowing asthenosphere
    • The Broken Pieces of the Lithosphere
      • The lithosphere is divided into several very large plates which can be divided into smaller plates
    • Boundaries – where the plates meet
      • Divergent, Mid-Atlantic Ridge
      • Convergent, mountain building
        • Subduction Zones
      • Transform Faults
      • San Andreas Fault,
      • lots of earthquakes
    •  
    • Our plates are still moving…
      • Where do you think we will be in 100 million more years?
      • 650-million-years-in-1-min-20-sec
    • References
      • 650 Million Years in 1:20 Minutes. In Numaga.com . Retrieved July 28, 2009, from http://www.numaga.com/index.php/hd/numaga-videos/630-650-million-years-in-120-min
      • Harcourt science grade 6 teacher's edition . (2005). Orlando, FL: Harcourt School Publishers.
      • Inside the earth. Retrieved September 12, 2009, from http://www.enchantedlearning.com/subjects/astronomy/planets/earth/Inside.shtml
      • Prohaska, L. (2009, September 12). Retrieved September 12, 2009, from http://www.jigzone.com/gallery/B72509B7BA.77F4672?z=0
      • Spencer, E. W. (2003). Earth science understanding environmental systems . New York: McGraw-Hill.
    • The End Or is it ...