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Our Restless Earth

Our Restless Earth. Plate Tectonics. Continental Drift Theory…. Alfred Wegener , 1912 Pangaea Super continent that contained all the land mass in the world 180 million years ago Pangaea broke up and slowly drifted apart. Evidence for Continental Drift.

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Our Restless Earth

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  1. Our Restless Earth Plate Tectonics

  2. Continental Drift Theory… • Alfred Wegener, 1912 • Pangaea • Super continent that contained all the land mass in the world • 180 million years ago Pangaea broke up and slowly drifted apart

  3. Evidence for Continental Drift... • Jigsaw puzzle fit of South America and Africa • Similar fossils found on east coast of South America and west coast of Africa • Glacial deposits found near equator

  4. What is Plate Tectonics? A Theory that explained continental drift • Earth is made up of about 20 rigid plates (12 major - 8 minor) • As the plates shift around, land masses move in relation to each other

  5. Why do Plates Move? • Theory: • The solid plates (lithosphere) float on the molten rock of the asthenosphere • Convection currents from deep inside the earth circulate the molten rock (magma) • The plates are dragged and pushed along with the magma

  6. What is a Plate Boundary? A PLATE BOUNDARY IS The region where TWO TECTONIC plates meet

  7. What are the Types of Plate Boundaries? • Spreading Boundaries(YELLOW) : (Diverging Boundaries) • Where 2 plates move apart • Colliding Boundaries(RED) : (Converging Boundaries) • Where 2 plates bump into each other • Transform Boundaries(PINK) : (Strike-Slip Fault Boundaries) • Where 2 plates rub against eachother

  8. What Events Occur at Plate Boundaries? • Spreading (Diverging) Boundaries • Sea Floor Spreading - Volcanic activity here produces: • New crust material • Mid-Ocean Ridges consisting of: • Ridges (mountains) • Rifts (valleys)

  9. Colliding (Converging) Boundaries • Subduction - • Heavier oceanic crust is pushed below lighter continental crust • The result : • Deep ocean trenches • Volcanic mountain ranges • Buckling - • Lighter crust is crumpled or folded • Produces mountain ranges

  10. Transform Boundaries(Strike-Slip Fault Boundaries) • Result in faults or cracks in the earth’s crust • Earthquakes are likely to be found here

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