Chapter 10 ii
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Chapter 10 ii Presentation Transcript

  • 1. Chapter 10 – Section I
  • 2. The continental drift hypothesis – continents have moved slowly to their current locations
  • 3. All continents were once connected as one large landmass now called Pangaea
  • 4. The land mass broke apart, and the continents drifted to their present positions.
  • 5. Evidence for continental drift
  • 6. Puzzle-like fit of the continents
  • 7. Similar fossils have been found on different continents
  • 8. Remains of warm-weather plants in Arctic areas and glacial deposits in tropical areas suggest that continents have moved
  • 9. Similar rock structures are found on different continents.
  • 10. At first, continental drift was not accepted because no one could explain how or why continents had moved
  • 11. Chapter 10 Section II Seafloor Spreading
  • 12.
    • Using sound waves, scientists discovered a system of underwater mountain ranges called the mid-ocean ridges in many oceans.
  • 13. In the 1960s, Harry Hess suggested the theory of seafloor spreading to explain the ridges
  • 14. 1) Hot, less dense material below Earth’s crust rises towards the surface at the mid-ocean ridges.
  • 15. 2) Then, it flows sideways, carrying the seafloor away from the ridge.
  • 16. 3) As the seafloor spreads apart, magma moves up and flows from the cracks, cools, and forms new seafloor
  • 17.  
  • 18. Evidence for seafloor spreading
    • Youngest rocks are located at mid-ocean ridges.
    • Reversals of Earth’s
    • magnetic field are
    • recorded by rocks
    • in strips parallel to ridges.
  • 19. Section III – Theory of Plate Tectonics
    • Plate movements
  • 20. 1) Earth’s crust and upper mantle are broken into sections
  • 21. 2). The sections, called plates, move on a plasticlike layer of the mantle
  • 22. 3) The plates and upper mantle form the lithosphere.
  • 23. 4. The plasticlike layer below the lithosphere is called the asthenosphere
  • 24. Plate Boundaries
    • 1. Plates moving apart – divergent boundaries
  • 25. Movie
  • 26.
    • 2. Plates moving together – convergent boundaries
  • 27.
    • Denser plates sink under less dense plates.
  • 28.
    • Newly formed hot magma forced upward forms volcanic mountains.
  • 29.  
  • 30. Plates Collide
    • Plates crumple up to form mountain ranges
  • 31.
    • Earthquakes are common.
  • 32.
    • Plates slide past – called transform boundaries, sudden movement can cause earthquakes.
  • 33.  
  • 34.
    • Convection inside Earth – The cycle of heating, rising, cooling, and sinking of material inside Earth is thought to be the force behind plate tectonics.
  • 35. Features caused by plate tectonics
    • 1) Fault and rift valleys.
  • 36.
    • 2) Mountains and Volcanoes
  • 37.
    • Strike-slip faults – cause of earthquakes
  • 38. Testing for plate tectonics – scientists can measure movements as little as 1 cm per year