1. Plate Tectonics 22.4

2. Theory that explains the formation and movement of Earth’s plates Theory that explains the formation and movement of Earth’s plates

3. Continental Drift Theory put forth by Alfred Wegener that hypothesized that continents looked liked they fit together like pieces of a puzzle Theory put forth by Alfred Wegener that hypothesized that continents looked liked they fit together like pieces of a puzzle One large supercontinent was formed called Pangaea “all land” One large supercontinent was formed called Pangaea “all land” Pangaea’s eventual split is called continental drift, powered by sea floor spreading Pangaea’s eventual split is called continental drift, powered by sea floor spreading

4. Mid Ocean Ridge In the 1950’s, sonar was used to map the sea floor In the 1950’s, sonar was used to map the sea floor Mountains were discovered Mountains were discovered The mid ocean ridge is the Earth’s longest mountain chain The mid ocean ridge is the Earth’s longest mountain chain Alongside it, runs a deep valley Alongside it, runs a deep valley

5. Mid Ocean Ridge

6. Formation of Oceanic Crust In the crack along the mid ocean ridge, magma rises to the surface In the crack along the mid ocean ridge, magma rises to the surface As it cools, it gets pushed aside by new magma As it cools, it gets pushed aside by new magma Older crust gets pushed farther and farther apart and the sea floor spreads Older crust gets pushed farther and farther apart and the sea floor spreads

7. Sea Floor Spreading

8. Subduction When oceanic plates collide with continental plates, the oceanic plate sinks below it because it is denser When oceanic plates collide with continental plates, the oceanic plate sinks below it because it is denser Oceanic plate is destroyed Oceanic plate is destroyed

9. Subduction

10. Theory of Plate Tectonics Movement of the plates based on the convection of the mantle Movement of the plates based on the convection of the mantle Heat from the core and radioactive decay are two engines that drive plate movement Heat from the core and radioactive decay are two engines that drive plate movement

11. Plate Boundaries Divergent: plates are pulling apart Divergent: plates are pulling apart Convergent: plates are pushing together Convergent: plates are pushing together Transform: plates are sliding side by side Transform: plates are sliding side by side

12. Divergent

13. Convergent

14. Transform

15. Mountain Building Mountains form along plate boundaries Mountains form along plate boundaries Convergent: Himalayas, Andes, Swiss Alps Convergent: Himalayas, Andes, Swiss Alps Divergent: Iceland Divergent: Iceland

16. Essential Questions What is the theory of plate tectonics? What is the theory of plate tectonics? What evidence supports plate tectonics? What evidence supports plate tectonics? How is rock in the ocean formed? How is rock in the ocean formed? What force powers the movement of the continents? What force powers the movement of the continents? Describe the three ways in which the plates move along plate boundaries. Describe the three ways in which the plates move along plate boundaries.

17. References http://www.platetectonics.com/book/images/Midoceanridge.jpg http://www.platetectonics.com/book/images/Midoceanridge.jpg http://www.platetectonics.com/book/images/Midoceanridge.jpg http://library.thinkquest.org/17457/platetectonics/seafloor.jpg http://library.thinkquest.org/17457/platetectonics/seafloor.jpg http://library.thinkquest.org/17457/platetectonics/seafloor.jpg http://www.whoi.edu/annualreport02/images/scihigh_subduction_ en.gif http://www.whoi.edu/annualreport02/images/scihigh_subduction_ en.gif http://www.whoi.edu/annualreport02/images/scihigh_subduction_ en.gif http://www.whoi.edu/annualreport02/images/scihigh_subduction_ en.gif http://www.oceansjsu.com/images/exp5_divergent.GIF http://www.oceansjsu.com/images/exp5_divergent.GIF http://www.oceansjsu.com/images/exp5_divergent.GIF http://www.bgs.ac.uk/discoveringGeology/hazards/earthquakes/i mages/convergentBoundary.jpg http://www.bgs.ac.uk/discoveringGeology/hazards/earthquakes/i mages/convergentBoundary.jpg http://www.bgs.ac.uk/discoveringGeology/hazards/earthquakes/i mages/convergentBoundary.jpg http://www.bgs.ac.uk/discoveringGeology/hazards/earthquakes/i mages/convergentBoundary.jpg http://www.cms.fu-berlin.de/geo/fb/e- learning/geolearning/en/mountain_building/plate_tectonics/media /transform1.jpg http://www.cms.fu-berlin.de/geo/fb/e- learning/geolearning/en/mountain_building/plate_tectonics/media /transform1.jpg http://www.cms.fu-berlin.de/geo/fb/e- learning/geolearning/en/mountain_building/plate_tectonics/media /transform1.jpg http://www.cms.fu-berlin.de/geo/fb/e- learning/geolearning/en/mountain_building/plate_tectonics/media /transform1.jpg