Naturalists at Large: Plate tectonics

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Naturalists at Large Plate Tectonics Slide Show

Naturalists at Large Plate Tectonics Slide Show

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  • 1. Theory of Plate Tectonics Plate Tectonics Plate Boundaries Causes of Plate Tectonics
  • 2. Plate Tectonics
  • 3. What is Plate Tectonics• The Earth’s crust and upper mantle are broken into sections called plates• Plates move around on top of the mantle like rafts
  • 4. What is the Lithosphere?• The crust and part of the upper mantle = lithosphere –100 km thick –Less dense than the material below it so it “floats”
  • 5. What is the Asthenoshere?• The plastic layer below the lithosphere = asthenosphere• The plates of the lithosphere float on the asthenosphere
  • 6. 2 Types of Plates• Ocean plates - plates below the oceans• Continental plates - plates below the continents
  • 7. Plate Boundaries
  • 8. Divergent Boundaries• Boundary between two plates that are moving apart or rifting • RIFTING causes SEAFLOOR SPREADING
  • 9. Features of Divergent Boundaries• Mid-ocean ridges• rift valleys• fissure volcanoes
  • 10. Convergent Boundaries• Boundaries between two plates that are colliding  • There are 3 types…
  • 11. Type 1• Ocean plate colliding with a less dense continental plate• Subduction Zone: where the less dense plate slides under the more dense plate• VOLCANOES occur at subduction zones
  • 12. Andes Mountains, South America
  • 13. Type 2• Ocean plate colliding with another ocean plate• The less dense plate slides under the more dense plate creating a subduction zone called a TRENCH
  • 14. Aleutian Islands, Alaska
  • 15. Type 3• A continental plate colliding with another continental plate• Have Collision Zones: –a place where folded and thrust faulted mountains form.
  • 16. Transform Fault Boundaries• Boundary between two plates that are sliding past each other• EARTHQUAKES along faults
  • 17. San Andreas Fault, CA
  • 18. Causes of Plate Tectonics
  • 19. Convection Currents• Hot magma in the Earth moves toward the surface, cools, then sinks again.• Creates convection currents beneath the plates that cause the plates to move.