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Tectonic Plates

Tectonic Plates

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Tectonic Plates

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  1. Tectonic Plates

  2. Plate Tectonics The lithosphere (crust and upper part of mantle) is broken into 15 pieces called tectonic plates! The places where the tectonic plates meet each other are called plate boundaries!

  3. CRUST!!!!! CONTINENTAL CRUST OCEANIC CRUST Underlies oceans Thinner than continental crust Denser • Underlies the land • Thicker than oceanic crust • Less dense

  4. PLATE BOUNDARY

  5. The plates are constantly moving in one direction or another!

  6. Why do Plates Move? Scientists now know that the plates move because of Convection Currents in the mantle which push the plates.

  7. Well how exactly do convection currents work in the mantle?? Basically the asthenosphere (which is the layer below the lithosphere) has plasticity. Plasticity is the ability for the weak solid to flow like a liquid.

  8. All this plate movement creates three types of plate boundaries. Divergent Boundaries 2. Convergent Boundaries 3. Transform Boundaries

  9. Divergent Boundary • Also called a spreading boundary because the plates are moving apart • When the plates separate, magma is forced up through the crack, which creates new land as it cools. MAGMA RISING NEW LAND FORMED PLATES MOVING APART

  10. Divergent Boundaries • Since divergent boundaries create new land, they are called constructive boundaries. Volcanoes are formed along divergent boundaries!

  11. Sea Floor Spreading • Two oceanic plates are separating • In the ocean, magma rises from below, cools, and creates new sea floor. • Ocean floor is continuously being added and also being moved. It is like a conveyor belt.

  12. Sea Floor Spreading YOUNGEST CRUST OLDEST CRUST

  13. Mid-Oceanic Ridges Underwater mountains formed along divergent boundaries when magma cools

  14. MID ATLANTIC RIDGE

  15. Rift Valley • Two continental plates separating • Great Rift Valley on the continent of Africa. The Arabian Plate is pulling away from the AfricanPlate

  16. Divergent Boundaries are associated with…….. • Volcanoes • Sea floor spreading • Mid-oceanic ridges • Rift valleys

  17. Convergent Boundaries • Also called a colliding boundary because the plates are moving towards each other. • Also called destructive boundary because land is destroyed here • Three types of convergent boundaries • Oceanic-oceanic • Oceanic-continental • Continental-continental

  18. Oceanic- Oceanic Convergent One of the plates will be forced underneath the other plate, creating trenches and volcanos.

  19. Oceanic- Continental Convergence The denser oceanic crust will be subducted underneath the lighter continental crust, creating a trench and volcanoes.

  20. Subduction • Occurs when one plate that is denser meets a lighter plate. • The denser plate is forced underneath and destroyed in the asthenosphere • Creates trenches and volcanoes

  21. Oceanic- Oceanic BoundariesandOceanic- Continental Boundariesare associated with… Subduction Volcanoes Earthquakes Trenches

  22. TRENCH VOLCANOES SUBDUCTION

  23. Continental- Continental Two continental plates meet, begin to buckle and build mountain ranges

  24. Himalayan Mountains

  25. Transform Boundaries The plates slide past each other in opposite direction and are called fractures. Transform Boundaries are associated with earthquakes and volcanoes. Crust is neither lost nor destroyed.

  26. San Andreas Fault

  27. San Andreas Fault Two major Earthquakes during the last century: • 1906 Earthquake destroyed the city. • 1989 Loma Prieta Earthquake was captured on television because the World Series baseball game was about to start.