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Plate tectonics

Plate tectonics. By: Cpt. Justin Tew, Albert Webb, and Austin Denning. Contents. General tectonics How plates move Convection currents Seafloor spreading Subduction zone Trenches isostasy Boundaries Divergent boundary Transform boundary Convergent boundary. General tectonics.

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Plate tectonics

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  1. Plate tectonics By: Cpt. Justin Tew, Albert Webb, and Austin Denning

  2. Contents • General tectonics • How plates move • Convection currents • Seafloor spreading • Subduction zone • Trenches • isostasy • Boundaries • Divergent boundary • Transform boundary • Convergent boundary

  3. General tectonics • Plates are slabs of land floating in the mantle. • There are 7 different plates : the names are Eurasian, North American, South American, Pacific, African, and Australian. • Plates slide on mantle, very rarely bumping into each other. • If plate bump into each other it will either cause an earthquake or form a mountain.

  4. Convection currents Convection currents are caused by the minerals at the bottom of mantle rising heating and rising and cooling and sinking and repeat

  5. Mid-ocean ridges A mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, formed by plate tectonics.

  6. Sea floor spreading sea-floor spreading is the process in which the ocean floor is extended when two plates move apart. As the plates move apart, the rocks break and form a crack between the plates. Earthquakes occur along the plate boundary. Magma rises through the cracks and seeps out onto the ocean floor like a long, thin, undersea volcano.

  7. Subduction zone A convergent plate boundary where one plate subducts beneath the other, usually because it is denser. The western coast of South America is roughly coincident with a subduction zone in which a plate consisting of ocean floor is subducting beneath the continental mass of South America.

  8. Trenches and isostasy • Trench is a fault under the ocean • Trenches can be twice as deep as a mountains height. • Mariana trench is as deep as 3 Mt. Everest stacked on top of each other. Isostasy is balance which sections of the earth's lithosphere (whether continental or oceanic) are thought ultimately to achieve when the vertical forces upon them remain unchanged. The lithosphere floats upon the semifluid asthenosphere below.

  9. boundaries • A boundary is when a plate and another plate meet. • There are 3 types of boundaries: Divergent, Transform, and Convergent • See following slides and make a note of the slide types and how they meet.

  10. Divergent boundaries • Divergent boundaries are when the plates pull away from each other. • Notice the DIV in the name Divergent, div means divide, which means pull away.

  11. Transform boundaries • Transform boundaries rub against each other • These boundaries often cause faults, which are giant cracks in the earths crust.

  12. Convergent boundaries • Convergent boundaries are when one plate is forced under the other one. • These boundaries are mostly under the ocean. • Take note of the picture.

  13. Video!!! • http://www.youtube.com/watch?v=hqp_TbIZU64

  14. Conclusion • Plates are floating pieces of land floating on mantle. • There are 7 major plates. • Boundaries are when plates meet. • There are 3 types of boundaries. • Any questions???

  15. REFRENCES • Video http://www.youtube.com/watch?v=hqp_TbIZU64 • http://answers.yahoo.com/question/index?qid=20081029213510AAOAkFw • http://www.platetectonics.com/

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