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Plate tectonics


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Plate Tectonics IGCSE Geography

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Plate tectonics

  1. 1. PLATE TECTONICS IGCSE GRADE 10 GEOGRAPHY REVISION The Natural Environment Geography
  2. 2. Earth’s Structure  Crust  Continental Plate  Forms land, lighter than the oceanic plate (granite)  Oceanic Plate  Below ocean, dense heavy rock (basalt)  Mantle  Outer Core  Inner Core
  3. 3.  The Earth is made up of the inner and outer core, the mantle and the crust.  There are two types of plates. The continental and the oceanic plate. The continental plate is mostly above the ocean, forming land. It is between 25 and 100 kilometers and is mostly made of granite, a lighter rock than basalt. The oceanic plate is mostly below the ocean. It is mainly made of basalt between 5 and 10 kilometers thick. Basalt is a denser and heavier rock and sinks below the continental plate.
  4. 4. The Convection Currents Around the solid core of the earth is a layer of molten magma called the mantle. Convection currents flow through this layer which move plates floating on the mantle.
  5. 5. The Earth’s Tectonic Plates Nazca Plate South American Plate African Plate Pacific Plate North American Plate Eurasian Plate Antarctic Plate Indo-Australian Plate
  6. 6. Plate Boundaries  3 Types of Plate Boundaries  Constructive  Divergent plate margin  Destructive  Convergent plate margin  Collision plate margin  Conservative plate margin
  7. 7. Constructive boundary:  Plates move apart  Volcanoes formed as magma wells up to fill the gap  New Crust made  In oceans, oceanic ridges are formed  Ex: Mid-Atlantic ridge Constructive plate boundaries. They occur when two plate boundaries move apart. The magma wells up the gap and forms new crust, this forms volcanoes.
  8. 8. Destructive boundary: Convergent  Oceanic and continental plates move together  Oceanic plate forced under continental plate  Friction: earthquakes and melting of the plate  Magma rises up through cracks breaks onto surface  Ex: boundary between Nazca and South American Plates Convergent destructive boundary. This occurs when oceanic and continental plates move together. As the oceanic plate is forced under the lighter continental plate, friction causes the melting of the oceanic plate and earthquakes. Magma rises us through the cracks onto the surface to form volcanoes.
  9. 9. Collisional boundary:  2 continental plates  Neither plate is forced under the other  Therefore, both are forced up  Fold-mountains formed  Ex: Himalayas Collisional destructive boundary. When two continental plates collide, neither of them is forced down and therefore are both forced up to form fold-mountains.
  10. 10. Conservative boundary:  When plates move past each other in opposite direction  Friction is eventually overcome and the plates slip past each other in a sudden movement  This causes an earthquake  Ex: San Andreas Fault, California Conservative boundary. When plates move past each other in opposite direction or a different speeds, tension is built up in the rocks and released in an earthquake when the friction is
  11. 11. Earthquakes  Seismometers record earth movements  An Earthquakes is a sudden shockwave (a rapid flow of energy) caused by rocks under stress due to the movement of the earth’s plates  The Richter scale is used to measure the strength of earthquakes  Example: Earthquake in Haiti: Case Study in Notes for further information
  12. 12. Volcanoes  A volcano is an opening in the earth’s crust allowing magma, ash and gases from the mantle to reach the surface  2 types of volcanoes  Composite  Shield
  13. 13. Tsunamis  A tsunami is a sea wave caused by the displacement of large quantities of water  Can be caused by earthquakes trigged by the movement of the crust under the ocean
  14. 14. Bibliography  graphy/physical_processes/plate_tecto nics/revision/1/