PLATE TECTONICS (35)

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PLATE TECTONICS (35)
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Plate Movement

• Theory of plate tectonics, Earths crust and part
  of the upper mantle are broken into sections.
• These sections, called plates, move on a
  plasticlike layer of the mantle

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Lithosphere

• Continental Crust part of upper layer of
  mantle Lithosphere
• Plasticlike layer below the lithosphere is called
  the asthenosphere.
• Plates of the lithosphere float and move around
  on the asthenosphere.

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• Divergent Plate Boundary plates move apart. Ex.
  Mid-Atlantic Ridge
• Convergent Plate Boundary two plates colliding.
  Ex. Himalyan Mountains
• Transform Plate Boundary two plates slide passed
  one another in opposite direction. Ex. San
  Andreas Fault

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• Divergent Plate Boundary- creates new crust
• Convergent Plate Boundary- subducts old, dense
  oceanic crust or creates mountains
• Oceanic Continental Plate- Oceanic goes
  underneath continental.
• Continental- Continental- push together and form
  mountains.

Subduction Zone- area where an oceanic plate
subducts, or goes down, into the mantle
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• Subduction zone creates a deep-sea trench where
  one plate bends and sinks beneath the other.
• New magma is forced upward along these plate
  boundaries, forming volcanoes.

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Transform Boundary

• One plate slips past another suddenly,
  earthquakes occur
• San Andreas Fault is an example of Transform
  Plate Boundary.

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Causes of Plate Tectonics

• The cycle of heating, rising, cooling, and
  sinking is called a convection current
• Such convection currents (see arrows) are the
  driving force of plate tectonics.

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Rift Valleys

• Rift valleys and mid-ocean ridges can form where
  Earths crust separates
• Examples of rift valleys are the Great Rift
  Valley in Africa, and the valleys that occur in
  the middle of mid-ocean ridges.

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http//www.youtube.com/watch?vmB2pzhWUaiU