Plate Tectonics

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Plate Tectonics

• Chapter 17

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Plate Tectonics

• Plate tectonics
• Tries to explain the dynamics of plate movement
• Why and how do the plates move
• Heat causes convection currents
• This theory is supported by examining the
  different types of plate boundaries
• Divergent
• Convergent
• Transform

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Plate Tectonics

• Divergent Plate Boundaries
• Magma comes up pushing plates away
• New earth is created
• Rift valley formed on land
• Mid-Ocean Ridge largest divergent boundary
• Iceland only place where Mid-Ocean Ridge is
  above water

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Plate Tectonics

• Divergent Boundary
• Speed of plates
• Continental crust tends to move slower
• New earth is hotter and generally thicker
• Area where magma comes up is hotter than further
  away cooled magma
• Time to cool allows newer earth to settle

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Plate Tectonics

• Divergent Boundary
• Rocks get older as you go away from center
• Rocks get cooler as you go away from center
• This is where new earth is created
• This is called a constructive boundary

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Plate Tectonics

• Convergent Boundaries (2)
• 1. Convergent with subduction (destructive)
• More dense crust subducts under or goes under
• Oceanic Continental
• Oceanic is more dense
• Oceanic subducts
• Area where plates meet great pressure/high
  temperatures
• Lots of friction deep, powerful earthquakes
• Lots of heat melted rock volcanoes

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Plate Tectonics

• Convergent Boundary
• 2. Convergent with collision
• Continent to Continent collision
• No difference in density
• One plate can not subduct
• Mountains are formed here
• Land has no where to go but up
• If there was a sea or ocean, the ocean crust
  subducts until water is all gone ? then collision
  boundary forms

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Plate Tectonics

• Sliding Boundary
• a.k.a.Transform fault/transform boundary
• One plate is sliding horizontally past another
  plate
• San Andreas Fault is most well known
• Earthquakes common at these boundaries

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