Plate%20Boundaries%20and%20Plate%20Tectonics

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Plate Boundaries and Plate Tectonics

• By Mike Brady, Joe Fassel, Liz Alessi, Brittany
  Spalding, Josh Minnich

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Plate Boundaries

• -a fracture that separates one plate from another

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3 different types

• Divergent boundary
• Convergent boundary
• Transform boundary

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Divergent

• Forms when two plates move apart from each other,
  then the underlying asthenosphere oozes upward to
  fill the gap between the separating plates.
• Plates Involved
• Ocean-Ocean? Ex) Mid-Atlantic Ridge
• Continent- Continent? Ex) East African Rift

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Convergent

• Two lithospheric plates move toward each other, 2
  plates of different densities come together and
  the denser one sinks beneath it.
• Plates Involved
• Ocean-Ocean? Ex) Western Aleutians
• Ocean-Continent? Ex) Andes
• Continent-Continent? Ex) Himalayas

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Transform

• This forms when two plates slide horizontally
  past on each other as they move in opposite
  directions.
• Plates Involved
• Ocean-Ocean? Ex) East Pacific Rise
• Continent-Continent? Ex) San Andreas fault

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Short Term Climate Change

• Climate change can occur rapidly in a few ways
  due to plate tectonics.
• Plate tectonics can cause waterways to close or
  mountains to form.
• This can cause changes in air currents and water
  currents, which in turn causes climate changes.

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Long Term Climate Change

• Plate Tectonics can cause extreme changes in
  climate over a geologically long period of time.
• This occurs when a continent shifts far distances
  and therefore changes its latitude relative to
  the equator and the poles.

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Sea Floor Spreading

• Sea floor spreading causes the global climate to
  change in two ways.
• When the sea floor spreads slowly the Mid-Ocean
  ridge system is relatively narrow.
• This displaces a relatively small amount of
  water, and exposes a large amount of marine
  limestone which, during the process of weathering
  decreases the amount of CO2 in the atmosphere,
  and decreases the global temperature.

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Sea Floor Spreading Cont.

• When the sea floor spreads rapidly the Mid Ocean
  Ridge system is wider, and displaces a larger
  amount of water.
• This raises sea level and in turn cuts down the
  amount of exposed marine limestone.
• Which in turn reduces the amount of CO2 removed
  through weathering, and increases the global
  temperature.

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Affect of More Lands and at Higher Latitudes

• Alter ocean currents and therefore heat transport
• Alter global atmospheric circulation
• More glaciers over land, higher albedo, cooler
  temps

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Sources

• http//apollo.lsc.vsc.edu/classes/met130/notes/cha
  pter18/plate_tech.html
• Thompson Turk, Earth Science and the
  Environment,3rd Edition.