The Theory of Plate Tectonics

1
The Theory of Plate Tectonics

• Chapter 9, Section 5
• A geological theory stating that pieces of
  Earths lithosphere are in constant, slow motion.
• As plates move they crash together, pull apart
  and grind past each other.
• Each movement along a plate boundary creates a
  different land feature.

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Plate Boundaries

• Transform Boundaries
• Two plates slip by each other
• Crust is not created or destroyed
• Earthquakes occur often

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What drives the plates?
4
Plate Boundaries

• Divergent Boundaries
• Plates move away from each other
• Found in the oceanic and continental crust
• Creates rift valleys
• The mid-ocean ridge is a D.B.

5
Plate Boundaries

• Convergent Boundaries
• Plates come together, collide, crash!
• 3 things can happen depending on the type of
  crust that is colliding.

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1 - Oceanic to Oceanic the more dense plate
will subduct (go under the other).
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2 - Oceanic to Continental the more dense
oceanic crust subducts (goes under)
http//www.wwnorton.com/college/geo/egeo/animation
s/ch2.htm
8
3 - Continental to Continental
builds mountains
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Plate Boundaries

• Demo-
• http//www.wwnorton.com/college/geo/egeo/animation
  s/ch2.htm
• Subduction - http//oceanexplorer.noaa.gov/explora
  tions/03fire/logs/subduction_320.mov