7.3 Plate Tectonics

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7.3 Plate Tectonics
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The Theory of Plate Tectonics

• Plate Tectonics the theory that explains how
  large pieces of the Earths outermost layer
  called tectonic plates, move and change shape.

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Tectonic Plate Boundaries

• Boundary a place where tectonic plates touch.
• There are three different types of boundaries
• Convergent
• Divergent
• Transform

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Convergent Boundaries

• Convergent Boundary the boundary formed by the
  collision of two lithospheric plates.
• There are three different types of convergent
  boundaries
• Oceanic Oceanic
• Oceanic Continental
• Continental - Continental

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Oceanic Oceanic Plate Boundaries

• http//geology.com/nsta/convergent-boundary-oceani
  c-oceanic.gif

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Oceanic Oceanic Convergent Boundary

• Normally one of the oceanic plates will subduct
  below the other.
• The older plate is usually the one that gets
  pushed down because it has a greater density.
• Eventually magma is formed because of the
  increased pressure causing volcanoes to form over
  the top of the layer.
• Eventually the volcanoes will peak out of the
  water and if they continue to grow the will form
  island chains.
• Ex. Japan

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Oceanic Oceanic Plate Boundary
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Continental Oceanic Plate Boundaries Mt. Adams

• http//geology.com/nsta/convergent-boundary-oceani
  c-continental.gif

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Continental Oceanic Plate Boundaries

• When the two plates collide the less dense
  continental plate will rise up on top of the more
  dense oceanic plate.
• The subducted plate will become molten due to the
  increase in temperatures.
• The magma will then rise because it is less dense
  than the mantle that is surrounding it.
• As the magma rise it will cause volcanic and
  earthquake activity.

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Continental Oceanic Plate Boundaries
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Continental Continental Plate Boundaries

• http//geology.com/nsta/convergent-boundary.gif

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Continental Continental Plate Boundaries

• The process in which two land masses collide
  together. Normally the landmass that is the least
  dense will subduct only slightly below the other.
• Mountains will form because the two colliding
  plates are very light in comparison to the
  mantle.

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Divergent Plate Boundaries

• Divergent Boundary the boundary between two
  tectonic plates that are moving away from each
  other.
• New Sea floor forms at divergent boundaries.
• Mid-ocean ridges is the most common type of
  divergent boundary.

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Divergent Plate Boundaries
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Transform Boundaries

• Transform Boundary The Boundary between
  tectonic plates that are sliding past each other.
• Ex. San Andreas Fault in California.
• One of the few faults that can be visibly seen.
• One of the major causes of Earthquakes.

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Output Pushing and Pulling Mountains

• Draw an example of the five different plate
  boundaries.
• Label and describe what happens at each different
  plate boundary.

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Transform Plate Boundaries
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Plate Summary
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Possible Causes of Tectonic Plate Motion

• Asthenosphere flows very slowly.
• This movement occurs because of the change in
  density within the asthenosphere.
• Density changes because of the outward flow of
  energy within the Earth.
• Hot rock expands and rises.(Less Dense)
• Cool rock contracts and sinks. (More Dense)

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Possible Causes of Tectonic Plate Motion
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Tracking Tectonic Plate Motion

• Tectonic plates move roughly 5cm per year.
• The rate is so slow that it cannot be seen nor
  felt except during an Earthquake.
• Plate movement is tracked by GPS.