Plate Tectonics Rock___

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					Plate Tectonics Rock!!!
      Theory of Plate Tectonics
A rigid slab of solid rock is called a plate.

Tectonics is a Greek word meaning “to build”.

The theory of plate tectonics states that the lithosphere is
  broken into several plates that are moving relative to one
  another as they ride on top of hotter, more mobile
  material known as the asthenosphere.
 How Does Plate Tectonics Work?
• The plates ride on top of the asthenosphere due to the
  fact that the elements of the rock in the lithosphere are
  less dense than the elements of the rock in the ductile
  asthenosphere.
• These plates have different types of boundaries with
  each other and each type of boundary has different
  characteristics.
           Divergent Plate Boundaries
•   The first type of boundary is known as a
    divergent plate boundary.
•   Divergent boundaries occur along
    spreading centers where plates are
    moving apart and new crust is created by
    magma pushing up from the mantle.
•   Divergent boundaries create mid-ocean
    ridges, which are underwater mountain
    ranges formed as new crust is created
    from magma rising from the mantle. The
    most famous mid-ocean ridge is called
    the Mid-Atlantic Ridge located between
    Europe and North America which is
    currently ripping apart Iceland.
•   Divergent boundaries also create rift
    valleys. Rift valleys are valleys formed
    when lithospheric plates are pulled apart.
    This is currently occurring in Africa and is
    known as the The Great Rift Valley.
    Volcanoes are often created at these
    sites due to the magma rising up from the
    spreading center.
  Convergent Plate Boundaries
• Convergent boundaries, the next type of plate
  boundary, is where crust destruction occurs.
  This is where two plates collide together.
• There are three different types of convergent
  boundaries. They are called oceanic-continental
  convergence, oceanic-oceanic convergence and
  continental-continental convergence. Different
  processes occur at each of these convergent
  settings.
  Oceanic-Continental Convergence
• Oceanic-Continental convergence
  occurs when a oceanic plate
  collides with a continental plate.
  Due to the differences in density
  between the two plates, the
  oceanic plate subducts, or goes
  under the continental plate,
  creating trenches at the subduction
  zone. The continental plate often
  rises at this same point creating
  mountains and volcanoes like that
  seen on the West Coast of South
  America and the Northwestern
  Coast of the United States.
    Oceanic-Oceanic Convergence
•   Oceanic-oceanic convergence
    occurs when two oceanic plates
    collide and one subducts under
    the other. This causes deep
    trenches in the sea floor. The
    most famous trench caused by
    this type of convergence is called
    The Marianas Trench. This trench
    is deeper than the tallest mountain
    in the world, Mt. Everest. It is over
    2000 meters deeper than Mt.
    Everest is tall.
•   Volcanoes are also formed at
    oceanic-oceanic convergent sites.
    These volcanoes create island
    arcs which is how many of the
    world’s islands formed.
            Continental-Continental
                 Convergence
• The final type of convergence,
  continental-continental
  convergence, is how our
  largest mountains are formed.
• Because continental crust is
  relatively low in density, when
  two continental plates collide,
  they resist downward motion
  and instead push each other
  up, building tall mountains.
  The most famous mountain
  range created by this are The
  Himalayas located in Asia.
    Transform Plate Boundaries
• A transform boundary occurs
  when two plates are sliding
  horizontally past each other.
• Also known as fracture zones,
  they are thought to be
  connections between
  spreading centers and most
  occur underneath the ocean.
• The most famous transform
  boundary is known as The San
  Andreas Fault that runs
  through the length of
  California. This one happens
  to occur on land and not
  underneath the ocean.
             EARTHQUAKES!!!
• Earthquakes occur only in
  the lithosphere layer of the
  Earth along faults.
• Earthquakes typically occur
  at plate boundaries. This
  includes all three
  boundaries: divergent,
  convergent, and transform.
• Which boundary creates the
  biggest earthquakes and
  why?

				
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