The Theory of Plate Tectonics

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The Theory of Plate Tectonics
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• The lithosphere is divided into separate sections
  called plates.
• The plates carry continents and ocean crust or
  both.

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A Theory of Plate Motion

• J.Tuzo Wilson, a Canadian scientist, combined sea
  floor spreading, Earths plates and continental
  drift into a single theory.
• Scientific theory is a well tested concept that
  explains a wide range of observations.
• Plate tectonics is a theory that states the
  pieces of Earths lithosphere are in constant
  slow motion driven by convection currents in the
  mantle.

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• Plate Tectonic Theory explains the formation,
  movement, and subduction of Earths plates.
• PLATE BOUNDARIES
• The edges of different pieces of the lithosphere
  meet at lines called plate boundaries.
• Faults- breaks in Earths crust, form at
  boundaries.

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• There three types of plate boundaries Transform,
  Divergent, and Convergent.

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Transform Boundaries

• A place where two plates slip by each other,
  moving in opposite directions.
• Earthquakes occur at these boundaries.

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Divergent Boundaries

• The place where two plates move apart or diverge.
• When a divergent boundary occurs on land a Rift
  Valley, a deep valley, occurs.

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Convergent Boundary

• The place where two plates come together, or
  converge.
• When two plates collide, the plate that is most
  dense will sink beneath the other.

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The Continents Slow Dance

• The plates move from about one to ten centimeters
  a year.
• The North American and the Eurasian plates move
  about 2.5 cm. a year.