Plate Tectonics

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Plate Tectonics

• A lesson designed for 5th graders
• By
• Meri Koski

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• The theory of plate tectonics is only about 30
  years old. It states that the outer layer of
  Earth (the lithosphere) is broken into 7 plates
  that move in all different directions and at
  varying speeds (2-10cm per year).
• The movement of these plates explains to us
  natural disasters such as volcanoes and
  earthquakes, worldwide distribution of plant and
  animal fossils, and the movement of the mantle
  (the layer below Earths crust).

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• Where two plates meet, it is called a boundary.
  There are three different types of boundaries
  that describe how the plates are moving.
• Convergent Boundaries plates collide
• Divergent Boundaries plates move apart
• Transform Boundaries plates move against each
  other

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Convergent Boundaries

• Plates crash together.
• Continental plate is pushed up and forms
  mountains.
• Oceanic plate sinks below continental plate and
  becomes part of the mantle.
• Earthquakes occur due to the collision of plates.
• Melting oceanic plate and mantle rise up into the
  mountain creating a volcano
• The Himalayan and Appalachian mountains are
  results of plates colliding.

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Divergent Boundaries

• Plates are drifting apart.
• A rift valley forms, which is a deep crack in the
  crust.
• As plates move apart, magma comes up and forms a
  new crust.
• The Mid-Atlantic ridge (the largest mountain
  range) was formed this way and is still growing.

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Transform Boundaries

• Plates slip slide
• The San Andreas Fault is one of the most famous
  transform boundaries
• No mountains or spectacular features form along
  this boundary.
• Tension builds between two plates and releases.
• An earthquake is usually the result of these
  plates moving.

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Our Earth then and now

• About 200 million years ago the land masses on
  Earth were fused together. This single continent
  is known as Pangaea.
• Due to the movement of the mantle (under the
  crust), Pangaea has formed into the Earth we know
  today.

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Evidence that Pangaea did exist

• Fossils are the main form of evidence that our
  continents were once fused.
• Similarities between plant and animal fossils
  have been found on land masses that are very far
  apart today (such as Africa and S. America).
• For example dinosaur fossils and footprints have
  been found in many places around the world. If
  the land masses were separated like they are now,
  how did they get across the oceans?

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• This picture illustrates different dinosaurs and
  plants that have been found all over the world.
• This was possible because of Pangaea!

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Web sites to learn more!

• Check out these web sites to learn more about
  plate tectonics.
• Interactive Plate Tectonic Site
• Plate Tectonics

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Test your knowledge

• Now that you have learned about the theory of
  plate tectonics, you can test what you know!
• Plate Tectonic Quiz 10 question, multiple
  choice quiz on PowerPoint.
• Answers To Quiz Check how much you really
  know.