Plate Tectonics

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Plate Tectonics

• Objective describe the theory of plate tectonics

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Plate Tectonics

• The crust is embedded into the lithosphere and
  broken into plates

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Plate Tectonics

• Plate tectonics continents are embedded in
  lithospheric plates, as the lithosphere moves on
  the asthenosphere, the continents also move.

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What makes plates move?

• The heat of the mantle forms a process called
  Convection.
• As the magma in the mantle that is close to the
  core heats up, it rises towards the surface of
  the Earth.
• When it gets near the surface it cools and sinks
  back down again, gets re-heated and the process
  repeats

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Why do plates move?

• This movement of magma into the asthenosphere is
  what causes the lithosphere and plates to move!

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Develop a Theory

• Come up with a theory to explain the next 3
  pieces of evidence

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Evidence 1

• The continents look like they fit together.

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Evidence 2

• Some fossils are only found in isolated parts of
  the world all the way across the oceans.

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Evidence 3

• Rock layers and structures match in continents
  separated by the oceans.

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• What does this evidence support about how the
  world looked 250 million years ago?
• Why/What caused continents to move?

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Continental Drift Theory

• Continental drift theory is the movement of the
  continents
• It states that 250 million years ago the
  continents were one super continent and have
  since drifted apart
• The super continent is called Pangaea

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The Evidence

• While we cannot go back 250 million years and
  observe the position of the continents (since we
  dont have a time machine), here is the evidence
  that supports continental drift theory

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Evidence for continental drift

• The continents appear to fit together
• 2. Fossils of the same animals and plants are
  found on different continents
• 3. Matching rock formations are found on
  different continents

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Stop!
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Plate Boundaries

• The edge of a plate where it meets another plate
  is called a Plate Boundary
• There are three things that can happen at plate
  boundaries
• http//www.classzone.com/books/earth_science/terc/
  content/visualizations/es0804/es0804page01.cfm?cha
  pter_no08

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1 Plates can move apart- Divergent

• Animation!
• http//scign.jpl.nasa.gov/learn/plate4.htm

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Divergent

• This happens at Mid-ocean ridges, it causes the
  sea to get wider. (Sea-Floor Spreading)
• Causes earthquakes, volcanoes, rift valleys,
  ridges.
• Ex the Mid-Atlantic ridge, the East Pacific Rise

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2 Plates can slide past each other- Transform
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Transform

• Plates slide past each other
• Causes earthquakes
• Ex San Andreas Fault, North Anatolian Fault
• http//www.classzone.com/books/earth_science/terc/
  content/visualizations/es0804/es0804page01.cfm?cha
  pter_no08

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3) Plates move towards each other- Convergent

• Three types of convergent boundaries-
• Ocean-ocean subduction
• Ocean-continent subduction
• Continent-continent collision
• Subduction means one plate diving under another
  plate

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A Ocean-ocean subduction

• Occurs deep in the ocean.
• Causes deep-sea trenches, earthquakes, volcanic
  island arcs
• Ex Indonesian Islands

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A Ocean-ocean subduction

• PICTURE!

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B Ocean-continent subduction

• An oceanic plate dives under a continental plate
• Causes deep-sea trenches along continents,
  earthquakes, volcanoes on the edge of a continent
• Ex Western coast of South America
• http//www.classzone.com/books/earth_science/terc/
  content/visualizations/es0804/es0804page01.cfm?cha
  pter_no08

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B Ocean-continent subduction

• Picture!

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C Continent-Continent Collision

• Two continents run in to each other.
• Causes mountains to rise (mountain building),
  earthquakes
• Ex Himalayas- India crashed in to Asia!
• http//www.classzone.com/books/earth_science/terc/
  content/visualizations/es0808/es0808page01.cfm?cha
  pter_no08

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C Continent-Continent Collision

• http//www.classzone.com/books/earth_science/terc/
  content/visualizations/es0808/es0808page01.cfm?cha
  pter_no08

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Questions (due Monday!)

• Section review 8.2- pg 179
• 1 Explain how new oceanic crust is formed at a
  divergent boundary.
• 2 Describe two different types of subduction
  boundaries. Use the plate boundary map on pages
  712-713 to identify an example of each type.
• 3 Describe what happens at a collision boundary.
  Identify a collision boundary on the map on
  pages 712-713.
• 4 Describe the movement of plates at a transform
  boundary, and give some examples.
• 5 What types of plate boundaries are not shown
  in the diagram on pages 174-175?
• 6 Critical Thinking Explain how the densities
  of oceanic crust and continental crust influence
  what happens when an oceanic plate converges with
  a continental plate.
• 7 Geography In 2001, a large earthquake related
  to the movements of two plates occurred about 20
  kilometers northeast of Olympia, Washington. Use
  the map on pages 712-713 to identify the plates
  and the type of boundary they share.