Plate Tectonic Theory

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Plate Tectonic Theory
1. What are these things called plates? 2. What
do plates do? 3. What is the evidence for the
existence of plates? 4. How do plates
move?
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What is a Plate?

• A plate is a large section of crust that shifts
  position over time.
• There are typically 7 major plates and several
  other minor plates
• The major plates are the north American, South
  American, Eurasian, Arctic, African, Australian,
  and Pacific plates.

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• Plates

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What do colliding plates do?

• They form convergent boundaries and produce
  mountains, volcanoes, and earthquakes. They pile
  crust or get rid of it.

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What do separating plates do?

• They form divergent boundaries to produce
  earthquakes, rift valleys, and a few volcanoes.
  They form new crust.

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What do sliding plates do?

• They form transform boundaries that produce
  earthquakes, They generally do not form new
  crust or destroy it.

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Boundary Types

• Boundaries are the joints between two or more
  pieces of the crust
• Divergent Boundaries Crusts moving away from
  one another
• Convergent Boundaries Crusts moving toward one
  another
• Transform Boundaries Crusts sliding alongside
  one another

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How do plates move?
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Theory of Plate Tectonics

• Like a broken eggshell
• States that Earths crust is moving around not
  just the continents
• Crust is the outermost layer of Earths body and
  is fragmented
• Crust floats on molten rock

• Molten rock below upper crust has heat currents
  that push crustal rock (convection currents)
• Slab pull and ridge push aid in movement of
  oceanic plates and some continental plates.
• Theory is generally accepted