Post on 01-Jan-2016
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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.
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 Earth’s crust is moving around not just the continents
• Crust is the outermost layer of Earth’s 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