Download Plate Tectonic Boundaries PowerPoint From Class

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 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
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