Plate Tectonics Objective: describe the theory of plate tectonics.
The Theory of Plate Tectonics
description
Transcript of The Theory of Plate Tectonics
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The Theory of Plate Tectonics
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Tectonic Plates
• Tectonic Plates are pieces of lithosphere that move around on the Athenosphere.
• Plates range in size.• Some plates contain
both continental and oceanic crust.
• Plates link like a puzzle.
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Tectonic Plate Boundaries
• A Plate Boundary is the place where two plates meet.
• There are 3 types of boundaries.
1. Convergent2. Divergent3. Transform
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Convergent Plate Boundaries• At Convergent
boundaries two plates collide.
• Three results may happen from the collision.
• The type of plates that collide will determine one of three geographic features.
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Convergent Plate Boundaries1) If two
continental plates collide, a high mountain range may form.
2) The mountain may take many of years to form.
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Convergent Plate Boundaries
3) When a plate of oceanic lithosphere collides with a plate of continental lithosphere, the denser oceanic lithosphere sinks, or subducts beneath the less dense continental crust.
4) This process is called subduction.5) Subduction may cause a chain of volcanoes to form parallel
to the fault.
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5) When two oceanic plates collide, the denser of the two will submerge.
• A series of volcanic islands called island arc may form parallel to the fault.
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Divergent Plate Boundaries• Where two tectonic
plates separate.• Some appear on
land.• Most appear on sea
floor.• As plates spread,
magma rises to the ocean floor.
• The magma cools and forms new lithosphere.
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Transform Plate Boundaries
• Two tectonic plates slide past each other.• Most transform boundaries occur in the sea floor at
mid-ocean ridges.• San Andreas Fault in California occurs both on land
and in the ocean.
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San Andreas Fault
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Causes of Tectonic Plate Motion• Heat is transferred
from the Earth’s core through convection.
• When rock is heated, it becomes less dense and moves towards the surface. At the surface, cooler dense rock tends to sink thru subduction.
• Convection currents are formed all over the mantle, causing plates to move.
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Tracking Tectonic Plate Motion
• Plates move so slow that they are measured in centimeters per year.
• Scientists use GPS and satellites to measure exact distances.
• Scientists use sea floor spreading to measure ocean plates.
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