the theory of plate tectonics
DESCRIPTION
The Theory of Plate Tectonics. 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. Tectonic Plates. A Plate Boundary is the place where two plates meet. - PowerPoint PPT PresentationTRANSCRIPT
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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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