Plate Tectonics

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Plate Tectonics
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Contents

• Plates and an introduction to plate boundaries
• Conservative Plate Boundaries
• Destructive Plate Boundaries
• Constructive Plate Boundaries
• Driving Mechanisms

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Plates

• The Earths surface is divided up into rigid
  plates which move relative to one another
• The plate is the LITHOSPHERE, about 100 km
  thick consisting of the CRUST (oceanic or
  continental) and the UPPERMOST MANTLE.
• Plates are rigid and are conductors of heat.

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Distribution of Plates today
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Plate Boundaries
These are ACTIVE boundaries (across which one
plate moves relative to the other).
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This is not a plate boundary! Its a PASSIVE
CONTINENTAL MARGIN where continental crust thins
into oceanic crust.
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Plate Boundaries
Destructive Margins (plates converge) e.g.
Pacific Rim, Andes Constructive Margins (plates
diverge) e.g. Mid-Atlantic Ridge, East Pacific
Rise) Conservative Margins (plates slide past on
another) e.g. San Andreas Fault.
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Conservative Plate Boundaries

• Sometimes known as TRANSFORM BOUNDARIES
• Crust is neither created nor destroyed.
• Movement is STRIKE-SLIP.

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Slip-stick produces many earthquakes, generally
shallow and with horizontal slips
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Case Study San Andreas Fault
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N.American plate
Pacific Plate