Plate Tectonics

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Plate Tectonics
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Plate Tectonics

• Proposed in 1965
• Combination of Wegener Hesss ideas
• Explains that the Earths crust is composed of
  plates that are moved around due to convection
  currents in the mantle

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• This is the cause of plate movements
• Convection Currents - warm magma rises and cooler
  magma sinks

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• 1. Lithosphere the ridged crust and upper part
  of the mantle.
• Brittle
• Breaks very easily
• 2. Asthenosphere the upper mantle
• Hot and plastic-like
• Flows easily

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• The lithosphere is broken up into plates

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• The plates have boundaries
• As they move they affect one another.

Convergent Boundary
Divergent Boundary
Transform Boundary
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Pacific Plate Where the Action is! RING OF
FIRE!
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Hawaiian Hot Spot

• Hawaii is in the middle of the Pacific Plate
• Not on a boundary.

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Magma Rises under Hawaii

• Hot spot is located in the mantle and does not
  move
• The Pacific Plate moves NW over the hot spot
  forming a line of volcanoes.

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• Types of Plate Boundaries

Divergent Boundary
Convergent Boundary
Transform Boundary
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1. Divergent Boundary

• Where two plates that are moving apart from one
  another

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ReviewHow it Works

• Magma pushes up cracks in the crust
• Convection causes the separated plates to move
  and form a rift valley.

AFRICA
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How it Works Step 2

• The valley widens and begins to be filled with
  water. (Red Sea)

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How it Works Step 3

• Eventually an ocean forms
• Example Mid-Atlantic Ridge

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Divergent Boundaries Map
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2. Transform Boundary

• Two plates slide past each other moving in
  opposite directions

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Example San Andreas Fault

• Pacific Plate moves faster than North American
  Plate.

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3. Convergent Boundaries

• two plates are colliding into each other
• Ex Himalayan Mountains

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