PLATE TECTONICS

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PLATE TECTONICS
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WHY?

• Alfred Wegener
• Noticed similarities in the shoreline of
  continent on both sides of the Atlantic Ocean, he
  then began fitting them together.
• Introduced the hypothesis of continental drift.
• Suggested a supercontinent, called Pangaea
  (meaning "all land"), that broke up millions of
  years ago, slowly moved to their current
  positions, and continue to move today.

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LITHOSPHERE / ASTHENSPHERE
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CONVECTION CURRENTS-Hot magma from the mantle
rises, cools, sinks.-Mantle moves drags
plates along with it.
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PLATES
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DIVERGENT

• DIVERGENT- When two plates move away from each
  other.
• Characteristics
• Mid ocean ridges (underwater mountain ranges)
• Rift Valleys (narrow valleys that form where
  plates separate), Newest rock material (cooling
  magma forms new oceanic crust).

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DIVERGENTEx Seafloor Spreading
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CONVERGENT

• CONVERGENT When two plates collide.
• Characteristics Mountains, most earthquakes,
  Volcanoes, and trenches
• 1.ocean ocean 2.ocean continent 3.continent
  continent

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OCEAN OCEAN CONVERGENT BOUNDARY Subduction
Zone Mantle rock melts magma rises to the
surface, creating islands.
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OCEAN CONTINENT CONVERGENT BOUNDARY Subduction
ZoneOceanic Crust is more dense sinks under
Continental Crust
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CONTINENT CONTINENT CONVERGENT BOUNDARY
Plates collide the edges crumple, causing
uplift mountains
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TRANSFORM BOUNDARY

• TRANSFORM When two plates are moving past each
  other.
• Characteristics San Andreas Boundary

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Ex SAN ANDREAS BOUNDARY
The Pacific plate and North American plate grind
past each other side by side.
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REVIEW
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HOT SPOTS
AREA WITHIN A PLATE WHERE MAGMA WORKS ITSELF TO
THE SURFACE ARE CALLED HOT SPOTS. HOT SPOTS ARE
STATIONARY SO WHEN THE PLATE ABOVE IT MOVES A NEW
VOLCANOE FORMS.
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