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PLATE%20TECTONICS

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Title: PLATE TECTONICS Author: A satisfied Microsoft Office User Last modified by: CUSD95 Created Date: 5/14/2002 10:04:27 PM Document presentation format – PowerPoint PPT presentation

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Title: PLATE%20TECTONICS


1
PLATE TECTONICS
2
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.

3
LITHOSPHERE / ASTHENSPHERE
4
CONVECTION CURRENTS-Hot magma from the mantle
rises, cools, sinks.-Mantle moves drags
plates along with it.
5
PLATES
6
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7
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).

8
DIVERGENTEx Seafloor Spreading
9
CONVERGENT
  • CONVERGENT When two plates collide.
  • Characteristics Mountains, most earthquakes,
    Volcanoes, and trenches
  • 1.ocean ocean 2.ocean continent 3.continent
    continent

10
OCEAN OCEAN CONVERGENT BOUNDARY Subduction
Zone Mantle rock melts magma rises to the
surface, creating islands.
11
OCEAN CONTINENT CONVERGENT BOUNDARY Subduction
ZoneOceanic Crust is more dense sinks under
Continental Crust
12
CONTINENT CONTINENT CONVERGENT BOUNDARY
Plates collide the edges crumple, causing
uplift mountains
13
TRANSFORM BOUNDARY
  • TRANSFORM When two plates are moving past each
    other.
  • Characteristics San Andreas Boundary

14
Ex SAN ANDREAS BOUNDARY
The Pacific plate and North American plate grind
past each other side by side.
15
REVIEW
16
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.
17
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18
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