Transcript Plate Tectonics

Plate Tectonics
Plate Tectonics
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A quilt of plates
carrying continents
and oceans that slide
over magma causing
changes in features of
the earth’s surface
Theory of Continental
Drift
Proven in 1967 –
1968 by scientists
Based on a theory by
Alfred Wagener
Continental Drift
• Alfred Wagener
proposed the theory
in the 1920’s
• Based on matching
fossils in different
world locations
• Believed that
everything started
from a super
continent named
Pangaea
Types of Plate Movement
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Sea-floor spreading
Action – magma surfaces from a
crack in the plates causing them
to push apart
Results – causes some
volcanic/earthquake activity and a
scar-like ridge along the surface of
the ocean floor.
Example – Mid-Atlantic Ridge
Subduction
Action – one plate dives under
another plate
Results – Earthquakes and
volcanic activity
Example – Pacific Plate under the
Asian Plate, the Ring of Fire
Colliding and Grinding Plates
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Collision (convergent)
Action – one plate crashes into
another plate and then continues
pushing into it.
Results – Formation of mountains,
earthquakes
Example – Indian Sub-continent
into the Asian Plate. Himalaya
Mountains
Grinding
Action – two plates slipping/sliding
along an outer edge
Results – earthquakes, folding and
faulting, some volcanic activity
Example – Pacific and North
American Plates. California,
Washington, and Oregon
earthquake activity
Explanation
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These types of actions along with Hot Spots
(Hawaii) change the surface of the earth from
internal forces