PLATE TECTONICS
Why the Earth is Like It Is
What Did
The Earth
Look Like
In The
Past?
Why Do Plates Move?
Plates are “pushed”
and “pulled” over the
surface of the Earth
due to unbalanced
forces.
REMEMBER
CONVECTION?
Convection currents
reach the surface,
plates are pushed
apart.
As the plates move
away from each
other, part of them
are pulled into the
Earth’s mantle.
Names of Plates
Plate Move In Different Ways
Plates Move Away From Each Other
This is called Divergence – these are constructive boundaries
since they produce new land as magma rises to the surface to fill
in the space.
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Resulting landforms from
Divergence – Moving Apart
Rift Valley
forms if the
land is above
water
Sea Floor
Spreading forms
ridges as the sea
floor spreads
apart and lava
rises
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Plates Move Toward Each Other
This is called Convergence – these are destructive boundaries
since they deform the plates. Collision or Subduction occurs as
the more dense plate slide under the less dense plate.
Continent/Continent
Ocean/Continent
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Ocean/Ocean
Resulting landforms from
Convergence – Moving Together
Trenches
Mountains
Structural
Mountains
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Volcanoes
Plates slide paste each other
When plates are sliding past each other in opposite
directions it is a Transform Boundary.
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•
Transform boundaries occur in a few places to accommodate
lateral, or side to side motion, in which plates slide past one
another.
Resulting landforms from
Transform Boundaries – sliding past each other
When two plates are
sliding past each other in
opposite directions it
creates a fault line. The
result of two huge plates of
land moving opposite one
another is that massive
amounts of energy build
up. Occasionally this
energy is released
suddenly in the form of an
earthquake.
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TAKS Type Items
and Answer Analysis
As two continental plates move toward
each other, what landforms would you
expect to see?
Volcanoes
B. Cliffs
C. Mesas
D. Structural Mountains
A.
As two continental plates move toward
each other, what landforms would you
expect to see?
Volcanoes
Incorrect
These form at edges of plates or over
hot spots.
A.
As two continental plates move toward
each other, what landforms would you
expect to see?
Cliffs
Incorrect
These are erosional landforms or minor
uplift areas.
B.
As two continental plates move toward
each other, what landforms would you
expect to see?
Mesas
Incorrect
These are erosional landforms in a
desert.
C.
As two continental plates move toward
each other, what landforms would you
expect to see?
D.
Structural
Mountains –
correct Two continental
masses will push
into each other
and “crumple” the
edges to form
mountains.
Where would you find the newest
land on Earth?
A.
B.
C.
D.
In areas of continental convergence
In areas where two ocean plates come
together
In areas where plates are moving apart
In areas where two plates are sliding past each
other
Where would you find the newest
land on Earth?
In areas of continental convergence
Incorrect
Structural mountains would form here from
existing land.
A.
Where would you find the newest
land on Earth?
In areas where two ocean plates come
together
Incorrect
You would find trenches and subduction in this
area.
B.
Where would you find the newest
land on Earth?
In areas where two plates are sliding past each
other
Incorrect
You would find land movement, but not new
land being formed.
D.
Where would you find the newest
land on Earth?
In areas where plates are moving apart
Correct
When plates move apart, it is due to magma
reaching the surface. When magma cools, new
land is formed.
C.