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Plate Tectonics
PROOF or it didn’t happen…
EVIDENCE #3
Most features on land and in the ocean are the result of
geological activity and earthquakes along plate
boundaries (where the pieces meet).
• The exact patterns depend on HOW the plates are
moving… together – apart – or sliding.
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Changes in Landform areas over Geologic Time
Summary
As the plates continued to __move__ and split___
apart, oceans___ were formed, landmasses____
collided and split apart until the Earth’s
landmasses came to be in the positions they are
now;
Evidence of these landmass collisions and splits
comes from fossils, landform shape, features, and
rock structures, and climate change.
Landmass changes can occur at hot spots within
______Lithospheric____ plates;
Earth’s landmasses_ will continue to move and
change during the geologic time of the future.
What else do we know?
The plates are still moving!!
Though they move VERY SLOWLY 
between 1-10 centimeters per year
What else do we know?
There are places within the lithosphere where
magma rises and leaks through the crust
This is called a HOT SPOT and is where volcanic
activity occurs.
HOTSPOTS are how the Hawaiian islands were
formed!!
REVIEW CHECK
Where are the Tectonic plates located?
What part of the Earth do they float on?
How do they move?
Plate Boundaries
Plates float on the upper mantle (Asthenosphere)
They move due to Convection Currents
The edges of the different plates meet at lines called
Boundaries
At the border of plate boundaries are….
FAULTS—breaks or cracks in the
Earth’s crust
Types of Boundaries
There are 3 different types of
boundaries that occur because of their
different movement
 Convergent Boundaries
 Divergent Boundaries
 Transform Boundaries
Convergent Boundaries
 WHAT IS A CONVERGENT BOUNDARY?
WHEN ______2__________ PLATES COME
TOGETHER AND ____COLLIDE__________.
 KEY WORD: ______COLLIDE______
 ILLUSTRATION BELOW
CRUST
CRUST
What happens when they hit?
• The DENSITY of the crustal plates
colliding determines if either…
A) One plate goes under the other
B) The plates rise up
Either way…. An Earthquake can always (and
often does) occur when two plates interact
Collisions
PREDICTION TIME: Basalt (what
Oceanic Crust is made out of) is
more dense than Continental Crust.
What do you think will happen
to the plate that is MORE
dense?
• THE ACTIVITY DEPENDS UPON THE TYPES OF
___CRUST_______.
• More dense _OCEANIC_____ plate slides
under less dense _CONTINENTAL_____ plate
or another _____OCEANIC___ plate which is
called the __SUBDUCTION ZONE___.
SUBDUCTION ZONE
• Subduction is a way of recycling the
oceanic crust. Eventually the
subducting slab sinks down into the
mantle to be recycled. It is for this
reason that the oceanic crust is
much younger than the continental
crust which is not recycled.
COVERGENT BOUNDARY COLLISIONS
• THERE ARE ____3______ TYPES OF
COLLISIONS FOR THE CONVERGENT
BOUNDARY.
CONTINENTAL-OCEANIC COLLISION
(CO)
• FORMS WHEN CONTINENTAL AND OCEANIC
PLATE COLLIDES CREATING A
___SUBDUCTION ZONE____ AS THE OCEANIC
(MORE DENSE & THINNER CRUST) SUBDUCTS
OR SINKS BELOW THE CONTINENTAL CRUST.
SUBDUCTION ZONE
CRUST INVOLVED: OCEANIC & CONTINENTAL
MOVEMENT: More dense plate (Oceanic) slides
under or sinks below the less dense Continental
plate.
FORCE/STRESS ON THE ROCK: Compression
(push or squeeze rocks)
FAULT: REVERSE
LAND FORMS:
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SUBDUCTION ZONES
Smaller Mountain Ranges (Andes)
Volcanic Activity
Trench
Earthquakes
SUBDUCTION ZONE
SUBDUCTION ZONE
TRENCHES
ISLAND ARC
VOLCANIC ARC
OCEANIC-OCEANIC COLLISION (OO)
• FORMS WHEN 2 OCEANIC PLATES COLLIDE
CREATING A _____SUBDUCTION ZONE_____
AS THE MORE DENSE OCEANIC CRUST
SUBDUCTS OR SINKS BELOW LESS DENSE
OCEANIC CRUST.
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NAME OF THE STRESS/FORCE: COMPRESSION
NAME OF THE FAULT: REVERSE
WHAT CAN FORM FROM THIS COLLISION?
SUBDUCTION ZONE & VOLCANIC ACTIVITY
– Deep Trenches, crust going below into the mantle melts
and recycles
– Island arcs (volcanic islands)
– volcano arcs/chains
– Earthquakes
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CONTINENTAL-CONTINENTAL
COLLISION (CC)
• FORMS WHEN 2 CONTINENTAL PLATES
COLLIDE AND BUCKLING UP TO CREATE A
MOUNTAINS and MOUNTAIN RANGES
(Himalayas.
DIVERGENT BOUNDARY
• WHAT IS A DIVERGENT BOUNDARY? WHEN
__2___ PLATES SPREAD OR MOVE
___APART________/DIVIDE. KEY WORD:
___DIVIDE_______
• ILLUSTRATION:
Divergent Boundaries
 The place where two
plates move apart—or
diverge—is called a
divergent boundary
 Most divergent
boundaries occur at the
mid-ocean ridge—so
crust is forming
 When divergent
boundaries occur on land,
a rift valley is formed
RIDGES
• RIDGES- WHEN PLATES DIVIDE UNDER WATER
(MID-OCEAN RIDGES-CAUSED BY VOLCANIC
ACTIVITY)
RIFTS
• RIFTS- WHEN 2 PLATES DIVIDE ON LAND
DIVERGENT
• NAME OF THE STRESS/FORCE: TENSION
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• NAME OF THE FAULT: NORMAL
•
• WHAT CAN FORM FROM THIS BOUNDARY?
•
RIFTS, RIDGES, VOLCANIC ACTIVITY, & NEW
CRUST
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• ACRONYM: D-TOWN NATION (DIVERGENTTENSION- NORMAL)
TRANSFORM BOUNDARY
• WHAT IS A TRANSFORM BOUNDARY? WHEN
___2___ PLATES ___SLIDE___ PASS EACH
OTHER. KEY WORD: _____SLIDE_____
Transform Boundaries
 Along transform
boundaries crust isn’t
created or destroyed
 At a transform
boundary the two
plates slip past each
other
TRANSFORM BOUNDARY
• NAME OF THE STRESS/FORCE: SHEARING
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• NAME OF THE FAULT: STRIKE SLIP
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• WHAT CAN FORM FROM THIS BOUNDARY?
•
EARTHQUAKES, FAULTS, & VOLCANIC
ACTIVITY
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• ACRONYM: TASTE SOME SKITTLES
(TRANSFORM-SHEARING-STRIKE SLIP)
Station Work
1. WHAT IS THE THEORY OF PLATE TECTONICS?
2. WHAT IS A RIFT VALLEY? HOW IS IT FORMED?
3. WHAT TYPES OF PLATE MOVEMENT OCCUR AT
PLATE BOUNDARIES
4. WHAT MAJOR EVENT BEGAN ABOUT 225 MILLION
YEARS AGO?
5. LABEL ALL THE BOUNDARIES ON FIGURE 5
(OVERHEAD) AS TRANSFORM, CONVERGENT OR
DIVERGENT.