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The Dynamic Earth:
PLATE TECTONICS
Types of Plate Boundaries
EQ:
How does plate
tectonics shape
the earth’s
surface?
Types of Plate Boundaries
There are approximately 20 plates
found on the Earth’s crust.
These plates are moving in relation
to one another in a process known
as PLATE TECTONICS.
Review
What is the
What are the 2
lithosphere?
types of crust?
Convergent Boundaries
A convergent
boundary is a
boundary
between two
lithosphere
plates that are
moving toward
each other, or
converging.
Convergent Boundaries
Earth has 2 types of crust on it’s surface;
Continental and Oceanic Crust.
There are 3 different types of convergent
boundaries and processes involved
depending on the types of crust involved.
These processes are known as either
Subduction or Collison.
Convergent: Ocean to Ocean
2 oceanic plate colliding!
 Volcanic Island
Arcs are a feature
formed at these
boundaries.
 Current
Example: the
islands of Hawaii
Convergent: Continent to Continent
2 Continental plates are colliding!
If two plates
each carrying
continents
collide, they
become welded
into a single,
larger continent.
Convergent: Continent to Continent
Feature: The collision causes the
crust at the boundary to be pushed
upward into a mountain range.
Current
Example: The
world’s
tallest
mountains
are known as
the
Himalayas.
Convergent: Continent to Ocean
1 Oceanic plate and 1 Continental plate collide.
When an oceanic
plate collides
with a
continental plate,
the oceanic plate
sinks under the
continental plate.
This is because the oceanic plate is
made of basalt which is more dense
than the granite composed
continental crust.
Convergent: Ocean to Continent
When a continental
plate and an oceanic
plate collide
common features
include:
volcanoes along the
coast line
deep-sea trenches
Convergent: Ocean to Continent
Current Examples of volcanoes:
Mt. St. Helens, Mount Katmai,
Mount Pinatubo, Montserrat,
Mount Pelee
Divergent Boundaries
 A divergent boundary
is a boundary between
two lithosphere plates
that are moving apart.
 They are sometimes
called spreading
centers.
Divergent Boundaries: Mid Ocean Ridges
In a process called sea floor
spreading, molten rock forces its
way upward through cracks, or
rifts. The molten rock hardens
into new oceanic crust.
Divergent Boundaries
Hydrothermal vents
and the mid-ocean
ridge are found at
divergent
boundaries.
Divergent Boundaries
 Examples:
 Mid-
The Great Rift Valley in
East Africa
Atlantic
Ridge
 Great
Rift
Valley
Transform Boundaries
Transform Boundaries
 A transform boundary is a
boundary between two
plates that are sliding past
one another.
 Current Example: San
Andreas Fault- moving
about 5 cm/year.
Transform Boundaries
The main feature of
transform
boundaries are…
EARTHQUAKES
Observe animations of processes that occur along plate boundaries.
Plate Tectonics Map - Plate Boundary Map