Download Plate Boundaries

The
Big
Crack
Up!
LEARNING TARGET 4:
Describe plate movements that
cause ocean basins, ocean
trenches, and mountains to form;
Explain the causes of
earthquakes and volcanic
eruptions.
EARTH: A GIGANTIC RECYCLING CENTER!
Plate Tectonics
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The theory of plate tectonics is based on
the evaluation of scientific evidence and
observation- The Scientific Method
Continental Drift hypothesis
Seafloor Spreading hypothesis
Plate Boundaries
Convergent
Divergent
Transform
Plate Tectonics

Explains the configuration of topographic
features of the Earth- mountains, valleys,
volcanoes, islands, oceanic trenches, faults
Tectonic plates
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Are composed of the lithosphere
Move as a coherent mass
May contain oceanic crust and continental
crust
Plate Boundaries
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Where does
the energy
come from to
move plates?
Where does
it go?
Topographic features on the Earth’s surface
reflects what is happening in the mantle.
Convergent Plate Boundary
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Volcanic arc
Oceanic crust subducts under continental
crust
Melting occurs at about 100 miles down
Hot more buoyant material rises
Volcanic Arc
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Oceanic and
continental crust
Cascade Range, Andes,
Alaska
Characteristics: large
volcanoes; subduction
zone; trench; oceanic
crust subducts under
continental crust
Convergent
Plate Boundary
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Map and crosssection views of the
subduction zone
The oceanic Juan de
Fuca plate subducts
under the
continental North
American Plate
Convergent Plate Boundary
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Two oceanic crusts
Oceanic crust subducts under
opposing oceanic crust
Oldest oceanic crust subducts
Island Arc
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Japan, Indonesia, Philippines, Caribbean,
Aleutian Islands
Convergent Plate Boundary
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Earthquakes trace the
SUBDUCTING SLAB to
about 500 miles or
650 kilometers
Gold dots represent earthquake hypocenters
Sketch a cross-section of a
convergent plate boundary that
contains an oceanic crust.
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Label with the following terms:
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Subduction zone
Trench
Area of melting
Area of volcanism
Arrows indicating direction of plate movement
Convergent Plate Boundaries
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Two continental crusts
Neither subduct due to buoyancy of crusts
Mountains form
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India collided
with Asia about
40 million years
ago
Mt. Everest,
29,000 feet
Divergent Plate Boundary
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Two plates move apart
Run through ocean basins
Divergent Plate Boundaries
New crust forms at mid-oceanic ridges. The seafloor
spreads out. This is Seafloor Spreading.
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In most locations, midocean ridges are 6,500
feet (1,980 m) or more
below the surface of
the oceans.
In a few places, they reach
above sea level and form
islands. Iceland (North
Atlantic), the Azores (west
of Portugal), and Tristan de
Cunha (south Atlantic
between southern Africa
and South America)
How Does Seafloor Spreading Affect
Neighboring Plates?
East Africa Rift Zone

Continental
crust is
beginning to
pull-apart
forming a rift
valley
Process of Ocean Basin Formation
Sketch a cross section of a
divergent plate boundary.
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Label with the following terms:
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rift valley;
oceanic ridge;
oceanic crust;
. volcanism;
location of melting and
and arrows indicating direction of plate
movement
Transform Plate Boundary
Transform Plate Boundary
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The tectonic plates
pass by each other
Connected to other
plate boundaries
San Andreas Fault
Label the plates,
their movement
directions, and the
San Andreas Fault
Hot Spots
Animation of
Formation
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Stationary plumes of hot material that
initiate at the core/mantle interface
Hawaii: the plume is beneath oceanic crust
Hot Spots
Hot Spots
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Yellowstone is associated with a hot spot
under continental crust
Name the landform associated
with oceanic crust subducting
under continental crust.
Oceanic crust?