Download Plate Tectonics

Plate Tectonics What do these things have in common? What could those things possibly have to do with boiling pasta?? Convec:on currents Plate Movement
•  “Plates” of lithosphere are moved around by the
underlying hot mantle convection cells
Convec:on Currents •  Hot magma in the Earth moves
toward the surface, cools, then
sinks again.
•  Creates convection currents
beneath the plates that cause
the plates to move.
Three types of plate boundary
•  Divergent
•  Convergent
•  Transform
Divergent Boundaries
•  Spreading ridges
–  As plates move apart new material is erupted to
fill the gap
Oceanic/Oceanic Divergent
ß à
•  Sea floor spreading –
ocean grows
•  Forms Mid-Ocean
Ridges
•  Example –
•  Mid Atlantic Ridge
•  Forms a trench in the
middle
Age of Oceanic Crust Mid-Atlantic Ridge
Red –
youngest
crust
Blue –
oldest
crust
Gray- land
Courtesy of www.ngdc.noaa.gov
Continental/Continental Divergent
ß à
•  Africa’s Great Rift
Valley
•  Can you tell where
the continent is
separating?
Iceland: An example of continental rifting
•  Iceland has a divergent
plate boundary running
through its middle
Convergent Boundaries
•  There are three types of convergent
plate boundaries
–  Continental-oceanic crust collision
–  Oceanic-oceanic crust collision
–  Continental-continental crust collision
Continent-Oceanic Crust Collision
•  Called SUBDUCTION
Subduction
•  Oceanic lithosphere subducts
underneath the continental
lithosphere
•  Oceanic lithosphere heats and
melts into the magma as it
sinks
•  The pressure causes magma
to press up through the
boundary, creating volcanic
mountains
•  E.g. The Andes Mountains
The Andes Mountains
•  The longest
mountain range in
the world.
•  In 7 countries in
South America Venezuela,
Colombia,
Ecuador, Peru,
Bolivia, Chile, &
Argentina.
Oceanic-Oceanic Plate Collision
•  When two oceanic plates collide, one runs over the other
which causes it to sink into the mantle forming a
subduction zone.
•  The subducting plate is bent downward to form a very
deep depression in the ocean floor called a trench.
•  The worlds deepest parts of the ocean are found along
trenches.
Oceanic-Oceanic Plate Collision
•  The pressure causes
volcanoes to rise up.
When these
volcanoes stick out of
the water, they form
what is called an
island arc, or a string
of volcanic islands
Aleutian
Islands
Alaska, USA
Continental-Continental Collision
•  Forms folded mountains,
•  e.g. Himalaya Mountains
Himalayas
Transform Boundaries
• 
• 
Where plates slide past each
other (horizontally)
The friction causes earthquakes
Above: View of
the San
Andreas
transform
fault,
California
Plate Tectonics Summary
•  The Earth is made up of 3 main layers (core,
mantle, crust).
•  On the surface of the Earth are tectonic
plates that slowly move around the globe
•  Plates are made of crust and upper mantle
(lithosphere) and float on the asthenosphere
•  There are 2 types of plates
•  There are 3 types of plate boundaries
•  Volcanoes and Earthquakes are closely
linked to the margins of the tectonic plates
Who figures all this out?