What is plate tectonics?
The build up of plates…?
Or is it the build up of food onto a plate…?
Plate: Large, rigid slab of Earth’s solid rock
+ Tectonics: From the Greek root “to build”
Plate Tectonics =
The term which refers
to how the Earth’s
surface is built of
-Plates: large, rigid slab of Earth’s solid rock
- are broken pieces from the lithosphere layer which is the crust of the Earth
- ride on the hotter and weaker layer of the upper portion of the mantle called the
- due to the various pressure in the upper mantle, the layer is plastic which allows the
plates of the lithosphere to move around
--> Theory of Plate Tectonics: Movements of the Earth’s plates
Earth’s Major Plates
Transform Fault (Sliding)
-two plates grind past each other without
the production or destruction of lithosphere
-San Andreas Fault in California.
-> Pacific plate is moving toward the
northwest grinding past the North American
plate which is traveling in the opposite
- Earthquakes are triggered along the fault
Divergent (Constructive) -Plates move away from each other.
Oceanic plate & Oceanic plate -When two plates diverge, factures occur
which are immediately filled with molten rock
that wells up from the asthenosphere. This
hot material cools and creates a new seafloor.
-As a result, new oceanic crust (lithosphere)
is continuously being created between the
-The older crust moves away from the
boundary, as it does so, it cools and contracts
hence increasing in density and in thickness.
-This is why the older and cooler oceanic
crusts are deeper.
Continental plate & Continental plate
-Two continental plates
moves apart from each
-The East African rift
valleys represent the
initial stage in the
breakup of a continent.
-Volcanic mountains such
as Kilimanjaro and
Mount Kenya are
examples of the rift
valleys that were formed
by the associated faulting
taking place. http://taos-telecommunity.org/EPOW/EPOW-
-Plates move towards each other,
resulting in subduction (consumption)
of oceanic lithosphere into the mantle.
-When two plates converge, the
leading edge of one is bent
downward, allowing it to descend
beneath the other.
-This region is called a subduction
-There are three types of convergent
Convergent -When a continental plate collides with an
Oceanic plate & Continental plate oceanic plate, the less dense continental plate
will continue on its course while the denser
oceanic plate will sink under the continental plate
and into the asthenosphere.
-As the descending plate increases in depth, the
heat generated causes partial melting of the
mantle creating magma which will accumulate
beneath the overlying continental crust.
-This can result in explosive volcanoes
-Example is the Andes in South America
Ushuaia Bay with the
southernmost tip of
Andes in the
Oceanic plate & Oceanic plate -Two oceanic plate convergence, one will
descend beneath the other.
-Triggers volcanic activity …just like the
oceanic-continental convergence, but the
volcanoes forms on the ocean floor.
-If the activity continues the volcanoes will
emerge as islands in the ocean
- Examples are the Mariana Islands in the
western Pacific Ocean and the Tonga
http://stloe.most.go.th/html/lo_index/LOcanada4/403/images/3_3.jpg is one of the
Convergent -When two plates carrying continental
Continental plate & continental plate
crust converge it causes collision.
-Since both plates are of low density and
buoyant by the nature of the continental
rock, neither will subduct.
-Folding and deforming of sediments
along the continental margins are then
-Example is the Himalayas which are a
result of the Australian-Indian plate
ramming into the Eurasian plate.
Now you can EAT your snacks!