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Transcript
Tectonics
The changing position of
the continents is called
continental drift.
Plates move a few
centimetres a year.
Plate movement causes
continents to collide, and
split apart.
The Earth’s crust is divided
up into 7 large and 13 small
plates.
They float on the molten
mantle.
The plate boundaries are
under extreme pressure
and this is where most of
the Earth’s earthquakes
and volcanoes occur.
Convection currents in the
mantle cause the plates to
move.
Put the sentences in the correct
order. They describe the process of
PLATE TECTONICS.
Tectonics
The Earth’s crust is divided up into 7 large and
13 small plates.
Plates move a few centimetres a year.
They float on the molten mantle.
Convection currents in the mantle cause the
plates to move.
Plate movement causes continents to collide,
and split apart.
The changing position of the continents is
called continental drift.
The plate boundaries are under extreme
pressure and this is where most of the Earth’s
earthquakes and volcanoes occur.
Tectonics
Plate Boundaries
Tectonics
Plate Boundaries
Tectonics
Plate Boundaries
North
American
Eurasian
Pacific
Pacific
African
Nazca
South
American
Indo-Australian
Plate
Antarctic
Tectonics
Plate Boundaries
Tectonics Types of Boundary
Types of Plates
Continental crust is much thicker than Oceanic crust. As a result it has more
force and can ‘push the Oceanic crust around’.
Tectonics Types of Boundary
Divergent Plate Boundaries
At a divergent plate boundary, two plates move apart.
As the two plates move apart, magma rises up to fill the gap. This causes
volcanoes.
However, since the magma can escape easily at the surface the volcano does not
erupt with much force.
Earthquakes are also found at divergent boundaries.
An example of a constructive boundary is the Mid-Atlantic Ridge.
Tectonics Types of Boundary
Divergent Plate Boundaries
Tectonics Types of Boundary
Divergent Plate Boundaries
mid-ocean ridge
ocean
mantle
Tectonics Types of Boundary
Convergent Plate Boundaries
A convergent plate boundary is found where a continental plate meets an
oceanic plate.
The oceanic plate descends under the continental plate because it is denser. As
the plate descends it starts to melt due to the friction caused by the movement
between the plates.
This melted plate is now hot, liquid rock (magma). The magma rises through the
gaps in the continental plate.
If it reaches the surface, the liquid rock forms a volcano.
Tectonics Types of Boundary
Convergent Plate Boundaries
Tectonics Types of Boundary
Convergent Plate Boundaries
F
E
A
B
D
1.oceanic plate
C
2. The oceanic crust sinks under
the less dense continental crust.
4. continental crust
5. explosive volcanoes
3. The oceanic crust
melts and rises.
6. mantle
Tectonics Types of Boundary
Convergent Plate Boundaries
Tectonics Types of Boundary
Convergent Plate Boundaries
Collision boundaries occur when two plates of similar densities move together
(i.e. a continental plate and a continental plate).
This causes the material between them to buckle and rise up, forming fold
mountains.
The Himalayas are an example of a chain of fold mountains.
They have been formed by the African plate colliding into the Eurasian plate.
Tectonics Types of Boundary
Convergent Plate Boundaries
Tectonics Types of Boundary
Conservative Plate Boundaries
Conservative plate boundaries exist where two plates do not directly collide but
slide past each other along a fault (weakness).
No volcanoes are found along these plate boundaries, but earthquakes do occur.
An example of such a boundary is the San Andreas Fault in California.
Tectonics Types of Boundary
Conservative Plate Boundaries
Tectonics
Where are what type of boundary?
North
American
Eurasian
Pacific
Pacific
African
Nazca
South
American
Indo-Australian
Plate
Antarctic