1. The Earth is like an Apple!
CRUST
(where we live)
MANTLE
CORE
The Structure of the Earth
CRUST
MANTLE
CORE
•Inner
•Outer
2.
3.
4. The 2 different types ofThe 2 different types of
plateplate
CONTINENTAL OCEANIC
- 25-100km thick
- Light (and so does not sink)
- Not destroyed as easily as oceanic
crust
- 5-10KM thick
- Dense
- Constantly being renewed and
destroyed
5. Convection
Currents
Mantle
Crust
Plates move due to convectionPlates move due to convection
currentscurrents
The hot magma rises from above the coreThe hot magma rises from above the core
As it cools, it sinks and then moves downwardsAs it cools, it sinks and then moves downwards
towards the core again.towards the core again.
This causes the plates to move apartThis causes the plates to move apart
9. Evidence for plate tectonics
1. Study of fossils – similar fossils are found on different
continents. This is evidence that these regions were once
very close or joined together.
3. Shape of continents fit together like a jigsaw.
Africa
South
America
2. Pattern of rocks – similar pattern of rock layers on
different continents is evidence that the rocks were
once close together or joined.
10. What are plate margins?What are plate margins?
This is where 2 or more plates meet.This is where 2 or more plates meet.
There are 3 different types of plateThere are 3 different types of plate
movement;movement;
Away from each other (Constructive – asAway from each other (Constructive – as
new crust is constructed)new crust is constructed)
Towards each other (Destructive – as crustTowards each other (Destructive – as crust
is being destroyed). This category can beis being destroyed). This category can be
sub divided into subduction and destructivesub divided into subduction and destructive
Sliding past each other (Conservative)Sliding past each other (Conservative)
11. A destructive 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.
1) Destructive Plate Boundary
a) Subduction
12. Collision boundaries occur when 2
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.
1) Destructive cont.
b) Collision Boundary
13. 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.
2) Conservative Boundary
14. 3) Constructive Plate Boundary
At a constructive plate boundary,
two plates move apart. As the two
plates move apart, magma rises up
to fill the gap. This causes
volcanoes at this type of boundary.
However, since the magma can
escape easily at the surface the
volcano does not erupt with much
force. Earthquakes are also found
at constructive boundaries.
An example of a constructive
boundary is the Mid-Atlantic Ridge.
15. Sea Floor
Spreading!
Did you know that
the ocean floor in
the Atlantic is
growing by 3cm per
year?
Which of the following pairs of continents are
moving further away from each other?
1) Europe and Africa
2) Europe and North America
3) South America and North America
Mid-Atlantic ridge
16. Name this plate
boundary
Continental
crust
Mantl
e
The oceanic
crust melts and
rises
Explosive volcanoes
Oceanic plate
The oceanic crust sinks under
the less dense continental
crust
Earthquakes occur due to friction
Match the labels to the letters
A B
C D
E
F
G
