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Geography Y10
Revision Session
Paper 1
Dynamic Planet
This unit has 3 sections; A, B and C:
• Section A: Introduction to the Dynamic Planet
Topics: Restless Earth, Climate and Change, Battle for the Biosphere
and Water World.
• Section B: Small-scale Dynamic Planet
Topic: River Processes and Pressures
• Section C: Large-scale Dynamic Planet
Topic: Extreme Climates
Assessment
1 hour written exam, A=32 marks (8 per topic), B=9 marks,
C=9 marks
What do we need to revise for
the Y10 exam?
• For your Geography exam, it is important that
you revise all work covered so far this year:
1. Restless Earth
2. Climate and Change
3. Battle for the Biosphere
4. Water World
5. River Processes and Pressures
6. Extreme Climates
Unit 1:
Restless
Earth
Why do the plates move?
Crust
Convention
Currents
Mantle
Convection Currents
• The Earth’s Tectonic Plates all move very slowly
on the mantle.
• The plates move due to convection currents in
the mantle.
• These are hot currents of molten rock that
slowly move within the mantle and cause the
plates above them to move, usually by as little as
one or two centimetres each year.
• Earthquakes and volcanoes mainly happen at plate
boundaries, where plates meet.
Why Do The Plates Move?
• The convection currents in the mantle
are themselves driven by the heat of
the core. That heat is partly created
by the pressure of overlying material
but also by the radioactivity of the
core material itself. As long as there
is a temperature difference with
depth there will be a cycle of rising
and sinking material.
(A lava lamp)
The Crust
• The crust is made up of sections, called
plates.
• There are two types of crust:
Continental Crust
Oceanic Crust
It forms land
Under the ocean
Mostly made of granite,
which is low density.
Mostly igneous rock, which
is much denser.
It is usually 30 – 50km thick Much thinner, 6-8km thick.
Eurasian
North
American
Pacific
African Plate
Nazca
South
American
Indo Australian
Plate
Antarctic
Tectonic Plate
Names
Plate Boundaries
• Where two plates meet is called a plate
boundary / plate margin.
• There are four types of plate
boundaries:
1.
2.
3.
4.
Conservative margins
Destructive margins
Collision margins
Constructive margins
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.
A destructive plate boundary is found
where a continental plate meets an
oceanic plate.
Destructive
Plate
Boundary
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.
Collision
Boundary
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.
Conservative plate boundaries
exist where two plates do not
directly collide but slide past
each other along a fault
(weakness).
Conservative
Boundary
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.