Year 10 exams: tectonics revision
Bingo!
Ways to revise
Is this map clearer or not? Why?
This map shows the plate boundaries again, and it also shows where we
find volcanoes. These are shown by red dots.
Is there a pattern that you can describe?
All the dots and circles on this map show earthquakes. What do you
think the bigger circles show?
Can you see any links between this map and the last one?
Now make sure that you answer the key questions:
1.
2.
3.
Do earthquakes and volcanoes appear all over the earth’s surface
or only in certain places?
Is there a recognisable pattern to where earthquakes seem to occur?
Which areas of the earth seem to be at the highest risk from
earthquakes?
We can take our understanding a little further. For example:
Moves in a different way
to this one
This plate boundary
How…..?
Now write down:
1.
2.
How the plates move.
What happens when they move.
This is called a constructive plate
boundary
At this plate boundary, the plates move
apart very slowly. This causes earthquakes.
As they move, magma rises up, and if it
reaches the surface it will form a
volcano.
This is called a destructive plate
boundary
At this plate boundary, the plates move
together very slowly. As they rub
together this causes a lot of friction.
Friction leads to earthquakes, and can
also cause volcanoes because of the heat.
3 Types of Plate Margin
• Constructive
(Divergent)
Tensional
• Destructive
(Convergent)
Compressional
• Conservative
(Transform)
Passive
From memory:
• Sketch and label a diagram of destructive
(convergent) and constructive (divergent)
plate bounday
Constructive plate margin
At the plate margins, new crust
is being formed and old crust
destroyed. Along the Mid
Atlantic Ridge, the plates are
being pulled apart and molten
rock, or magma, rises up from
the mantle and sets hard on the
ocean floor. In some places this
occurs on land, as in Iceland
which sits on the Mid
Atlantic Ridge.
Destructive plate margin
The Mid Atlantic Ridge is a
constructive plate margin.
Most volcanoes occur at
destructive plate margins.
Here, the old crust is forced
back down into the mantle in
the subduction zone. Massive
friction causes melting. This
molten rock forces its way to
the surface to
form volcanoes.
Conservative plate margin
Part of the
San
Andreas
Fault
Where crust is neither produced nor destroyed as the plates
slide horizontally past each other.
Hotspots
Sometimes volcanoes (volcanic arcs)
form at hotspots as well as at
constructive and destructive
margins. At a hot spot, the
convection currents are very strong
and heat becomes localised under
the crust in the centre of a plate.
The Hawaiian islands are an
example, forming in the middle of
the Pacific plate.
Sample exam questions related to
plate tectonics
1. Some plate boundaries are known as constructive.
Explain the processes that take place at constructive
plate boundaries. (4)
2. Landform C shown on Figure 4a is an area of fold
mountains. Explain how they are formed. You may
use a diagram to help your answer. (4)
3. Explain how volcanoes form over hotspots. Use an
annotated diagram or diagrams in your answer. (4)
Case studies: Montserrat and San
Francisco-List 5 key facts you need to
remember
Montserrat
San Francisco
Examples of exam questions
• Choose a volcanic eruption or an earthquake you
have studied.
Explain the effects of the volcanic eruption or the
earthquake on the people and the environment.
(6)
• Choose a volcanic eruption or an earthquake you
have studied.
Explain the cause of the volcanic eruption or the
earthquake. (6)