Transcript Year 4-Tectonic Landscapes Exam Skills 1

TECTONIC LANDSCAPES
Memory challenge 1
A- How to describe distributions of earthquakes and
volcanoes
1- recognise the overall distribution
2- describe the distribution in more detail. Use
oceans/continents in your description.
3- is there any exception to the distribution described at 1
and 2?
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Example 1: Map without plate boundaries
Volcanoes and earthquakes occur in narrow belts
(overall distribution). The largest belt runs around the
Pacific Ocean, along the edge of continents.
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Other bands are found in the middle of oceans
such as the belt that extends down the entire
length of the mid-Atlantic Ocean.
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Another major belt travels through the
continents of Europe and Asia and Eastern
Africa.
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Map of the distribution of
volcanoes with plate boundaries
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1- Volcanoes occur in narrow
belts along plate boundaries.
2-The largest belt runs around the
Pacific Ocean, near convergent
boundaries.
3-Many volcanoes are found either along
the edge of the North American and South
American continents or form volcanic
islands in the Pacific Ocean.
4-There are some volcanoes along the
northern part of the Mid-Atlantic Ridge.
5-Some volcanoes are located far from plate boundaries such as the
Hawaiian hotspot in the Pacific Ocean.
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Be able to name the features produced at each
type of boundary and to explain how they are
formed.
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Depending on the direction of the
convection currents in the mantle, the
plates can move
• Towards each other (convergent)
• Away from each other (divergent)
• Slide past each other (transform)
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Divergent or constructive boundaries
6- Earthquakes
are caused by
volcanic
eruptions or by
plates moving
apart.
5-Submarine
volcanoes appear
along the ridge. Some
may grow to form
volcanic islands, e.g.
Iceland.
Oceanic crust
3-As the plates move apart,
magma from the mantle rises to
fill the gap and forms new oceanic
crust.
4-A mid-ocean ridge is
formed by the new crust.
2-This leads to
a gap being
formed in the
crust.
Oceanic crust
1-Convection
currents pull
plates apart.
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Describe and explain the characteristic features
of a constructive boundary. (4)
What are the features? Mid-ocean ridges, volcanic
islands and earthquakes are the features of a
constructive boundary.
The question asks for an explanation , i.e. the reasons for
these features.
You may answer this question using the ‘case study’, i.e.
located example, of the Mid-Atlantic constructive
boundary.
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Destructive/Convergent
boundaries
A- Oceanic-continental boundaries
B- Continental-continental boundaries
C- Oceanic-oceanic boundaries
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Ocean-to-continent boundary
7-The collision causes
folding and uplift of
rocks which form fold
mountains.
1-The Nazca
Plate and the
South
American Plate
move towards
each other due
to convection
currents.
6-The Peru-Chile
trench
forms where the
oceanic plate is
being
subducted.
5-The melting plate
creates lighter
magma that rises
towards the surface
to form volcanoes.
Andes fold mountains
Pacific
Ocean
Trench
Volcano
South American
Plate (Continental)
Nazca Plate
(Oceanic)
Mantle
2-The Nazca Plate
(oceanic) is being
subducted below
the South
American Plate
(continental).
Subduction
zone
Earthquakes
3-Friction and pressure
cause earthquakes to
occur along the subduction
zone
4-The heat from
the mantle causes
the oceanic plate
to be destroyed.
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b- Continental-to-continental boundary
4- However,
earthquakes
occur due to the
collision of the
plates.
2- This results in
intense folding and
uplift and leads to
the formation of
fold mountains.
3- There is no
subduction. Therefore,
there are no volcanoes.
1- When two
continental plates
meet at a
destructive
boundary, a slow
collision takes place
as both plates have
a low density.
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Ocean-to-ocean boundaries
4- As the Philippine plate
begins to melt, magma
escapes to the surface to
form volcanoes, a few
kilometres from the
trench.
5- After several eruptions, these
volcanoes break the ocean surface to
form islands
Ryuku Islands (Japan)
Philippine Plate
EurasianPlate
Subduction zone
1- Due to convection
currents in the mantle,
the two oceanic plates
collide.
6- When several
volcanic islands form
together they are
called an island arc.
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3- As it is subducted, friction and
pressure cause earthquakes
along the subduction zone.
2-The Philippine Plate is
subducted beneath the
Eurasian Plate.
Conservative [transform] boundaries
Plates just slide past each other with crust neither created nor
destroyed.
Friction builds up and energy is released when the plates move
forward, causing earthquakes.
The San Andreas Fault in
California marks the
junction of the North
American and Pacific plates.
Both plates are moving
north-west but at different
speeds. Instead of slipping
smoothly past each other,
they tend to ‘stick’. The
pressure builds up until
suddenly the plates move
forward and an earthquake
occurs.
There is no volcanic action
because the crust is not being
destroyed.
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