HWA CHONG INSTITUTION
Sec 3 IHE – Geography
T1 Class Test
Name: __________________________ (
) Class: 3A2
Date 24 /02 /14
Parent’s Signature: ________________________
Topic: Geomorphology
____/25m
Section A: Data Response and Field Techniques (10m)
Fig. 1 shows details of major plate boundaries.
B
C
A
Fig. 1
1
a)
With the aid of a well-labelled diagram, explain the formation of fold
mountains in A.
[4]
b)
Compare the characteristics of volcanoes found in B and C.
[4]
c)
Explain the mechanism that makes the plates move in C.
[2]
Sec 3/ IHE Geog 2014/ Chan ML
Section B: Structured and Open Ended Questions (15m)
1)
Explain the formation of the East African Rift Valley.
[3]
2)
Account for the presence of and risks of hydrothermal activity in the
Yellowstone National Park area.
[4]
“The risks of volcanic eruptions certainly discourage people from building
their settlement near active volcanoes.” How far do you agree with this
statement? Explain your answer.
[8]
3)
Source Acknowledgement:
1a)
Fig. A
UCLA
Sec 3/ IHE Geog 2014/ Chan ML
Answers
1 a)
With the aid of a well-labelled diagram, explain the formation of fold
mountains in A.
Marks (1/2m) each:
 Plate movement:
convergent
 Names of plates: S.
American and Nazca Plate
 Compression/Sediments
folded
 Fold Mtns
Ocean
Nazca




b)
S.Am.
S. American (Continental) plate converges w/ the Nazca Plate
Nazca Plate subducts beneath the S. American Plate
Compressing the sediments from the ocean floor
Sediments contorted and lifted to great heights forming the Andes Mtns
Compare the characteristics of volcanoes found in B and C.
B




[4]
Process
Convection currents rise,

causing the N. Am and
Eurasian plates to move

away from each other
Magma rises through the
cracks
Causing sea-floor
spreading, where new
basaltic magma wells up,
cools and solidifies to
become the new sea floor

As the plate continues to
move apart, the older
mountains move away from
the spreading zone

Sec 3/ IHE Geog 2014/ Chan ML
C
Convection currents sink,
causing the plates to collide
Indo-Australian and Pacific
Plate converge
The thinner and denser
oceanic descends beneath
the continental plate:
subduction occurs
As the oceanic plate is
[4]






The younger are closest to
the spreading zone
There’s no subduction
Landforms
Volcanic islands (Iceland,

Surtsey Island)
Submarine rift volcanoes

Basaltic lava
Gentle eruption in
comparison to C
c)







subducted into the mantle,
the plate is destroyed
The melting of subducting
plate produces silica-rich
magma
It moves along cracks or
fractures and escapes
through vents to the land
surface, forming a chain of
volcanoes subduction
volcanoes
Volcanoes are steep and tall,
Viscous lava
Violent eruption
Explain the mechanism that makes the plates move in C.
[2]
Convection currents: movement within the mantle
Material expand, rise and spread out beneath the plates, causing the plates
to be dragged along
Cools and sinks, dragging plates along
Move towards each other
Section B: Structured and Open Ended Questions (15m)
1)
Explain the formation of the East African Rift Valley.
 In areas with divergent plates,
 normal faults are formed (1m)
 Due to tensional forces
 The central block subsides between the two parallel faults
 Valley with steep sides is formed
[3]
2)
Account for the presence of and risks of hydrothermal activity in the
Yellowstone National Park area.
Presence
 Hotspot area
 Magma comes from the mantle,
 Vast amount of viscous magma moving to the surface through
fractures
 OR: Magma in the magma chamber heats up the water causing
them to escape on the surface under immense pressure
(gysers)
[4]
Sec 3/ IHE Geog 2014/ Chan ML





3)
Risks:
Major eruption may occur, VEI 8
Regional and global proportions: would have an impact on the
climate (block the sunlight, lower the temperature)
Animals, crops and people of immediate surrounding area
would die
Mass starvation, mass evacuation,
Great impact on the world economy
“The risks of volcanic eruptions certainly discourages people from building
their settlement near active volcanoes.” How far do you agree with this
statement? Explain your answer.
[8]
Answer Scheme for Open Ended Question:
P1 Yes, people choose to live in volcanic areas due to the economic benefits
(Agriculture)
E
Elaborate your answer…
E
L
Give examples (and explain) on countries where violent eruption caused
destruction (you may have 1 or 2 examples)
 Mt Etna: ash weathers into fertile soil = ideal for farming in the
surroundings of Mt. Etna
 Nyiragongo: farmers benefit from the fertile soil – subsistence farming
 Java and Bali, Indonesia: supports the cultivation of crops: tea, coffee and
rice – due to the most fertile soil area
 Mt. Pinatubo: ideal for rice growing: the volcano has not erupted since
1380 – so it has been a long term benefit
 In the 1991 eruption destroyed all crops on adjacent farmland, water
supplies were cut off and became contaminated, buildings, roads,
factories were completely destroyed.
 Not only did the eruption ruined the harvest in 1991, it made it
impossible for 1992
 1 million farm animals died due to starvation (lack of grass)
 Displacement of thousands of farmers and family
Link back to the Qn: therefore, though the returns of good harvest attracted
farmers to settle in the area, all was destroyed after the eruption.
P2
Other economic activities, such as tourism are examples of long term benefits
Because…
Elaborate your answer…
 Geysers and volcanoes in Yellowstone Nat Park generates tremendous
Sec 3/ IHE Geog 2014/ Chan ML
E

E







L
amount of revenue through tourists who visit the park every year (both
local and foreign)
Hot springs – are good for health, very popular in Korea and Japan
(tourism)
Precious stones: Kimberley in S. Africa (diamond trade)
The ruins of Pompeii, Italy (popular tourist attraction): more than 3 million
people visit the site every year
Geothermal energy: Iceland – alternative energy: 70% of homes are
heated by volcanic steam
Warnings of volcanic eruptions will keep tourists away
Ashes and lahars will destroy the infrastructure and roads, making it
inaccessible and unsafe for tourists
The after-effect may be long term as it takes time to rebuild the area or
attractions
Ash cloud from the Icelandic and Chilean volcanoes prevented / disrupted
flights within the region – not only locals were affected, flights to
neighbouring countries were also hindered
Link back to the Qn: therefore, though the returns to the economy attracted
many people to settle in the area, together with their buildings and industries, to
be destroyed by the eruption.
Environmental impact is important because the eruption can emit a tremendous
amount of gases and particles which will be suspended in the atmosphere for a
P3
long time, affecting not only the local area, but the region.
E
E
L
Elaborate your answer…
 The long term effect of ash in the atmosphere can also be observed in the
weather
 Temperature measure after Mt. Pinatubo’s eruption showed that the
average global temperature declined, causing a cooling effect. Though
Pinatubo delayed global warming for several years, it is interesting to note
that is may have a negative impact on the ozone layer
 The particles containing sulphur remains suspended in the atmosphere for
several years
 They are important / contributes to the destruction of the ozone; enhancing
ozone loss
Link back to the Qn: Many people overlook the impact of eruptions on the
environment.
Conclusion: The long term benefits of living near volcanic areas far
Sec 3/ IHE Geog 2014/ Chan ML
outweigh the risks and destruction caused by an eruption, which may not
happen. Ironically the feature which benefits the population and area may
also bring destruction.
Sec 3/ IHE Geog 2014/ Chan ML