Download PAST HKCEE -Mountain Building Processes

SFCC/Past HKCEE
P.1
Mountain Building Processes
(Suggested Answers)
General reminders:
1. Study the maps:
the distribution and movement of the plates (Refer to Fig.2.5 on P.21)
the distribution of main zones of vulcanicity (Refer to Fig.2.21 on P.30)
the distribution of young and old fold mountains (Refer to Fig.3.2 on P.36)
2.
Plate boundaries and their associated features (MC questions)
Destructive plate boundary
Constructive plate boundary
Plates converge / collide / subduct Plates diverge / move apart
Compressional force
Conservative plate boundary
Plates slide against
Tensional force
Tangential force
Faulting
Reverse fault
Block mountain
Rift valley
Faulting
Normal fault
Block mountain
Rift valley
Faulting
Tear fault
(San Andreas Fault in California)
Earthquakes
Earthquakes
Earthquakes
Vulcanicity
Vulcanicity
Oceanic trench
Mid-oceanic ridge
Folding
Young fold mountains
Old fold mountains
3.
4.
5.
Formation of fold mountains is asked frequently (Long Questions)
Remember to study Earthquakes and movement of the plates together
Draw annotated diagrams to answer the questions
HKCEE 1989 Volcano
1a. Identify this type of mountain. (1)
Reminder:
-Where is mountain X? What type of mountain can be found in Philippines?
Volcano
b. Describe the appearance of the mountain. (4)
Reminder:
-base on Figure 1a and describe it
Tall and conical in shape
Wide-base with steep slopes
A carter at the top of the mountain
Little vegetation is found on the sides of the mt.
Explain the formation of the mountain in relation to plate movements. (12)
Reminders:
-What types of plate movement will lead to the formation of volcano?
Destructive & Constructive
-Then, study Figure 1b and identify the direction of the arrows.
-Which two plates collide? Which one is denser?
SFCC/Past HKCEE
P.2
The denser Pacific Plate / Philippine Plate collide with the Eurasian Plate because of
compressional force of sinking convection current in the upper mantle. The oceanic plate,
which is made up of heavy material, is subducted beneath the continental plate along the
destructive plate boundary. At the subduction zone, an oceanic trench is formed. The
Philippine Trench is a good example formed by subduction.
When the oceanic plate is pushed into the mantle which has high temperature and
pressure, it is melted to form magma. The magma is lighter than the mantle. It is ejected
out onto the land surface through the lines of weakness / faults due to release of pressure.
Under violent eruption, a cone is formed with alternate layers of ash and lava. It is built
higher under repeated eruption. As a result, a chain of volcanic islands may be developed
along the plate boundary.
1d. What kinds of natural hazards might be associated with this type of mountain? (4)
Reminder:
-Don’t mention fold mt, block mt and rift valley. Why? They are not natural hazards
Earthquakes
Poisonous gases emission
Landslide
Fire hazards
HKCEE 1991 Fold mountain
2ai. Name the type of plate boundary (1).
Reminder:
-Identify the direction of the arrows
Destructive plate boundary
2aii. Describe and explain the movement of plates in the figure (4)
Reminder:
-Describe = What; Explain = Why
Re-phrase the question: What is the plate movement? Why is it like this?
Describe:
One plate collides with the other.
Explain:
It is because of the compressional force of sinking convection current in the upper mantle.
The oceanic plate, which is made up of heavy material, is subducted beneath the
continental plate along the destructive plate boundary.
2bi. What kind of mountain range would form along this kind of plate boundary? Name
one example. (2)
fold mountain e.g. the Andes / the Rockies
2bii. Describe the characteristics and formation of this type of mountain range. (10)
Re-phrase the question: What are the characteristics of fold mt.? How is it formed?
Characteristics
Parallel ranges / in mt. belt
Along the plate boundaries
Made up of sedimentary rock Rock strata are folded
Steep slopes / rugged relief
Uplifted to great height
SFCC/Past HKCEE
P.3
Formation
The weathered sediments from the continental plate are brought by the erosive agents e.g.
wind & river, and deposited in the oceanic trench. The accumulated sediments are then
compressed into sedimentary rocks. When plates collide together, compressional force is
generated. Folding occurs and leads to the uplift of the rock strata. Fold mountain is
formed and is often associated with volcanic activity.
S
2c. What other tectonic activities may occur along this type of plate boundary? (4)
Vulcanicity / volcanic eruption
Earthquakes
Faulting
Folding
HKCEE 1993 Fold mountain
1ai. Name the zones marked P and Q. (2)
P: Mantle
Q: Core
1aii. What are the characteristics of zone P? (3)
Partly molten
Less dense than core
High temperature
Presence of convection current
Contains iron / magnesium
Basic rocks
1b. The Alps represents a type of mountain. Describe the characteristics of this type of
mountain. (5)
Reminder:
-Alps is a young fold mountain.
Re-phrase the question: What are the characteristics of fold mountain?
Parallel ranges / in mt. belt
Along the plate boundaries
Made up of sedimentary rock Rock strata are folded
Steep slopes / rugged relief
Uplifted to great height
Young fold mountain
1c. How do physical processes help to lower the relief of mountains? (7)
Reminder:
-Denudation: weathering, erosion and mass movement-> lower the relief of mt.
Re-phrase the question: Why is the relief of mountains lowered?
The relief of mountains is mainly lowered by denudation. With repeated expansion and
contraction of cracks, rocks are broken down. This process is called weathering E.g.
block disintegration, exfoliation.
Then, the weathered materials are transported down slope under the influence of gravity.
This process is called mass wasting. E.g. landslide, rock fall.
Finally, the weathered materials are further removed and broken by erosive agents such as
wind and river. This process is called erosion.
1d. What might be the benefits of mountains to human activities? (4)
Re-phrase the question: What are the benefits bought by fold mt?
Provide shelter against winds
Rainfall on windward slope
Provide site for H.E.P. development
Timber resources
Educational
Recreation / tourism
SFCC/Past HKCEE
P.4
HKCEE 1996 Fold mountain
1a. Name the type of plate boundary labeled X and Y respectively. (2)
X: destructive plate boundary
Y: constructive plate boundary
1b. Describe the characteristics of plate boundary Y. (3)
Spreading / constructive zone
Ocean floor move apart
Magma rise up to form new ocean floor
Presence of oceanic ridges
The rocks near ridges are younger than on both sides
1c. Explain the formation of mountains along plate boundary X in relation to plate
movements. (9)
Reminder:
-Fold mountain or volcano can be found in plate boundary X. According to the location
(Figure 1), fold mountain is found there.
Two plates are colliding because of compressional force of sinking convection current in
the upper mantle. The oceanic plate, which is made up of heavy material, is subducted
beneath the continental plate along the destructive plate boundary. At the subduction zone,
an oceanic trench is formed.
The weathered sediments from the continental plate are brought by the erosive agents e.g.
wind & river, and deposited in the oceanic trench. The accumulated sediments are then
compressed into sedimentary rocks. When plates collide together, compressional force is
generated. Folding occurs and leads to the uplift of the rock strata. Fold mountain is
formed and is often associated with volcanic activity.
1di. Vulcanicity often occurs in the mountain areas of X. Name two other crustal
movements that may take place. (2)
Faulting
Folding
1dii. What benefits may Vulcanicity bring to human beings? (3)
Fertile soils
Hot springs . tourism
Mineral resource e.g. sulphur
Geothermal power