Download Rift valleys and block mountains - Greendale Humaniacs

Fold mountains
• Over millions of years, the folding of rocks creates a
landform called fold mountains.
• The Himalayas, the Rocky Mountains and the Andes
are examples of fold mountains.
Fold mountains
• At convergent plate boundaries, the tectonic plates
converge and collide.
• The compressional force creates immerse pressure.
• Rock layers buckle and fold. (folding)
• Results in the uplifting and compression of Earth’s
crust, forming fold mountain
Fold mountains - Diagrams
Buckle and fold – Fold
Mountain
Compressional Force
Compressional Force
Fold mountains
The Himalayas
Peak : Mount Everest (between
Nepal and Tibet)
Elevation : 8,848 metres
Fold mountains
• Fold mountains are located along convergent plate
boundaries
Fold mountains - Revision
1. Fig. 1 shows a landform.
Identify the landform formed as a result of the convergence and explain
its formation. [5m]
Fold mountains - Revision
1. Fig. 1 shows a landform. Identify the landform formed
as a result of the convergence and explain its formation.
[5m]
• Fold mountain
• At convergent plate boundaries, the tectonic plates converge
and collide.
• The compressional force creates immerse pressure
• Rock layers buckle and fold. (folding)
• Result in the uplifting and compression of Earth’s crust –
forming fold mountain
Fold mountains - Revision
2. Fig. 2 shows a landform.
Fold Mountain A
Identify Fold mountain A, and explain its formation. [5m]
Fold mountains - Revision
2. Fig. 2 shows a landform. Identify Fold mountain A, and
explain its formation. [5m]
• Himalayas fold mountain
• At convergent plate boundaries, Indian-Australian plate and
Eurasian Plate converge and collide.
• The compressional force creates immerse pressure
• Rock layers buckle and fold. (folding)
• Result in the uplifting and compression of Earth’s crust –
forming the Huimalayas fold mountain
Rift valleys and block mountains
• Rift valleys and block mountains are formed at
divergent plate boundaries.
Rift valleys and block mountains
• A fault is a fracture in the rocks along which
the rocks are displaced.
• The tensional forces result in parts of the
crust being fractured.
• This process is called faulting.
Rift valleys
• A rift valley is a valley with steep sides formed along
fault lines.
• E.g. East African Rift Valley
Rift valleys
• It is formed at a divergent plate boundary when
two plates move away from each other.
• The central block of land subsides (sinks) between
two parallel faults due to tensional forces.
• A rift valley, which is a valley with steep sides is
formed.
Block mountains
• A block mountain is a block of land with steep sides.
Block mountains
• It is formed at a divergent plate boundary when
two plates move away from each other.
• When the crusts on either side of the normal faults
move apart, they sink and leave the central block
standing higher than the rest.
• This forms a block mountain, which is a block of
land with steep sides.
Rift valleys and block mountains
The East African Rift Valley
Is formed from the Nubian
section of the African Plate and
the Somalian section of the
African Plate pulling away from
one another.
Rift valleys and block mountains
3. Fig. 3 shows a landform.
A
Identify the landform formed as a result of the plate
movement.
Name landform A and explain its formation. [5]
Rift valleys and block mountains
3. Fig. 3 shows a landform. Identify the landform
formed as a result of the plate movement. Name
landform A and explain its formation. [7]
• Rift Valley
• East African Rift Valley
• It is formed at a divergent plate boundary when
African Plate move away from Somali sub-plate.
• The central block of land subsides (sinks) between
two parallel faults due to tensional forces.
• East African Rift Valley, which is a valley with steep
sides is formed.
Rift valleys and block mountains
4. With the help of well-annotated diagrams, explain
the formation of a block mountain. [5m]
Rift valleys and block mountains
5. With the aid of well-annotated diagrams, explain the
formation of a rift valley. [5]
What phenomena are found at plate
boundaries and how are they formed?
• An earthquake is a vibration in the earth’s crust caused by the
sudden release of stored energy in the rocks found along
fault lines.
Earthquakes
• Extent of earthquakes
- The Richter Scale is used to measure the magnitude
of an earthquake
Earthquakes
• Apart from its magnitude, the extent of damage
caused by an earthquake may vary based on other
factors:
-
Population density
time of occurrence
level of preparedness
distance from the epicentre
type of soil
Earthquakes
The distribution of the earth’s major earthquakes
Earthquakes
• Measuring earthquakes
- A seismograph records the seismic waves released
by an earthquake.
Earthquakes
Hazards associated with living in earthquakes zones
- Threat of tsunamis
- Disruption of services
- Fires
- Landslides
- Destruction of properties
- Destruction of infrastructure
- Loss of lives
Hazards associated with earthquakes
Threat of tsunamis
• Tsunami refers to an usually large sea wave.
• Tsunamis may be formed by:
- The movement of the sea floor during a large earthquake
at subduction zones;
- An underwater volcanic eruption;
- An underwater landslide; and
- A landslide above sea level which causes materials to
plunge into the water.
Hazards associated with earthquakes
Hazards associated with earthquakes
• In 2004, a 9.2 magnitude triggered a tsunami with
waves spreading throughout the Indian Ocean.
Aceh before and after the tsunami hit the area
Hazards associated with earthquakes
The spread of the tsunami waves caused by the tsunami
Hazards associated with earthquakes
Disruption of services
• An earthquake can disrupt services such as the
supply of electricity, gas and water.
• The earthquake in Kobe, Japan, in 1995 disrupted
electricity, gas and water supplies to about a million
of Kobe city’s 1.4 million residents.
Fire
• Earthquakes may rupture gas pipes and this can
provide fuel to start fires.
• For example, the earthquake in Kobe, Japan, in 1995
caused extensive fires.
Hazards associated with earthquakes
Landslides
• Landslides are rapid downslope movements of soil,
rock and vegetation.
• Mudflows may also occur when there is heavy
rainfall.
Destruction of properties
• Earthquakes can cause destruction to many homes.
• People may be without homes after the disaster.
Hazards associated with earthquakes
Destruction of infrastructure
• Earthquakes may cause cracks to form in
infrastructure such as roads and bridges.
• Transportation can be disrupted as it is unsafe to use
the damaged roads.
Hazards associated with earthquakes