1. Folding occurs typically at convergent plate boundaries where layers of rock are pushed and compressed
causing rock strata to buckle and fold, forming fold mountains.
Faulting involves the displacement of rock strata along fault lines or large cracks in the Earth’s crust to
form block mountains and rift valleys.
Distribution of…
Fold mountains
Fold mountains are found along convergent plate
boundaries. They are found where two continental
plates collide or where one continental plate
converges with an oceanic plate. There are two
major fold mountain belts. One belt is the Circum
Pacific belt that surrounds the Pacific Ocean. In
the eastern part of the Pacific Ocean, the mountains
are found mainly along the edge of continents such
as the Andes and Rockies. In the western part, they
are found offshore and take the form of island arcs
such as Japan and Philippines. The other belt is the
Mediterranean-North India belt stretching from
northen part of Africa where Atlas mountains are to
Southern Europe where the Alps are to Northern
India where the Himalayas are.
Volcanoes
Volcanoes are mostly found in belts that coincide
with convergent and divergent plate boundaries.
15% of the volcanoes are found at mid-oceanic
ridges and 80% of them are found at subduction
zones all of which are places with high plate
activity. At divergent plate boundaries, basaltic
volcanoes and volcanic islands form on mid-
oceanic ridges or ocean floors. For example,
Iceland and Surtsey Island are on the Mid-Atlantic
Ridge. At convergent plate boundaries, subduction
volcanoes are found especially in the Circum
Pacific region. For example, Mt St Helens on the
Rockies, Philippine Islands and Aleutian Islands.
5% of the world’s volcanoes are formed over hot
spots for example Mauna Loa in Hawaii.
Earthquakes The world’s major earthquakes occur along all 3
plate boundaries – convergent, divergent and
transform – where they represent zones of
instability in the Earth’s crust. One major belt is the
Circum Pacific belt that surrounds the Pacific
Ocean. It coincides with regions with subduction
volcanoes, oceanic trenches and fold mountains.
This accounts for 68-70% of all earthquakes. The
other belt is the Mediterranean-North India belt

2. which stretches from Southern Europe where the
Alps are to Northern India where the Himalayas
are. They account for about 20% of earthquakes.
The 3rd belt is the Mid-Atlantic belt and the East
African Valley where divergence of plates cause
them. This accounts for about 10% of earthquakes.
Formation of rift valleys (I)
Rising and spreading magma generates convectional currents
which result in continental-continental plate divergence of the
(plate name) and (plate name). As the crust continues moving
apart, they are stretched, causing fractures to form near the
boundary. Tensional forces cause normal faults to appear. The
land between the crusts sinks as a result forming a linear
depression known as the rift valley.
Formation of rift valleys (II)
Cooling and sinking magma generates convectional currents which result in
continental-continental plate converge of the (plate name) and the (plate
name). As the crust continues moving together, they are compressed, causing
fractures to form near the boundary. Compressional forces cause reverse
faults to appear. The land beside the faults are raised making the middle block
appear lower. The overhanging escarpments are soon eroded by wind and the
land between the faults form a linear depression known as the rift valley.
Formation of block mountains (I)
Rising and spreading magma generates convectional currents
which result in continental-continental plate divergence of the
(plate name) and (plate name). As the crust continues moving
apart, they are stretched, causing fractures to form near the
boundary. Tensional forces cause normal faults to appear. The
land beside the faults subside making the middle block appear
appear higher. The land left higher is the block mountain.
Formation of block mountains (II)
Cooling and sinking magma generates convectional currents which result in
continental-continental plate converge of the (plate name) and the (plate
name). As the crust continues moving together, they are compressed, causing
fractures to form near the boundary. Compressional forces cause reverse
faults to appear. The land between the faults are raised. The overhanging
escarpments are soon eroded by wind and the land between the faults form a
block mountain.

3. Characteristic Shield volcano Acid volcano Composite volcano
Shape
Gently sloping, flat Steep slopes, narrow Steep slopes at top,
near top, broad base. base. gentle slopes at bottom.
Finer ash and cinder are
blown by wind down
(wind sorting)
Type of lava
Basic lava: low Acid lava: high Acid lava: high
viscosity, high viscosity, low viscosity, low
temperature, take long temperature, take short temperature, take short
time to solidify time to solidify time to solidify
Materials ejected
Gas, steam, basic lava. Acid lava only Acid lava, cinder, ash
that forms alternating
layers.
Type of eruption
Non-violent, basic lava Violent, acid lava Violent, acid lava
travels a long distance travels very little hence travels very little hence
before it solidifies hence it solidifies near the it solidifies near the
it does not clog up the vent, clogging it up. vent, clogging it up.
vent of the volcano Pressure due to gases Pressure due to gases
which means that lava builds up resulting in builds up resulting in
can escape easily. violent eruptions. violent eruptions.
Diagram of volcano, eg
eg. Mauna Loa, Hawaii eg. Mt Mayon, eg. Mt Vesuvius, Italy
Philippines

4. Type of impact Impact Description Example
Lava and pyroclastic People still live at the
material may be slopes of Mt Merapi,
weathered down to form Indonesia as the
Fertile soil for soil for agriculture, pyroclastic materials
agriculture expedited in tropical make the soil near the
areas. Minerals released slopes extremely
make it easy for farmers fertile.
to reap rich harvests.
Vulcanicity may form
precious stones and
Precious stones and minerals such as gold,
-
minerals silver, diamonds etc
enabling mining to be
carried out.
Benefit
Volcanic areas appeal to People in Japan bury
tourists as they would like themselves in
to see volcanic landforms volcanic materials as
and also volcanic hot they believe these
Tourism springs can be converted materials help them to
to health resorts as relax and can cure
mineralised water is some ailments.
believed to have
medicinal value.
Steam produced from hot
underground water in
volcanic areas can be
Geothermal energy harnessed to drive -
turbines to generate
electricity, alternative
source of electricity.
Sulfur dioxide released by
volcanic eruptions react
with oxygen in the air to
form sulfur trioxide
Problem Acid rain which soon reacts with -
water vapour to form
sulfuric acid that mixes
with rainwater to corrode
infrastructure and leaches
soil.

5. Sulfate aerosols may
block incoming solar
radiation, cooling the
troposphere and resulting
in a ‘cooler’ Earth. They
Effects on weather -
also block outgoing heat
radiation from the Earth’s
surface, warming the
stratosphere (enhanced
greenhouse effect)
Large amounts of ash and
Problem
dust extruded during the
volcanic eruption may
pollute the environment,
block the sun and make
day dark, disrupting
transport networks. Ash
Pollution -
may remain in the air
damaging the respiratory
systems of people and
livestock. It may also mix
with water sources hence
reducing available clean
water sources.