Landforms
1. Choose the correct answer from the given options.
a. This is a young fold mountain in South America:
i) Rockies. [ ]
ii) Himalayas. [ ]
iii) Andes. [✓]
b. This mountain was formed due to faulting:
i) Himalayas. [ ]
ii) Vindhyas. [✓]
iii) Mt. Kilimanjaro. [ ]
c. Deccan plateau is an example of
i) Intermontane plateau. [ ]
ii) Lava plateau. [✓]
iii) Dissected plateau. [ ]
2. State whether the following statements are 'true' or 'false'.
1. Old fold mountains have tall snow covered peaks. [F]
2. The Tibetan plateau is an ancient lava plateau. [F]
3. Plains are very rich in mineral reserves. [F]
4. Rivers are navigable in the plains. [T]
5. Terrace cultivation is done in the mountains. [T]
3. Name the following.
a. One mountain that includes extinct volcanoes.
= Mt. Killimanzaro;
b. The three major ranges of the Himalayas.
= Himadri; Himachal; Siwalik;
c. One of the longest rift valley system of the world.
= The East African Rift Valley System.
d. Minerals found is the Chhota Nagpur Plateau.
= Coal, iron ore, manganese, bauxite and mica.
4. Distinguish between the following.
a. Exogenous and endogenous process.
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Exogenous Process
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Endogenous Process
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i. These processes operate above the Earth’s surface.
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i. These processes take place below the surface of the Earth, in the
interior.
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ii. They include the work of wind, running water, glaciers and
various such agents.
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ii. Folding, faulting and volcanic activities are the major indigenous
processes.
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b. Mountains and plateaus.
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Mountains
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Plateaus
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i. These are land masses that rise steeply to a few thousand metres
above sea level.
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i. These are extensive flat-topped highland with steep sides that
rises abruptly from the surrounding area.
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ii. Mountains are often higher than plateaus.
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ii. Plateaus are often lower than mountains.
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iii. Mountains are snow covered at their peaks.
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iii. Plateaus have broad and flat summit.
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c. Old fold and young fold mountains.
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Old Fold Mountains
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Young Fold Mountains
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i. These are formed several hundred million years ago.
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i. These are formed a few million years ago.
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ii. They have gentle slopes and low rounded peaks.
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ii. They have steep slopes and tall peaks.
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iii. Their peaks are worn away by the agents like river, glaciers
etc.
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iii. Their peaks remain snow covered throughout the year due to high
elevation.
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d. Fold and block mountains.
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Fold Mountains
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Block Mountains
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i. These mountains are formed due to the collision of the plates under
the Earth’s crust.
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i. These mountains are formed due to the tensional forces and faults
of the Earth’s crust.
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ii. They have tall peaks which remain snow covered through the year.
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ii. They have flattened peaks.
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e. Tibetan Plateau and Deccan Plateau.
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Tibetan Plateau
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Deccan Plateau
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i. It is an intermontane plateau.
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i. It is a volcanic or lava plateau.
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ii. It is surrounded by high mountains on all sides.
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ii. It is made up of solid lava sheets.
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iii. It has high elevation. So, it is called the ‘roof of the world’.
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iii. It has comparatively low elevation.
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5. Explain how the following are formed.
a. Fold mountains.
= Fold Mountains are most commonly formed by creasing or buckling of the Earth's crust due to forces of compression. These are thus called fold mountains. This process generally happens when two plates collide or move towards each other. The collision causes the edges of the plates to be raised or uplifted to form mountains.
b. Block mountains and rift valleys.
= Movement of the Earth's crust may sometimes cause or faults to occur, resulting in the crust breaking into blocks. These large blocks of crust are also called crusted blocks.
Cracks or faults most commonly occur due to tensional forces that pull crustal blocks away from each other. As a result, the crustal block in between two fault lines subsides along the fault plane, leaving two raised blocks on either side known as block mountains. The subsided block in between forms a rift valley.
c. Volcanic mountains.
= Volcanic mountains are made up of molten materials known as magma, along with ash and small rock particles called cinders. These materials erupt from the Earth's interior through an opening known as vent. On reaching the surface, the magma cools and solidifies. With several successive eruptions the lava piles up gradually, thereby building up a conical volcanic mountain.
d. Lava plateau.
= Sometimes, magma may come out from long narrow fissures or cracks on the ground instead of a single vent. In such eruptions, the magma spreads over large area and solidifies as lava sheets. When this continues over a long period of time, the lava sheets pile up and form a lava plateau.
e. Dissected plateau.
= When a plateau is transversed by several rivers, deep valleys are cut on the surface by the action of running water. Extensive erosion along these valleys results in the cutting up of the plateau into smaller raised sections, giving its surface an irregular appearance. It is dissected plateau.
6. Give one reason to explain each of the following.
a. Plateaus are also referred to as 'tablelands'.
= Plateaus are also referred to as 'tablelands' because of their broad and flat summit.
b. Old-fold mountains have low, rounded peaks.
= Old-fold mountains have low, rounded peaks since they have been worn down by agents of denudation such as rivers and glaciers over a long period of time.
c. Most fold mountains occur at margin of plates.
= Fold mountains are formed by the collision of two plates which generally causes the edges of the plates to be raised or uplifted to form mountains. Most fold mountains thus occur at margins of plates.
7. Answer the following questions.
a. State the reasons why mountains are important to us.
= Mountains play a very important role in our lives. Let us find how:
i) Glaciers moving down the mountain slopes melt at low altitude and form streams that turn into rivers. Rivers provide water for irrigation, generation of electricity and navigation. They also bring silt to the fertile plains.
ii) Mountains often block moist winds coming from the seas and force them to shed moisture, causing rain. Mountains may also modify the temperature of a place by blocking cold or warm winds.
iii) Mountains are areas of dense vegetation which are home to many animals. Forests are rich reserves of timber and other resources.
iv) Terraces are made on mountain slopes to cultivate crops such as rice and fruits. Crops such as tea and coffee also grow well on hill slopes.
v) Mountains serve as ideal grounds for pasture on which sheep and cattle can graze. Sheep provide us with wool while cattle give us milk, butter and cheese.
vi) Mountains are ideal tourist spots as they are extremely picturesque.
b. How are plateaus beneficial for us?
= Plateaus are beneficial for us in the following ways:
i) Plateaus, especially the ancient ones, are very rich in mineral deposits. Therefore, many mining fields have developed in the Brazilian Plateau of east Africa and the Chhota Nagpur Plateau of India.
ii) Agriculture can be practiced in the lava plateaus as they are made up of fertile black soil.
iii) Rivers such as the Congo and Colorado that descend from the edge of plateau create waterfalls. Water falling from a height is ideal for the hydroelectric power generation.
iv) Some of the plateaus render natural beauty to the landscape and hence have become attractive tourist spots.
c. How are alluvial plains formed?
= Alluvial plains are formed by the deposition of alluvium by rivers.
d. Explain the major differences in the way of life of the people of the mountains and plains.
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Life in the mountains
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Life in the plains
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i. Fewer people live in the difficult terrain.
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i. Plains are usually densely populated.
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ii. Most of the houses are made with wood with slanting roof.
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ii. Most of the houses are made of clay and bricks.
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iii. People wear woollen clothing most of the time.
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iii. People wear light, cotton clothing.
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iv. Cultivation is difficult.
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iv. Plains are fertile and easy to cultivate. Many types of crops are
grown here.
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v. Transport network is not well developed.
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v. There are dense network of roads and railways.
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vi. It is difficult to establish large factories here.
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vi. Large-scale industries are possible in plains.
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vii. Agriculture, handicraft and tourism are common occupations.
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vii. Agriculture industry and trade are important occupations.
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