Landforms of the Earth

Choose the correct option

Question 1

The forces responsible for the formation of fold mountains:

1. Orogenic movements
2. Collisional movements
3. Diastrophic movements
4. Exogenic movements

Answer

Orogenic movements

Question 2

The large scale uplift or subsistence of land:

1. Orogenic movements
2. Diastrophic forces
3. Epeirogenic movements
4. Exogenic movements

Answer

Epeirogenic movements

Question 3

The two forces, Orogenic and Epeirogenic that originate deep inside the earth:

1. Exogenic forces
2. Continent building movements
3. Diastrophic forces
4. Collisional movements

Answer

Diastrophic forces

Question 4

The forces operating on the surface of the earth which cause formation of landforms are called:

1. Exogenic forces
2. Orogenic forces
3. Diastrophic forces
4. Epeirogenic forces

Answer

Exogenic forces

Question 5

Upfold : Anticline :: Downfold : ................

1. Synclines
2. Archlines
3. Anticlines
4. Ridges

Answer

Synclines

Question 6

Oceanic trenches in combination with volcanic mountain systems lead to the formation of:

1. Troughs
2. Ridges
3. Fold mountains
4. Synclines

Answer

Ridges

Question 7

Volcanic activities are common in which of the following?

1. Young fold mountains
2. Old fold mountains
3. Residual mountains
4. Volcanic plateaus

Answer

Young fold mountains

Question 8

Which amongst the following are highly eroded by the agents of gradation and have gentler slopes, rounded tops and sculptured domes?

1. Young fold mountains
2. Old fold mountains
3. Residual mountains
4. Volcanic plateaus

Answer

Old fold mountains

Question 9

Mountains which are subjected to weathering and erosion for a long time are lowered down:

1. Old fold mountains
2. Volcanic plateaus
3. Relict mountains
4. Intermontane plateaus

Answer

Relict mountains

Question 10

Which of the following are correctly matched?

1. Young fold mountains: Himalayas, Alps
2. Old fold mountains : Urals, Aravalli
3. Residual mountains : Nilgiri, Rajmahal Hills
4. All of the above.

Answer

All of the above

Question 11

The plains that are formed by the deposition of materials which have been brought by various agents of transportation:

1. Structural plain
2. Depositional plain
3. Plain
4. Landform

Answer

Depositional plain

Question 12

A piece of land reclaimed from the sea or lake:

1. Sealand
2. Iceland
3. Lakeland
4. Polder

Answer

Polder

Question 13

The plains that are formed due to uplift or subsidence of land are called:

1. Structural plain
2. Depositional plain
3. Plain
4. Landform

Answer

Structural plain

Question 14

Which of the following pairs is incorrectly matched?

1. Structural Plains : Coromandel Plains
2. Wind Deposition Plains : Thar Desert
3. River Deposition Plains : Northern Plains (India)
4. Marine Deposition Plains : Western Coastal Plains (India)

Answer

Marine Deposition Plains : Western Coastal Plains (India)

Short Answer Questions

Question 1

What is meant by a landform? Give two examples.

Answer

A landform is a natural feature on the surface of the earth. For example- mountains, plateaus.

Question 2

Why are the fold mountains called so?

Answer

Fold mountains are the result of large scale earth movements caused by stresses in the earth’s crust. Such stresses may be caused by weight of the overlying rocks, movements in the mantle, the expansion or contraction of some part of the earth, etc. These stresses subject the rocks to compressive forces, producing wrinkling or folding along the lines of weakness. Hence, these mountains are called fold mountains.

Question 3

Give two chief characteristics of the fold mountains.

Answer

Two chief characteristics of the fold mountains are-

1. The fold mountain system has parallel ranges.
2. A fold mountain region is also a region of sudden forces such as of volcanoes and earthquakes.

Question 4

Give one example of each:

(a) Young fold mountain.
(b) Old fold mountain.

Answer

(a) Young fold mountain - The Himalayas
(b) Old fold mountain - The Aravallis

Question 5

Give one example of residual mountain and an example of depositional plain.

Answer

An example of residual mountain - Nilgiri mountains
An example of depositional plain - Northern plains of India

Question 6

Draw a well labelled diagram to show the formation of a residual mountain.

Answer

Question 7

How is a rift valley formed? Give one example of a rift valley.

Answer

If there are two parallel faults, the valley floor may sink and a rift valley is formed. For example- African Rift Valley.

Question 8

Give a brief definition of a plateau.

Answer

Plateau is defined as an area of high ground, 500 feet above the ground level. Plateaus have steep slope on one side. The upper part is generally flat and is called tableland.

Question 9

What is an intermontane plateau? Give one example.

Answer

The plateaus surrounded by hills and mountains on all sides are called intermontane plateaus. For example- Tibetan plateau.

Question 10

Give two points of importance of landforms.

Answer

The importance of landforms are-

1. The mountain ranges of the world are the abode of snow and glaciers. They are thus the source of perennial rivers.
2. Mountains, plateaus, plains and valleys are beautiful sculptures of nature on the surface of the earth. They add to the beauty of the earth.

Distinguish between each of the following

Question 1

Fold Mountains and Block Mountains.

Answer

Question 2

Intermontane plateaus and Volcanic plateaus.

Answer

Question 3

Structural plains and Depositional plains.

Answer

Structured Questions

Question 1(a)

How are various landforms formed on the surface of the earth?

Answer

Landforms are formed on the surface of the earth due to the following natural processes-

1. Plate Tectonics — The tectonic plates push, collide and slide past each other due to which sedimentary rocks are compressed. This causes folding of the rocks and forms fold mountains.

2. Uplift and Submergence — A set of forces operates inside the earth's centre to the surface and is characterized by large scale uplift and subsidence of land area. These forces result in the formation of block mountains, basins, rift valleys, plateaus, plains, lakes and big faults.

3. Exogenic Forces — These forces cause widespread destruction through weathering and erosion of existing landforms and form new landforms through both erosion and deposition.

Question 1(b)

Describe the formation of mountains and their types.

Answer

A mountain is a very steep land or hill rising to great heights above the land surrounding it. Mountains are classified into three types based on the forces that have formed them.

1. Fold mountains — Fold mountains are the result of large-scale earth movements caused by stresses in the earth’s crust. Such stresses may be caused by weight of the overlying rocks, movements in the mantle, the expansion or contraction of some part of the earth, etc. These stresses subject the rocks to compressive forces, producing wrinkling or folding along the lines of weakness. For example- the Himalayas in India.

2. Residual Mountains — Mountains which are subjected to weathering and erosion for a longtime, are lowered down and called residual or relict mountains. Denudation and erosion by natural agents like winds, water, snow etc., cause the mountains to be lowered but some resistant areas may remain and form residual mountains. They may also be formed on plateaus that are dissected by rivers. For example- Nilgiri in India.

3. Block Mountains — It is an uplifted land mass situated between two adjacent faults. The central block is upthrown or land on the outer-sides of the faults is downthrown so that the central mass appears like a highland. Its surface is like a plateau, but it has steep edges. For example- Vosges in Europe.

Question 1(c)

Give a reason for each of the following:

(i) Asthenosphere though underneath the crust is in a semi-molten state.
(ii) Exogenic forces are also called destructive forces.
(iii) Residual mountains are also called mountains of denudation.

Answer

(i) The internal heat of the earth doesn't travel to the surface because rocks are bad conductors of heat. The internal heat of the earth melts the rocks and keeps the asthenosphere in a semi-molten state.

(ii) Exogenic forces are also called destructive forces because they cause widespread destruction through weathering and erosion of existing landforms.

(iii) Residual mountains are also called mountains of denudation as they are formed due to denudation and erosion by natural agents such as winds, water, snow etc.

Question 1(d)

Draw a well labelled diagram to show the formation of block mountain.

Answer

Question 2(a)

Describe the characteristics of two different types of plateaus.

Answer

The characteristics of Intermontane plateau are-

1. These plateaus are surrounded by hills and mountains on all sides.
2. They are formed along with fold mountains.
   For example- the Tibetan plateau.

The characteristics of Volcanic plateaus are-

1. They are formed by numerous volcanic eruptions that slowly build up over time, forming a plateau.
   For example- the Peninsular Plateau of India.

Question 2(b)

Describe the characteristics of structural plains.

Answer

The characteristics of structural plains are-

1. These plains are formed due to uplift or subsidence of land.
2. Diastrophic forces may cause uplift of a portion of land beneath the ocean water or may cause submergence of coastal land under ocean water.
3. For example- The Great Plains of USA were formed due to the uplift of land submerged under water while the Coromandal plains in India are a result of mild submergence followed by sedimentation.

Question 2(c)

Give a reason for each of the following:

(i) There are different types of plains.
(ii) Alluvial plains are regarded as the granaries of the world.
(iii) The landforms on the surface of the earth are symbols of the energy of the earth.

Answer

(i) There are different types of plain based on the way they are formed. While some have been formed due to depositional activities of rivers and winds, some are formed due to the upliftment and submergence of lands.

(ii) Alluvial plains are regarded as the granaries of the world because they are formed by the deposition of rivers. So, the soil in these plains is very fertile and supports agriculture.

(iii) The landforms on the surface of the earth are symbols of the energy of the earth as they are basically a result of enormous heat generated inside the earth and climate factors operating on the surface of the earth.

Question 2(d)

Explain the chief characteristics of depositional plains and their types.

Answer

Depositional plains are formed by the deposition of materials which have been brought by various agents of transportation. Depositional plains are of three types-

1. River Deposition — The most widespread of these are alluvial plains like the Northern Plains of India; the flood plains like the Mississippi Plains in the USA, deltaic plains in Egypt and India.

2. Wind Deposition — Most such plains are sandy deserts like the Sahara in Africa and the Thar desert in India. They have irregular and undulating surface made by existence of sand dunes and hallows. Loess plains in China are formed from deserts.

3. Marine Deposition — These plains are found in coastal regions. Examples are the east coast of India, the estuarine banks in the Netherlands, coast of Germany and Denmark.

Thinking Skills

Question 1

Find out the landforms found in your state. How were these landforms formed? How many changes have come in these landforms over the years.

Answer

My state is in Northern India. It is home to a variety of landforms that have been shaped by both natural and human processes. These include the vast alluvial plain of the Indo-Gangetic region, the Himalayan foothills, and the valleys, deltas, and floodplains formed by major rivers such as the Ganges, Yamuna, and Ghaghara.

These landforms have been shaped by erosion, sedimentation, and tectonic activity over millions of years, while human activities such as deforestation, agriculture, and urbanization have caused changes to the landscape over time.

Question 2

The earth releases its energy through tectonic activity, earthquakes and volcanoes. Imagine what will be the consequences if this energy remains trapped inside the earth. State these consequences with examples.

Answer

If the energy released through tectonic activity, earthquakes, and volcanoes were trapped inside the Earth, it could lead to a buildup of pressure and result in catastrophic consequences.

For example, if the pressure were to build up within a volcano, it could potentially cause a violent eruption, releasing huge amounts of ash, lava, and toxic gases into the surrounding environment, which could lead to widespread destruction of property and loss of life. The 1815 eruption of Mount Tambora in Indonesia was caused by a buildup of pressure within the volcano, resulting in one of the largest volcanic eruptions in recorded history, with devastating consequences for the region.

Similarly, if the pressure were to build up along a tectonic plate boundary, it could lead to a massive earthquake, causing severe damage to buildings, infrastructure, and other vital structures, resulting in significant loss of life and property damage.

Volcanic activity releases gases such as carbon dioxide, sulphur dioxide, and water vapour into the atmosphere, which can have a significant impact on global climate. If this energy is not released, it can lead to changes in the Earth's climate and ecosystem, affecting agriculture, wildlife, and human populations.