Landforms of the Earth - Questions & Answers

I. Choose the correct option:

1. Identify the forces responsible for the formation of fold mountains.
(a) Orogenic movements
(b) Collisional movements
(c) Diastrophic movements
(d) Exogenic movements
Answer: (a) Orogenic movements

2. The large scale uplift or subsidence of land:
(a) Orogenic movements
(b) Diastrophic forces
(c) Epeirogenic movements
(d) Exogenic movements
Answer: (c) Epeirogenic movements

3. The two forces, Orogenic and Epeirogenic that originate deep inside the earth:
(a) Exogenic forces
(b) Continent building movements
(c) Diastrophic forces
(d) Collisional movements
Answer: (c) Diastrophic forces

4. The forces operating on the surface of the earth which cause formation of landforms are called:
(a) Exogenic forces
(b) Orogenic forces
(c) Diastrophic forces
(d) Epeirogenic forces
Answer: (a) Exogenic forces

5. Identify A and B.
(a) A: Anticline B: Archline
(b) A: Syncline B: Anticline
(c) A: Anticline B: Syncline
(d) A: Syncline B: Archline
Answer: (c) A: Anticline B: Syncline

6. Oceanic trenches in combination with volcanic mountain systems lead to the formation of:
(a) Troughs
(b) Ridges
(c) Fold mountains
(d) Synclines
Answer: (b) Ridges

7. Volcanic activities are common in which of the following?
(a) Young fold mountains
(b) Old fold mountains
(c) Residual mountains
(d) Volcanic plateaus
Answer: (a) Young fold mountains

8. Assertion (A): External forces or Exogenic forces are Destructive Forces.
Reason (R): They produce relief such as mountains, plateaus, plains, lakes and big faults.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R does not explain A.
(c) A is true but R is false.
(d) A is false but R is true.
Answer: (c) A is true but R is false.

9. Assertion (A): Residual mountains are also called mountains of denudation.
Reason (R): Denudation and erosion by natural agents cause mountains to be lowered.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R does not explain A.
(c) A is true but R is false.
(d) A is false but R is true.
Answer: (a) Both A and R are true and R is the correct explanation of A.

10. Which amongst the following highlands are highly eroded by the agents of gradation and have gentler slopes, rounded tops and sculptured domes?
(a) Young fold mountains
(b) Old fold mountains
(c) Residual mountains
(d) Volcanic plateaus
Answer: (b) Old fold mountains

11. Mountains which are subjected to weathering and erosion for a long time are lowered down:
(a) Old fold mountains
(b) Volcanic plateaus
(c) Relict mountains
(d) Intermontane plateaus
Answer: (c) Relict mountains

12. Which of the following is/are correctly matched?
(a) Young fold mountains : Himalayas, Alps
(b) Old fold mountains : Urals, Aravalli
(c) Residual mountains : Nilgiri, Rajmahal Hills
(d) All of the above.
Answer: (d) All of the above.

13. Assertion (A): The forces of faulting lead to the formation of block mountains.
Reason (R): Block mountains are often separated by intervening basins called graben.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R does not explain A.
(c) A is true but R is false.
(d) A is false but R is true.
Answer: (b) Both A and R are true but R does not explain A.

14. The Coromandel plains along the east coast of India were formed as a result of two different activities. Name them.
(a) Subsidence, deposition
(b) Subsidence, erosion
(c) Upliftment, deposition
(d) Upliftment, erosion
Answer: (a) Subsidence, deposition

15. The plains that are formed by the deposition of materials which have been brought by various agents of transportation:
(a) Structural plain
(b) Depositional plain
(c) Polder
(d) Dykes
Answer: (b) Depositional plain

16. Depositional plains formed as a result of action of wind have irregular and undulating surface because of
(a) new deposits made every day.
(b) existence of sand dunes and hallows.
(c) existence of scrubs.
(d) All of the above.
Answer: (b) existence of sand dunes and hallows.

17. A piece of land reclaimed from the sea or lake:
(a) Horst
(b) Graben
(c) Dyke
(d) Polder
Answer: (d) Polder

18. The plains that are formed due to uplift or subsidence of land are called:
(a) Structural plains
(b) Depositional plains
(c) Plains
(d) Landforms
Answer: (a) Structural plains

19. Which of the following pairs is incorrectly matched?
(a) Structural Plains : Coromandel Plains
(b) Wind Deposition Plains : Thar Desert
(c) River Deposition Plains : Northern Plains (India)
(d) Marine Deposition Plains : Western Coastal Plains (India)
Answer: (d) Marine Deposition Plains : Western Coastal Plains (India)

20. Epeirogenic forces lead to the formation of Block Mountains. In this context which of the following are true?
(a) Horst - block mountains with flattened summits.
(b) Graben - basins separating block mountains.
(c) Vosges - example of block mountains.
(d) All of the above.
Answer: (d) All of the above.

21. Name the plateaus, formed along with fold mountains, that are surrounded by hills and mountains on all sides.
(a) Volcanic Plateaus
(b) Structural Plateaus
(c) Intermontane Plateaus
(d) Depositional Plateaus
Answer: (c) Intermontane Plateaus

22. Assertion (A): Many lakes exist in the vast lowland of the Great Plains of the USA.
Reason (R): The Great Plains were formed due to uplift of land submerged under water.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R does not explain A.
(c) A is true but R is false.
(d) A is false but R is true.
Answer: (a) Both A and R are true and R is the correct explanation of A.

II. Short Answer Questions

1. What is meant by a landform? Give two examples.
Answer: A landform is a natural feature of the earth's surface. Two examples are mountains and plains.

2. Why are the fold mountains called so?
Answer: They are called fold mountains because they are formed by the lateral compression of sedimentary rocks lying between plates, which causes wrinkling or folding of the rocks into irregular wave-like formations.

3. Give two chief characteristics of the fold mountains.
Answer: (i) They form irregular wave-like formations called folds, consisting of arch-like anticlines and down-folded synclines. (ii) Most are constituted of sedimentary rocks formed due to deposition and consolidation of sediments in shallow oceans.

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.

5. Give one example of residual mountain and an example of depositional plain.
Answer: An example of a residual mountain is the Nilgiri hills (India). An example of a depositional plain is the Northern Plains of India.

6. Briefly describe how the Great Plains of USA were formed. They are examples of which type of Plains.
Answer: The Great Plains of the USA were formed due to the uplift of coastal land that was previously submerged under ocean water. They are examples of Structural Plains.

7. Draw a well labelled diagram to show the formation of a residual mountain.
Answer: (Students are expected to draw a diagram showing an original high plateau being worn down by natural agents like rivers carving out valleys, resulting in steep, eroded residual mountains with lower elevations. See Fig. 5.3 in the textbook.)

8. How is a rift valley formed? Give one example of a rift valley.
Answer: A rift valley is formed due to tensional forces that cause cracks or faults on the earth's crust. If two parallel faults occur, the land in between them subsides, forming a rift valley. An example is the African Rift Valley.

9. Give a brief definition of a plateau.
Answer: A plateau is defined as an area of high ground, 500 feet above the ground level, characterized by a steep slope on one side and a generally flat upper part called a tableland.

10. What is an intermontane plateau? Give one example.
Answer: An intermontane plateau is the highest and most extensive type of plateau that is surrounded by hills and mountains on all sides, formed along with fold mountains. An example is the Tibetan Plateau.

11. Give two points of importance of landforms.
Answer: (i) Mountain ranges are the abode of snow and glaciers, making them the source of perennial rivers. (ii) Landforms like coastal regions and island groups are ideal fishing sites.

III. Distinguish between each of the following:

1. Fold Mountains and Block Mountains.
Answer: Fold mountains are formed by lateral compression (orogenic movements) pushing sedimentary rocks into wrinkles and folds. Block mountains are formed due to tensional forces (epeirogenic movements) causing cracks or faults in the crust, resulting in the uplift or subsidence of land blocks.

2. Intermontane Plateaus and Volcanic Plateaus.
Answer: Intermontane plateaus are formed along with fold mountains and are surrounded by hills and mountains on all sides (e.g., Tibetan plateau). Volcanic plateaus are formed by numerous volcanic eruptions that slowly build up accumulations of lava over time to form a flat, elevated land (e.g., Peninsular Plateau of India).

3. Structural Plains and Depositional Plains.
Answer: Structural plains are formed due to the uplift or subsidence of land caused by large-scale diastrophic forces (e.g., Great Plains of the USA). Depositional plains are formed by the deposition of materials brought and dropped by natural agents like rivers, wind, and marine water over long periods (e.g., Northern Plains of India).

IV. Structured Questions

1. (a) How are various landforms formed on the surface of the earth?
Answer: Landforms are formed by two main types of forces: Endogenic forces (internal processes acting deep inside the earth, including Orogenic mountain-building movements and Epeirogenic continent-building forces) and Exogenic forces (external processes operating on the surface, causing weathering, erosion, and deposition of materials).

(b) Describe the formation of mountains and their types.
Answer: Mountains are steep, highly elevated lands formed by various tectonic activities. They are classified into three types:
1. Fold Mountains: Formed by the lateral compression of the earth's crust, causing rock strata to wrinkle into folds.
2. Block Mountains: Formed due to tensional forces creating faults in the crust; the rising of a land block between faults forms a block mountain.
3. Residual Mountains: Formed when original mountains or plateaus are subjected to weathering and worn down by natural agents over a long time.

(c) Give a reason for each of the following:
(i) Asthenosphere though underneath the crust is in a semi-molten state.
Answer: The intense heat in the earth's interior does not travel to the surface because rocks are bad conductors of heat. Therefore, the internal heat melts the rocks, keeping the asthenosphere in a semi-molten state.

(ii) Exogenic forces are also called destructive forces.
Answer: They are called destructive forces because they cause widespread destruction by continuously weathering and eroding existing landforms on the surface of the earth.

(iii) Residual mountains are also called mountains of denudation.
Answer: They are called mountains of denudation because they are formed entirely by the wearing down (denudation) of original highlands or plateaus through the prolonged action of winds, water, and snow.

(d) Draw a well labelled diagram to show the formation of block mountain.
Answer: (Students are expected to draw a diagram showing parallel faults with horizontal pulling/tensional forces, where the central block rises to form a Horst or Block Mountain, and adjacent valleys sink. See Fig. 5.5 in the textbook.)

2. (a) Describe the characteristics of two different types of plateaus.
Answer: 1. Intermontane Plateaus: They are the highest and most extensive plateaus on the globe, completely surrounded by hills and fold mountains on all sides (e.g., Tibetan Plateau).
2. Volcanic Plateaus: They are formed by numerous volcanic lava eruptions that slowly accumulate and build up over time to create a flat, elevated tableland (e.g., Columbian Plateau).

(b) Describe the characteristics of structural plains.
Answer: Structural plains are formed due to the vertical uplift or mild subsidence of land caused by diastrophic forces. They often emerge from submerged coastal lands under the ocean (resulting in vast lowlands with lakes) or form by mild subsidence followed by sedimentation.

(c) Give a reason for each of the following:
(i) There are different types of plains.
Answer: Plains are seldom formed by a single process; there are endless variations because they represent an imprint of various past and present processes, such as tectonic uplift, subsidence, erosion, and deposition.

(ii) Alluvial plains are regarded as the granaries of the world.
Answer: Alluvial plains are extremely fertile because rivers continuously deposit fresh soil and minerals (alluvium) onto them during floods, making them highly suitable for extensive agriculture.

(iii) The landforms on the surface of the earth are symbols of the energy of the earth.
Answer: Landforms are basically the result of the enormous heat generated inside the earth, which releases its internal energy through tectonic activity, earthquakes, and volcanic eruptions, permanently sculpturing the earth's crust.

(d) Explain the chief characteristics of depositional plains and their types.
Answer: Depositional plains are formed by the deposition of materials brought by various agents of transportation. The chief types are:
1. River Deposition Plains: Include alluvial plains, flood plains, and deltaic plains formed by rivers depositing silt.
2. Wind Deposition Plains: Formed in dry regions, characterized by irregular undulating surfaces with sand dunes (e.g., sandy deserts and loess plains).
3. Marine Deposition Plains: Found in coastal regions, formed by ocean waves and tides depositing sediments, or through human reclamation of land (polders).

V. Thinking Skills

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: (As a student in India, an example answer could be for Maharashtra) Our state is primarily located on the Deccan Plateau. It is a volcanic plateau formed millions of years ago by numerous volcanic eruptions and slow accumulation of basaltic lava. Over the years, external agents like rivers (such as Godavari and Krishna) and winds have constantly weathered and eroded this plateau, cutting deep valleys and leaving behind flat-topped residual hills.

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 enormous heat and pressure generated inside the earth remain trapped, the internal stress would build up continuously. Without safety mechanisms like volcanoes or minor tectonic shifts releasing this pressure gradually, the earth could experience catastrophic, planet-shattering explosions, completely destabilizing the crust. There would be no new landform creation—meaning no new mountains or volcanic plateaus would form to replenish weathered lands.

VI. Practical Work

1. Draw and colour different relief features on the surface of the earth.
Answer: (Students should use drawing materials to sketch mountains, plateaus, valleys, and plains, using standard geographical colours: brown for mountains, yellow/light brown for plateaus, and green for plains.)

2. On an outline map of the world show major fold mountains, plateaus and plains with the help of symbols.
Answer: (Students should take a blank world map and mark features like the Himalayas in Asia, Andes in South America, Rockies in North America, the Tibetan Plateau, and the Great Plains of the USA using appropriate map symbols.)