Chapter 2 Shaping of Earth’s Surface (NCERT) Questions with Answers

 

Chapter 2 Shaping of Earth’s Surface

(NCERT)

Questions & Answers

1. What is a landform?

Answer: A landform is a natural feature on the Earth's surface formed by weathering, erosion, deposition, and movement of the Earth's crust.

2. What is the difference between weathering and erosion?

Answer: Weathering breaks rocks into smaller pieces without moving them. Erosion carries the broken material from one place to another.

3. What are the sources of energy that are required to cause movements associated with the internal forces of the Earth?

Answer: Heat from the Earth's interior. This is the primary source. It causes convection currents in the mantle, which move tectonic plates and lead to earthquakes, volcanic eruptions, and mountain building.

4. Who proposed the theory of plate tectonics?

Answer: W.J. Morgan proposed the theory of plate tectonics.

5. Which ancient text contains a dedicated section on earthquakes, and who wrote it?

Answer: The Bṛihatsaṁhitā contains a dedicated section on earthquakes, written by Varāhamihira.

6. What are the three types of weathering?

Answer: Physical weathering Chemical weathering biological weathering

7. What are the three main layers of the Earth?

Answer: The crust, mantle, and core.

8. According to Varāhamihira, what signs could indicate an impending earthquake?

Answer: Changes in wind, rain, clouds, animal behaviour, and planetary alignments could signal them.

9. How does erosion affect farmers?

Answer: Erosion removes fertile topsoil, which can reduce crop production.

10. What is the lithosphere?

Answer: The rigid outer layer consisting of the crust and upper mantle.

11. What are the four elemental forces to which Varāhamihira attributed earthquakes?

Answer: The four elemental forces are Vāyu (wind), Agni (fire), Indra (heaven/thunder), and Varuṇa (water).

12. What is contouring?

Answer: Contouring involves digging trenches along the contour lines of a hillside to slow and hold rainwater and reduce soil erosion.

13. What is the asthenosphere?

Answer: A semi-molten layer beneath the lithosphere that allows tectonic plates to move.

14. How did Varāhamihira categorize four elemental forces in relation to earthquakes?

Answer: He linked each elemental force to specific constellations and regions.

15. What is terracing?

Answer: Terracing creates a series of level or gently sloping steps on a hillside to prevent soil erosion.

16. Name the three types of tectonic plates.

Answer: Continental, oceanic, and mixed plates.

17. What does this ancient approach to understanding earthquakes reflect about early Indian science?

Answer: It reflects an early attempt to blend observations with cosmological reasoning and physical phenomena in India.

18. Name the main agents of gradation.

Answer: Running water, glaciers, wind, waves and groundwater.

19. What causes tectonic plates to move?

Answer: Convection currents in the mantle caused by heat from the Earth's core.

20. How are meanders formed?

Answer: Rivers erode their outer banks and deposit sediments on their inner banks, gradually forming winding curves.

21. What are the three types of plate boundaries?

Answer: Convergent, divergent, and transform boundaries.

22. Why are deltas important?

Answer: Deltas have fertile soil and support agriculture, fishing, settlements and trade.

23. What shapes the Earth’s surface? What is plate tectonics?

Answer: Earth’s surface is shaped by internal forces such as plate tectonics, earthquakes and volcanoes, and external forces such as weathering, erosion and deposition. Plate tectonics is the theory that Earth’s lithosphere is divided into moving plates that interact to form mountains, oceans, earthquakes and volcanoes.

24. What forms when two continental plates collide?

Answer: Fold mountains such as the Himalaya.

25. What are the effects of plate movement?

Answer: Plate movement causes earthquakes, volcanic eruptions, mountain building, formation of ocean trenches and mid-ocean ridges, and the creation and breakup of continents.

26. What is weathering?

Answer: Weathering is the breaking down of rocks into smaller pieces. Does weathering involve movement?

27. Name the three types of weathering.

Answer: Physical, chemical and biological weathering.

28. What is erosion?

Answer: Erosion is the wearing away and movement of soil and rocks.

29. Name two agents of erosion.

Answer: Water and wind.

30. What is a meander?

Answer: A meander is a winding curve or bend in a river.

31. What is a delta?

Answer: A delta is a landform formed by deposition of sediments at a river's mouth.

32. What is a waterfall?

Answer: It is a river flowing over a steep drop or cliff.

33. What is a moraine?

Answer: A moraine is material deposited by a glacier.

34. What is a GLOF?

Answer: GLOF means Glacial Lake Outburst Flood.

35. What are dunes?

Answer: Dunes are hills or ridges of sand formed by wind.

36. What is a landslide?

Answer: It is the sudden movement of soil and rocks down a slope.

37. Name two coastal landforms.

Answer: Beaches and sea cliffs.

38. What is a sinkhole?

Answer: It is a depression formed when the ground collapses into an underground cavity.

39. Name two agents of gradation.

Answer: Running water and glacier

40. How do glaciers shape the land?

Answer: Glaciers scrape, erode and carry materials, forming landforms such as U-shaped valleys, cirques and fjords.

41. What is the Ring of Fire?

Answer: An area around the Pacific Ocean where most earthquakes and volcanoes occur.

42. How are landforms formed and how are they classified?

Answer: Landforms are formed by tectonic activity and by weathering, erosion and deposition. They are commonly classified as mountains, plateaus, plains, valleys, hills, deserts, coastal landforms and river landforms.

43. What causes dust storms?

Answer: Strong winds lift loose, dry soil and sand. Drought, low rainfall and sparse vegetation make dust storms more likely.

44. Name India’s only mud volcano?

Answer: India’s only mud volcano is in Baratang in the Andaman and Nicobar Islands.

 

Long Questions & Answers

1. What were earthquakes known as in early times, and what does the term mean?

Answer: In early times, earthquakes were known as ‘bhūkampa’, which means the shaking of the Earth.

2. Which ancient text contains a dedicated section on earthquakes, and who wrote it?

Answer: The Bṛihatsaṁhitā contains a dedicated section on earthquakes, written by Varāhamihira.

3. According to Varāhamihira, what signs could indicate an impending earthquake?

Answer: Changes in wind, rain, clouds, animal behaviour, and planetary alignments could signal them.

4. How are humans and other living beings connected to these landforms?

Answer: Humans, plants and animals depend on landforms for food, water, shelter, farming, transport and natural resources. Different landforms support different ecosystems, occupations and settlements.

5. What were earthquakes known as in early times, and what does the term mean?

Answer: In early times, earthquakes were known as ‘bhūkampa’, which means the shaking of the Earth.

6. How do disasters associated with different landforms impact human lives?

Answer: Disasters such as earthquakes, volcanic eruptions, landslides, floods and tsunamis can damage homes, infrastructure and farmland, cause injuries and loss of life, disrupt livelihoods and affect the environment.

7. Explain the different types of weathering.

Answer: Weathering is the process of breaking down rocks on the Earth's surface. It does not involve the movement of broken material. There are three main types: Physical weathering: Rocks break into smaller pieces due to temperature changes, frost or wind. Chemical weathering: Minerals in rocks change through reactions with water, air or acids. Biological weathering: Plants, animals and microorganisms break down rocks. For example, plant roots can grow into cracks and split rocks. Weathering helps shape the Earth's surface and contributes to soil formation.

8. Explain the causes of tectonic plate movement.

Answer: The movement of tectonic plates is caused by convection currents in the Earth's mantle. Heat from the Earth's core causes molten rock in the mantle to rise, while cooler material sinks. This continuous circulation creates convection currents that push and pull the tectonic plates in different directions. As the plates move, they interact at their boundaries, resulting in the formation of mountains, volcanoes, earthquakes, and other landforms.

9. How are deforestation and erosion associated with each other?

Answer: Deforestation removes trees and other vegetation that help hold soil together. Without vegetation, soil becomes loose and exposed to wind and water. This increases soil erosion. The chapter also notes that sparse vegetation caused by deforestation can leave land exposed and contribute to dust storms.

10. What precautionary measures will you take if you are staying in an earthquake-prone region?

Answer: Drop, cover, and hold on: “Drop down to the ground so the earthquake doesn't knock you down.” under a sturdy desk or table. Stay indoors: Avoid running outside or standing near glass windows and heavy objects. Protect in bed: Stay in bed and cover your head with a pillow if you are sleeping

11. Explain how landforms and natural processes affect human life.

Answer: Landforms influence human settlements, agriculture, trade, transport and culture. Rivers and fertile plains supported early agricultural societies and cities. Mountains acted as barriers and protectors, while mountain passes encouraged cultural exchange. Coasts and harbours supported trade and travel. Landforms also provide resources and tourism opportunities. At the same time, some landforms and processes can cause disasters such as landslides, avalanches, GLOFs and floods.

12. What are landforms? Explain how they are formed.

Answer: Landforms are natural features found on the Earth's surface. They are formed through processes such as weathering, erosion, deposition, and the movement of the Earth's crust. Examples include mountains, valleys, plateaus, plains, deserts, and coastal features. The movement of tectonic plates also plays an important role in creating many of these landforms through mountain building, volcanic eruptions, and earthquakes

13. Describe the three types of plate boundaries and the landforms they create.

Answer: There are three main types of plate boundaries: Convergent Boundary: Two plates move toward each other. Continental collisions form fold mountains like the Himalaya, while oceanic-continental collisions cause volcanic activity and earthquakes. Divergent Boundary: Two plates move apart, allowing magma to rise and create new crust. This forms mid-ocean ridges, such as the Mid-Atlantic Ridge. Transform Boundary: Two plates slide past one another without creating or destroying crust. This movement mainly causes earthquakes, such as along the San Andreas Fault. Each type of boundary contributes to the continuous reshaping of the Earth's surface.

14. Explain the importance of plate tectonics in shaping the Earth's surface.

Answer: Plate tectonics is one of the most important geological processes because it constantly reshapes the Earth's surface. The movement of tectonic plates forms mountains, valleys, volcanoes, ocean basins, and other landforms. It also explains the distribution of continents and oceans. Most earthquakes and volcanoes occur along plate boundaries, especially around the Pacific Ocean, known as the Ring of Fire. Thus, plate tectonics helps us understand many natural processes occurring on Earth.

15. Explain the difference between the lithosphere and the asthenosphere.

Answer: The lithosphere is the rigid outer layer of the Earth made up of the crust and the uppermost part of the mantle. It is broken into tectonic plates. The asthenosphere lies beneath the lithosphere and is a hot, semi-molten layer of partially melted rock. Its soft and mobile nature allows the tectonic plates above it to move slowly. This movement is responsible for many geological activities on Earth.

16. Why do earthquakes and volcanoes occur mainly along plate boundaries?

Answer: Earthquakes and volcanoes occur mainly along plate boundaries because this is where tectonic plates interact. At convergent boundaries, plates collide, creating intense pressure, earthquakes, and volcanic eruptions. At divergent boundaries, magma rises through gaps to form new crust and volcanoes. At transform boundaries, plates slide past one another, causing earthquakes due to friction. Therefore, plate boundaries are the most active geological zones on Earth.

17. Explain how rivers form different landforms.

Answer: Rivers shape land through erosion, transportation and deposition. In the upper course, rivers form V-shaped valleys, waterfalls and rapids. In the middle course, rivers form meanders, oxbow lakes and floodplains. In the lower course, rivers deposit sediments and form deltas, levees and alluvial fans. These landforms are important for agriculture, settlements and ecosystems.

18. Explain the different landforms formed by coastal erosion.

Answer: Waves, tides and currents wear away coastal land. This process is called coastal erosion. It forms: Cliffs – steep rock faces formed when waves wear away the coast. Wave-cut platforms – flat areas left as cliffs retreat. Caves – formed when waves erode weak parts of rocks. Arches – formed when caves meet through a headland. Stacks – isolated rock pillars left after arches collapse. These landforms also influence tourism and the need for coastal protection.

19. Why and where do earthquakes occur frequently? Is it possible to predict earthquakes?

Answer: Ring of Fire and Boundaries: Most quakes happen along active edges where these plates meet, such as the Pacific Ring of Fire or major fault systems like the San Andreas Fault and Alpine-Himalayan belt According to the Survey, scientists cannot predict the exact time, date, and magnitude of any single upcoming. Instead of prediction, modern networks offer brief early warning alerts lasting from seconds to minutes after a quake starts to help people take cover

20. What are tectonic plates? Describe their types with examples.

Answer: Tectonic plates are huge slabs of solid rock that make up the Earth's lithosphere. They move slowly, usually a few centimetres each year. There are three types of tectonic plates: Continental plates, which carry continents. Oceanic plates, which carry ocean floors. Mixed plates, which contain both continental and oceanic crust. Some major tectonic plates include the Pacific Plate, Eurasian Plate, African Plate, North American Plate, South American Plate, Indo-Australian Plate, and Antarctic Plate. Their movement shapes the Earth's surface and causes many geological events.

21. Explain the causes of landslides.

Answer: Landslides occur when slopes become unstable. Heavy rainfall increases the weight of soil and reduces friction. Earthquakes and volcanic eruptions can also trigger landslides. Steep slopes and loose rocks increase the risk. Human activities such as deforestation, mining, road construction and unplanned construction can also make slopes unstable. Poor drainage and improper land use may further increase the risk.

22. Write a detailed note on the significance of studying plate tectonics and landforms.

Answer: Studying plate tectonics and landforms helps us understand how the Earth's surface changes over time. Plate tectonics explains the movement of tectonic plates and the formation of mountains, volcanoes, valleys, and ocean basins. It also helps explain natural events such as earthquakes and volcanic eruptions. Landforms, created by weathering, erosion, deposition, and crustal movement, reveal the dynamic nature of the Earth. This knowledge is valuable for understanding natural hazards, Earth's history, and the development of continents and oceans.

23. Describe the structure of the Earth.

Answer: The Earth has three main layers: the crust, mantle, and core. The crust is the thin outermost layer where humans live. Below it lies the mantle, which is thick and hot. The upper part of the mantle and the crust together form the lithosphere, which is divided into tectonic plates. Beneath the lithosphere is the semi-molten asthenosphere that allows these plates to move. The core consists of two parts: the outer core, which is a liquid layer mainly made of iron and nickel, and the inner core, which is a solid, extremely hot, and dense metal ball.

24. Relate various physiographic divisions of India with various endogenic forces responsible for their origin.

Answer: India's major physiographic divisions—the Himalayas, the Peninsular Plateau, and the Northern Plains—are directly linked to internal or endogenic forces like plate collision, volcanic activity, and tectonic subsidence.

 

Himalayan Mountains:

 Convergent Plate Movement: Formed by the collision of the Indian Plate and the Eurasian Plate. Folding and Uplift: “When these two continental plates collided, the land was pushed upward, forming these young fold mountains,”

 Peninsular Plateau: Developed through ancient volcanic activity and stable block faulting. Ancient Landmass: “Plateaus, like the Deccan Plateau, developed through volcanic activity,” explaining its hard igneous rock base

Northern Plains: Subsidence and Faulting: Formed over a large structural depression or basin created in front of the advancing Himalayas. Tectonic Sinking: “The base was created by the sinking (subsidence) of the land due to faulting,” which was later filled by river sediments