Shaping of the Earth’s Surface Class 9 Question Answer SST Chapter 2

Class 9 SST Chapter 2 Shaping of the Earth’s Surface Question Answer

The Big Questions (Page No. 13)

Question 1.
What shapes the Earth’s surface?
Answer:
The Earth’s surface is shaped by both internal (endogenic) forces and external (exogenic) forces. Internal forces such as tectonic movements, earthquakes and volcanic eruptions create landforms like mountains and plateaus. External forces such as weathering, erosion and deposition by rivers, wind, glaciers and waves continuously modify and reshape these landforms.

Question 2.
What is plate tectonics? What are the effects of plate movement?
Answer:
Plate tectonics is the theory that the Earth’s lithosphere is divided into several large and small tectonic plates that move slowly over the semi-molten asthenosphere. The movement of these plates leads to the formation of mountains, earthquakes, volcanoes, ocean trenches and rift valleys. It also causes earthquakes and influences the distribution of continents and oceans.

Question 3.
How are landforms formed and how are they classified?
Answer:
Landforms are formed by the combined action of internal and external forces. Internal forces create landforms through processes such as folding, faulting and volcanism, while external forces shape them through weathering, erosion and deposition. Landforms are broadly classified into mountains, plateaus and plains, along with other features such as valleys, deserts, deltas, beaches and coastal landforms.

Question 4.
How are humans and other living beings connected to these landforms?
Answer:
Landforms influence climate, soil, water availability, yegetation, agriculture, settlements, transportation and economic activities. Different plants and animals adapt to specific landforms and environments. Humans depend on landforms for resources, livelihood, habitation and development, making them closely connected to the physical landscape.

Question 5.
How do disasters associated with different landforms impact human lives?
Answer:
Disasters such as earthquakes, volcanic eruptions, landslides, avalanches, Glacial Lake Outburst Floods (GLOFs), floods and dust storms can cause loss of life and property, damage infrastructure, disrupt transportation and communication, affect agriculture and harm the environment. Understanding these hazards helps people prepare for disasters and reduce their impacts.

Let’s Map (Page-16)

Question 1.
Pick any two plates from the map above and complete the table given below.
Answer:

Name of the Plate	Continents Present	Ocean Present
Indo-Australian Plate	Asia, Australia	Indian Ocean
South American Plate	South America	Atlantic Ocean

Let’s Explore (Page-16)

Question 1.
Examine the plate map with the earthquake and volcano map. What correlation do you observe?


Answer:
Most earthquakes and volcanoes are concentrated along the boundaries of tectonic plates. Areas where plates collide, move apart, or slide past one another experience frequent earthquakes and volcanic eruptions. This shows that plate movements are closely related to the occurrence of earthquakes and volcanoes.
(Answers may vary)

Let’s Explore (Page-17)

Question 1.
Observe the map showing the distribution of earthquakes and volcanoes. Can you identify which continents and countries are located around the Ring of Fire? (For Map refer the Map showing the distribution of earthquakes and volcanoes in above Question)
Answer:
The Ring of Fire surrounds the Pacific Ocean and includes parts of Asia, North America, South America and Australia. Countries such as Japan, Indonesia, the Philippines, New Zealand, the United States, Chile and Peru lie within this zone.

Let’s Explore (Page-17)

Question 1.
Does India have a risk of earthquakes? Which region is more vulnerable to earthquakes? Why do you think human lives are at risk?
Answer:
Yes, India has a significant risk of earthquakes because it lies near active tectonic plate boundaries. The Himalayan region, including Jammu and Kashmir, Himachal Pradesh, Uttarakhand and the North-Eastern states, is particularly vulnerable to earthquakes. These regions experience frequent seismic activity due to the continuous collision of the Indian Plate with the Eurasian Plate. Human lives are at risk because earthquakes can cause the collapse of buildings, bridges and other infrastructure. Landslides, ground shaking and disruption of essential services further increase the danger. In densely populated areas, unplanned construction and inadequate safety measures can lead to greater loss of life and property during earthquakes.

Let’s Explore (Page-18)

Question 1.
Look carefully at this photograph and answer the following questions.

(a) What do you think caused this situation?
Answer:
This situation was caused by a volcanic eruption. During an eruption, ash, gases and molten materials (magma) are expelled from inside the Earth and spread over nearby areas, affecting people, vegetation and settlements.

(b) What could that grey powder be?
Answer:
The grey powder visible in the photograph is volcanic ash. It consists of fine particles of rock, minerals and volcanic gases released during a volcanic eruption and deposited over the surrounding area.

(c) What does it tell us about the Earth’s internal forces?
Answer:
The photograph shows that powerful internal (endogenic) forces operate beneath the Earth’s surface. These forces can force magma, gases and ash upward, causing volcanic eruptions and significantly altering the Earth’s surface.

Let’s Explore (Page-21)

Question 1.
Observe the photographs and note the types of erosion. How are farmers affected by erosion due to water and wind?

Answer:
(a) Water erosion (left photograph) and (b) Wind erosion (right photograph)

• Water erosion removes the fertile topsoil from agricultural fields through rainfall and flowing water.
• Wind erosion blows away fine soil particles, especially in dry and sandy regions.
• The loss of topsoil reduces soil fertility and removes essential nutrients needed for plant growth.
• As a result, crop yields decrease and agricultural productivity declines.
• This affects farmers’ income and livelihoods and may increase the cost of farming.

Let’s Explore (Page-25)

Question 1.
Have you heard about the Sundarbans delta? Try and explore its uniqueness and find out why it is popular with tourists.

Answer:
The Sundarbans Delta is the largest delta in the world, formed by the rivers Ganga, Brahmaputra and Meghna. It is spread across India and Bangladesh and is famous for its extensive mangrove forests, which are among the largest in the world. The region is home to the Royal Bengal Tiger and many other species of plants and animals. Its unique network of rivers, creeks and islands support a rich and diverse ecosystem. The Sundarbans is a UNESCO World Heritage Site and is popular with tourists because of its natural beauty, wildlife, boat safaris and opportunities to observe rare species in their natural habitat. It attracts nature lovers, wildlife enthusiasts and adventure seekers from around the world.

Think About It (Page-29)

Question 1.
A devastating flood struck the Chamoli district in Uttarakhand in February 2021. Can you find out the reasons that led to the sudden and unexpected flood?

Answer:

1. The Chamoli disaster occurred on 7 February 2021 in the high Himalayan region of Uttarakhand.
2. A large mass of rock and ice broke away from a mountain slope near the Rishiganga valley.
3. The sudden collapse generated a powerful flow of water, ice, rocks and debris down the valley.
4. This triggered flash floods in the Rishiganga and Dhauliganga rivers.
5. The flood caused severe damage to hydropower projects, bridges, roads and communication networks.
6. The fragile Himalayan environment, steep slopes and unstable glaciers increased the intensity of the disaster.
7. Scientists have suggested that rising temperatures and climate change may increase the risk of such events, although the immediate cause was the rock and ice avalanche.

Let’s Explore (Page-32)

Question 1.
Complete the exercises given at the end of each type of disaster with the help of newspapers, atlases, and books. Make a list of disaster-prone areas from India and the world and enlist mitigation measures quoting recent examples.
Answer:

Type of Disaster	Disaster-Prone Areas (India)	Disaster-Prone Areas (World)	Mitigation Measures	Recent Example
Earthquakes	Himalayan region, North-Eastern states, Jammu and Kashmir, Gujarat	Japan, Indonesia, Turkey, California (USA), Chile	Earthquake-resistant buildings, early warning systems, public awareness, disaster preparedness	Turkey-Syria Earthquake (2023)
Landslides	Himalayan region, Western Ghats, North-Eastern states, Nilgiri Hills	Nepal, Andes Moun­tains, Japan, Philip­pines	Afforestation, proper drain­age, slope stabilisation, restricting construction on steep slopes	Wayanad Land­slides, Kerala (2024)
Avalanches	Jammu and Kashmir, Ladakh, Himachal Pradesh, Uttarakhand	Alps (Europe), Rocky Mountains (North America), Himalayas (Nepal)	Avalanche forecasting, snow barriers, controlled blasting, restricting activi­ties in high-risk zones	Avalanches in Chamoli, Uttara­khand
GLOFs (Glacial Lake Outburst Floods)	Sikkim, Uttarakhand, Himachal Pradesh, Ladakh	Nepal, Bhutan, Tibet (China), Peru	Monitoring glacial lakes, early warning systems, con­trolled drainage, disaster preparedness plans	South Lhonak Lake GLOF, Sikkim (2023)
Dust Storms	Rajasthan, Gujarat, Haryana, Western Ut­tar Pradesh	Sahara Desert (Africa), Arabian Peninsula, Central Asia, Australia	Afforestation, shelter belts, soil conservation, sustain­able farming practices	Frequent dust storms in Rajas­than and North­Western India
Floods	Assam, Bihar, Uttar Pradesh, West Bengal, Kerala	Bangladesh, China, Pakistan, Netherlands	Embankments, flood fore­casting, improved drainage, watershed management	Assam Floods (2024)
Cyclones	Odisha, Andhra Pradesh, West Bengal, Tamil Nadu, Gujarat	Philippines, Japan, USA, Bangladesh	Early warning systems, cyclone shelters, coastal embankments, evacuation plans	Cyclone Remal (2024)

Question 2.
Observe the landforms around your school or residence and try to identify which agent may have created them.
Answer:
The landforms around us are shaped by different natural agents of erosion and deposition. By observing local features, we can identify the responsible agent:

Running Water (Rivers): Creates V-shaped valleys, floodplains, and meanders through erosion and deposition.

Wind: Forms sand dunes and rock features in dry, sandy regions by transporting and depositing sand.

Waves and Currents: Shape coastal landforms such as beaches, sea cliffs, and sea caves.

Glaciers: Create U-shaped valleys and moraines in mountainous areas through the movement of ice. Underground Water: Forms sinkholes and limestone caves by dissolving soluble rocks.

Thus, the landforms around a place reflect the dominant natural agent that has shaped the landscape over time.

Landslides (Page-33)

Landslides
Landslides are caused by a combination of natural and human factors that make slopes unstable. Heavy and continuous rainfall is one of the main natural causes, as water seeps into the soil and rocks, increasing their weight and reducing friction. Earthquakes and volcanic eruptions can also trigger landslides by shaking the ground and weakening slopes. Steep slopes and the presence of loose or weathered rocks further increase the risk. Human activities, such as deforestation, mining, road construction and unplanned construction on hillsides disturb the natural balance of slopes. Poor drainage systems and improper land use also contribute to landslides by allowing excess water to accumulate, leading to sudden slope failure.

Answer:
Prone Areas

• Himalayan region
• Western Ghats
• North-Eastern states
• Nilgiri Hills

Mitigation Measures

• Afforestation
• Proper drainage systems
• Restrict construction on steep slopes
• Slope stabilisation and retaining walls

Recent Example

• Wayanad Landslides, Kerala (2024)

Avalanches (Page-34)

Avalanches
Avalanches are caused by the sudden instability of snow on steep mountain slopes. Heavy snowfall within a short period adds extra weight to the snowpack, making it unstable, especially when it rests on weak or loosely bonded layers of snow. A sudden rise in temperature can cause partial melting, reducing the friction that holds the snow together. Strong winds may also pile up snow unevenly, creating fragile layers. Natural disturbances, such as earthquakes and vibrations, as well as human activities like skiing, trekking, or construction in mountainous areas, can trigger avalanches by disturbing the balance of the snow-covered slopes.

Answer:
Prone Areas

• Jammu and Kashmir
• Ladakh
• Himachal Pradesh
• Uttarakhand

Mitigation Measures

• Avalanche forecasting and early warning systems
• Snow barriers and protective fences
• Controlled blasting to release unstable snow
• Restricting activities and construction in high-risk zones

Recent Example

• Avalanches in Chamoli (Uttarakhand)

GLOFs (Glacial Lake Outburst Floods) (Page-35)

GLOFs
Glacial Lake Outburst Floods (GLOFs) are caused by the sudden release of large volumes of water from glacial lakes due to natural and climatic factors. Rapid melting of glaciers because of rising temperatures increases the size and water level of glacial lakes, putting pressure on their natural dams made of ice or loose moraines. Heavy rainfall or intense snowfall can add excess water to these lakes. Earthquakes, avalanches, or landslides may strike the lake or weaken the dam, leading to its sudden collapse. As a result, the stored water is released abruptly, causing destructive floods in downstream areas.

Answer:
Prone Areas

• Sikkim
• Uttarakhand
• Himachal Pradesh
• Ladakh
• Arunachal Pradesh Mitigation Measures
• Monitoring glacial lakes
• Early warning systems
• Controlled drainage of lakes
• Disaster preparedness plans

Recent Example

• South Lhonak Lake GLOF, Sikkim (2023)

Dust Storms (Page-36)

Dust Storms
Dust storms are caused by strong winds lifting large amounts of loose, dry soil and sand into the air. Prolonged drought and low rainfall dry out the soil, making it easier for wind to pick up the fine particles. Dust storms are common in desert and semi-arid regions where the soil is loose and dry. Sparse vegetation cover, often due to deforestation, overgrazing, or poor farming practices, also leaves the land exposed. Climate change and extreme weather conditions can further increase the frequency and intensity of dust storms.

Answer:
Prone Areas

• Rajasthan (Thar Desert)
• Gujarat
• Haryana
• Western Uttar Pradesh Mitigation Measures
• Afforestation and increasing vegetation cover
• Planting shelter belts and windbreaks
• Adopting sustainable farming practices
• Soil conservation measures and proper land manage-ment

Recent Example

• Frequent dust storms in Rajasthan and North-Western India during the summer months

Questions and Activities (Page No. 37-38)

Question 1.
What are the sources of energy that are required to cause movements associated with the internal forces of the Earth?
Answer:

1. The main source of energy is the heat generated inside the Earth.
2. This heat comes from the Earth’s formation and the radioactive decay of minerals.
3. Internal heat creates convection currents in the mantle.
4. These currents cause tectonic plates to move slowly over the asthenosphere.
5. Such movements generate earthquakes, volcanic eruptions, folding and faulting.
6. Therefore, internal heat energy is responsible for most endogenic processes shaping the Earth’s surface.

Question 2.
Relate various physiographic divisions you have studied in the earlier grades with various endogenic forces responsible for their origin.
Answer:

1. The Himalayan Mountains were formed due to folding caused by the collision of the Indian Plate with. the Eurasian Plate.
2. Rift valleys such as the Narmada Valley were formed’ due to faulting, where blocks of the Earth’s crust moved along fractures.
3. The Deccan Plateau was formed through extensive volcanic activity and lava deposition.
4. Many mountain ranges around the world have developed due to compressional forces acting on the Earth’s crust.
5. Plateaus are often created through upliftment or volcanic eruptions.
6. Ocean basins and trenches are also products of tectonic activity beneath the Earth’s surface.
7. Thus, different physiographic divisions are directly linked to various endogenic forces such as folding, faulting, volcanism and tectonic movements.

Question 3.
Why and where do earthquakes occur frequently? Is it possible to predict earthquakes?
Answer:
Earthquakes occur when stress accumulated within the Earth’s crust is suddenly released. This release of energy generates seismic waves that cause the ground to shake. Most earthquakes occur along tectonic plate boundaries where plates collide, separate or slide past one another. Regions such as the Pacific Ring of Fire, the Himalayan belt, Japan, Indonesia, Turkey and parts of California experience frequent earthquakes because of active tectonic movements.

Scientists can identify earthquake-prone regions and monitor seismic activity with the help of modern instruments and geological studies. They can estimate the likelihood of earthquakes occurring in certain areas based on past records and tectonic conditions. However, it is not yet possible to predict the exact time, location and magnitude of an earthquake accurately. Therefore, disaster preparedness, public awareness and earthquake- resistant construction remain the most effective measures for reducing the impact of earthquakes.

Question 4.
“Plate movements are responsible for the distribution of earthquakes and volcanoes”. Explain.
Answer:

1. The Earth’s lithosphere is divided into several tectonic plates that move continuously over the asthenosphere.
2. Most earthquakes and volcanoes are concentrated near plate boundaries where these plates interact.
3. At convergent boundaries, colliding plates generate strong earthquakes and volcanic activity.
4. At divergent boundaries, plates move apart, allowing magma to rise and create new crust and volcanoes.
5. At transform boundaries, plates slide past one another, causing earthquakes due to friction and stress release.
6. The Pacific Ring of Fire is the best example of a region where plate movements produce frequent earthquakes and volcanic eruptions.
7. Therefore, the global distribution of earthquakes and volcanoes is closely linked to tectonic plate movements.

Question 5.
Draw and label a diagram of a meander and a delta.
Answer:

Question 6.
How are deforestation and erosion associated with each other? Explain.
Answer:

1. Trees and plants help bind the soil with their roots.
2. Deforestation removes vegetation cover and exposes the soil.
3. Exposed soil is easily carried away by wind and flowing water.
4. The loss of fertile topsoil reduces agricultural productivity.
5. Soil erosion may also increase the risk of landslides and floods.
6. Therefore, deforestation directly accelerates erosion and land degradation.

Question 7.
Develop a plan to protect the land in your local area from erosion.
Answer:

1. Plant more trees and grass to hold the soil firmly.
2. Promote afforestation and prevent unnecessary cutting of trees.
3. Construct contour trenches and bunds on sloping land.
4. Improve drainage systems to reduce waterlogging and runoff.
5. Encourage farmers to adopt soil conservation techniques.
6. Conduct awareness programmes about the harmful effects of soil erosion.
7. Regular monitoring should be carried out in erosion-prone areas.

Question 8.
Which disasters do you think you might experience in your region? Discuss a mitigation plan in your classroom.
Answer:
The disasters that may occur in a region depend on its geographical location and climatic conditions. Common disasters include floods, earthquakes, landslides, droughts, ayclones and heatwaves. To reduce their impact, effective mitigation measures should be adopted. Early warning systems should be strengthened to provide timely alerts to people. Emergency kits and evacuation plans should be priepared in advance. Regular awareness programmes and mock drills should be organised in schools and communities. Buildings should be constructed according to safety standards and local authorities should ensure proper disaster preparedness. Community participation is also essential for effective disaster management and reducing the loss of life and property.

Question 9.
Prepare a model of landforms created by underground water.
Answer:

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

• Buildings should be constructed according to earthquake-resistant designs and safety standards.
• Heavy furniture, cupboards and appliances should be securely fixed to walls.
• Emergency supplies such as drinking water, food, a first- aid kit and a torch should be kept ready.
• During an earthquake, one should follow the “Drop, Cover and Hold” procedure.
• Open and safe areas should be identified for evacuation after the shaking stops.
• Regular earthquake preparedness drills and awareness programmes should be conducted.
• Emergency contact numbers and disaster helpline numbers should be kept easily accessible.
• Elevators should not be used during or immediately after an earthquake.

Question 11.
Prepare a map showing landform-associated disasters that happened in the current calendar year.
Answer:

Question 12.
Create a poster showing landforms that are considered sacred or important in your region and add folk stories associated with them.
Answer:

(Answers may vary)

Question 13.
Document a case of a disaster that hit your region in the past, highlighting its effects on various human activities.
Answer:

1. Students may select any disaster that affected their region, such as a flood, earthquake, landslide, cyclone or drought:
2. The date, location and causes of the disaster should be mentioned.
3. The disaster may have caused loss.
4. Agricultural activities could have been affected due to damage to crops and farmland.
5. Transport and communication networks may have been disrupted.
6. Schools, hospitals and businesses might have remained closed for several days.
7. Economic losses and environmental damage may also have occurred.
8. The report should conclude with lessons learned and measures taken to reduce future risks.

Case Study: Cyclone Fani (Odisha, 2019)
Cyclone Fani was a severe tropical cyclone that struck the coast of Odisha on 3 May 2019. The cyclone made landfall near Puri with very high wind speeds and heavy rainfall. It was caused by the formation of a low-pressure system over the Bay of Bengal that intensified into a powerful cyclone.

The cyclone caused extensive damage to houses, electric poles, roads communication networks. Many trees were uprooted thousands of people were evacuated to safer places. Agricultural activities were severely affected as crops and farmlands were damaged by strong winds and flooding.
Transportation services, including road, rail air transport, were disrupted for several days. Schools, colleges, hospitals businesses remained closed in many affected areas. Power supply and communication services were also interrupted.

The disaster resulted in significant economic losses and environmental damage. However, timely evacuation and effective disaster management by the government helped reduce the loss of human lives. This event highlighted the importance of early warning systems, disaster preparedness, cyclone shelters public awareness. Since then, efforts have been made to strengthen disaster management measures and improve resilience against future cyclones.
(Answers may vary)

Question 14.
Translate the given poster on landslide in to your native language and display it in your home.

Answer:
Carry out this activity yourself to explore and understand the concept better. (Do it yourself)

Question 15.
Divide the class into three groups. Each group will work on one project (water, wind and glacier). The project should highlight the causes, impact on human life and the environment and mitigation measures.
Answer:
The class should be divided into different groups and each group should be assigned one agent of gradation such as water, wind or glacier. Each group should identify and study the major landforms created by its assigned agent. They should explain how these agents shape the Earth’s surface through the processes of erosion, transportation and deposition. The groups should also describe how these landforms influence human activities such as agriculture, transportation, tourism and settlement. In addition, they should discuss disasters associated with each agent, such as floods caused by water, dust storms caused by wind and glacial lake outburst floods caused by glaciers. The impact of these disasters on human life, property, agriculture and infrastructure should be analysed. Finally, suitable mitigation measures should be suggested and the findings should be presented through charts, maps, models or PowerPoint presentations.

Group 1 – Water

• Landforms: Valleys, waterfalls, meanders, floodplains, deltas.
• Impact on Human Life and Environment: Supports agriculture, settlements, transportation and tourism.
• Associated Disasters: Floods and riverbank erosion.
• Mitigation Measures: Embankments, flood forecasting, watershed management and afforestation.

Group 2 – Wind

• Landforms: Sand dunes, mushroom rocks and loess deposits.
• Impact on Human Life and Environment: Influences agriculture, settlements and transportation in dry regions.
• Associated Disasters: Dust storms and desertification.
• Mitigation Measures: Afforestation, shelter belts and soil conservation.

Group 3 – Glacier

• Landforms: U-shaped valleys, cirques, moraines and glacial lakes.
• Impact on Human Life and Environment: Provides freshwater, supports tourism and hydropower generation.
• Associated Disasters: Avalanches and Glacial Lake Outburst Floods (GLOFs).
• Mitigation Measures: Monitoring glacial lakes, early warning systems and disaster preparedness plans.

Conclusion:
Water, wind and glaciers continuously shape the Earth’s surface through erosion, transportation and deposition. While they create important landforms, they can also cause disasters. Proper conservation and disaster management measures help reduce their impact.

Shaping of the Earth’s Surface Class 9 Extra Questions and Answers

Shaping of the Earth’s Surface Class 9 Very Short Question Answer

Question 1.
Why do earthquakes occur more frequently along transform plate boundaries than in the middle of tectonic plates?
Answer:

1. Transform boundaries involve plates sliding past each other, creating friction.
2. Stress builds up along faults and is suddenly released, causing earthquakes.

Question 2.
Who proposed the theory of plate tectonics? What does this theory explain?
Answer:
The theory of plate tectonics was proposed by W. J. Morgan. It explains the movement of the Earth’s crust and how this movement results in the formation of mountains, earthquakes, and volcanoes.

Question 3.
Define gradation and name any two agents responsible for it.
Answer:
Gradation is the process of levelling the Earth’s surface through erosion (degradation) and deposition (aggradation).
The two agents of gradation are: Running water (rivers) and wind.

Question 4.
What are natural levees and how are they formed?
Answer:
Natural levees are raised embankments along river banks.
They are formed when floodwaters overflow the river and heavier sediments are deposited close to the channel. Thus, repeated deposition gradually raises the banks.

Question 5.
Why do earthquakes occurring under the sea sometimes lead to more destruction than those occurring on land?
Answer:

1. Undersea earthquakes can displace large volumes of water, generating tsunamis.
2. The waves caused by these tsunamis travel long distances and cause widespread coastal destruction in addition to ground shaking.

Question 6.
“A village located in a mountainous region experienced heavy snowfall followed by a sudden rise in temperature. A few days later, a massive mass of snow rushed down the slope, burying roads and damaging houses”. Explain two factors that triggered this disaster.
Answer:

1. Heavy snowfall accumulated large amounts of snow on slopes.
2. Sudden rise in temperature weakened the snow layers, causing them to slide downhill as avalanches.

Shaping of the Earth’s Surface Class 9 Short Question Answer

Question 1.
Explain why the Himalayas are still rising today.
Answer:

1. The Indian plate is still moving northwards.
2. If continues to collide with the Eurasian plate.
3. Ongoing compression causes uplift and frequent earthquakes in the region.

Question 2.
Why is the asthenosphere important for plate tectonics even though it is not visible from the Earth’s surface?
Answer:

1. It is a semi-fluid layer that allows tectonic plates to move.
2. Convection currents in this layer drive plate movement.
3. Without it, the rigid lithospheric plates would not be able to drift.

Question 3.
A town located in the upper course of a river is experiencing deep valleys and fast-flowing water, while another town in the lower course has wide flat plains. Explain the geographical reasons for this difference.
Answer:

1. In the upper course, the river flows over steep slopes, causing strong vertical erosion.
2. This results in the formation of V-shaped valleys and deep channels.
3. In the lower course, the slope becomes gentle and the river velocity decreases.
4. The river deposits sediments, forming wide flood-plains and levees.

Question 4.
Coastal engineers plan to construct buildings near a sea cliff. Based on coastal geomorphic processes, explain why this may be risky.
Answer:

1. Sea cliffs are formed due to continuous wave erosion at the base.
2. Waves gradually weaken the rock structure and create sea caves.
3. This leads to collapse and retreat of cliffs over time.
4. Therefore, construction near cliffs is unsafe due to ongoing coastal erosion.

Question 5.
A town located near steep Himalayan slopes has recently experienced heavy rainfall. Explain why this region is highly vulnerable to landslides.
Answer:

1. The Himalayas have steep and unstable slopes.
2. Heavy rainfall loosens soil and weakens slope stability.
3. The region is geologically young and fragile, making landslides more frequent.

Question 6.
Explain why L-waves cause more damage than P-waves and S-waves during an earthquake.
Answer:

1. L-waves travel along the Earth’s surface.
2. They have larger amplitude and longer duration.
3. Since human settlements and structures are located on the surface, these waves cause maximum destruction.

Shaping of the Earth’s Surface Class 9 Long Question Answer

Question 1.
Analyse how plate tectonics helps in disaster management and urban planning.
Answer:

1. Identifies earthquake-prone regions along plate boundaries.
2. Helps governments create seismic hazard maps.
3. Guides the construction of earthquake-resistant buildings.
4. Assists in planning cities away from highly active fault zones.
5. Helps in early warning systems for tsunamis in subduction zones.

Question 2.
Evaluate the role of plate tectonics in shaping both physical geography and human activities.
Answer:

1. Forms mountains, plains and ocean basins that influence settlement patterns.
2. Controls distribution of natural resources such as minerals and fossil fuels.
3. Causes natural hazards that affect human life and infrastructure.
4. Influences climate through mountain building and ocean current changes.
5. Determines long-term evolution of continents and ecosystems.

Question 3.
Explain the role of weathering and erosion in shaping the Earth’s surface.
Answer:

1. Weathering and erosion are major geomorphic ’’processes responsible for shaping landforms.
2. Weathering breaks down rocks in-situ through physical, chemical and biological processes.
3. Erosion removes and transports weathered materials by agents like rivers, wind and glaciers.
4. These processes reduce relief differences by lowering highlands and filling lowlands.
5. Deposition of sediments leads to the formation of fertile plains, deltas and other landforms.
6. Together, weathering and erosion continuously modify and reshape the Earth’s landscape.
   (Any Five Points)

Question 4.
A region composed mainly of limestone shows caves, sinkholes and underground drainage instead of surface rivers. Explain the processes responsible for this landscape and identify the type of topography.
Answer:

1. Limestone is soluble in slightly acidic water containing carbon dioxide.
2. Underground water dissolves limestone through carbonation.
3. This forms caves beneath the surface.
4. Collapse of cave roofs leads to formation of sinkholes.
5. The region develops karst topography, characterised by underground drainage and depositional features like stalactites and stalagmites.

Question 5.
Analyse why the Himalayan region is highly vulnerable to disasters such as landslides, avalanches and Glacial Lake Outburst Floods (GLOFs).
Answer:

1. The Himalayas are geologically young and structurally unstable.
2. The region has steep slopes which increase the gravitational movement of debris.
3. Heavy rainfall weakens soil and triggers frequent landslides.
4. Heavy snowfall and sudden temperature rise lead to avalanches.
5. Numerous glaciers in the Himalayas form glacial lakes behind weak moraine dams.
6. Earthquakes in this tectonically active zone can trigger both landslides and GLOFs.
7. Climate change is increasing glacier melting, raising the risk of lake outburst floods. (Any Five Points)

Question 6.
Evaluate the role of human activities in increasing the frequency and severity of disasters such as landslides and dust storms.
Answer:

1. Deforestation removes vegetation that binds soil, making slopes unstable and prone to landslides.
2. Construction and road building in hilly regions disturb natural slope stability.
3. Mining activities weaken rock structure and increase the chances of slope failure.
4. Overgrazing in arid regions reduces vegetation cover and exposes loose soil.
5. Loose and dry soil is easily lifted by strong winds, increasing the frequency of dust storms.
6. Human activities therefore intensify natural geomorphic processes and increase disaster risk.

Shaping of the Earth’s Surface Class 9 Competency Based Questions

Question 1.
Define plate tectonics. Name any two types of plate boundaries and briefly state how they differ.
Answer:

1. Plate tectonics is the theory that explains the movement of lithospheric plates over the asthenosphere.
2. Convergent boundary: Plates move towards each » other, leading to subduction or mountain formation.
3. Divergent boundary: Plates move away from each other, forming new crust at mid-ocean ridges.

Question 2.
Explain the structure of the Earth’s interior and mention one characteristic of each layer.
Answer:

1. Crust: Outermost thin layer; continental crust is thicker than oceanic crust.
2. Mantle: Thick middle layer; contains semi-molten asthenosphere enabling plate movement.
3. Core: Innermost layer; composed mainly of nickel and iron (NiFe).

Question 3.
Define weathering and erosion. Mention one key difference between them.
Answer:

1. Weathering is the in-situ breakdown of rocks due to atmospheric factors.
2. Erosion is the removal and transportation of weathered materials by natural agents.

Difference: Weathering occurs at the same place, while erosion involves movement.

Question 4.
What are seismic waves? Name the three types of seismic waves and state one characteristic of each.
Answer:

1. Seismic waves are energy waves generated by earthquakes that travel through the Earth.
2. P-waves (Primary waves): Fastest waves; travel through solids, liquids and gases.
3. S-waves (Secondary waves): Travel only through solids and are slower than P-waves.
4. L-waves (Surface waves): Travel along the Earth’s surface and cause maximum damage.

Question 5.
Explain why earthquakes are frequent in the Himalayan region using the concept of plate tectonics.
Answer:

1. The Indian Plate is moving northwards towards the Eurasian Plate.
2. The collision creates a convergent boundary causing compression and stress.
3. Sudden release of accumulated stress results in frequent earthquakes.

Question 6.
“During an earthquake study, scientists observed that P-waves passed through a layer of the Earth, but S-waves were not recorded beyond a certain depth”.
What does this observation suggest about the nature of that layer? Explain.
Answer:

1. S-waves cannot travel through liquids.
2. Absence of S-waves suggests the layer is liquid in nature.
3. This proves that the outer core of the Earth is in liquid state.

Question 7.
“A farmer in a hilly region observes that after heavy rainfall, fertile topsoil from the slopes is washed away and deposited in nearby lowlands”. Identify the processes involved and explain how they operate.
Answer:

1. Weathering breaks down rocks into soil particles.
2. Heavy rainfall causes erosion by running water.
3. The eroded soil is transported and deposited in low- lying areas.

Question 8.
Study the diagram given below shows a cross-section of a limestone cave with various formations. Imagine you are a geologist assessing the cave for a tourism site development project. Explain how the pillars in the cave have formed and discuss one potential risk it might pose to the visitors if the cave is opened for the public.

Answer:

1. Formation of pillar: The pillars inside the limestone caves form when a stalactite (hanging from the cave ceiling) and a stalagmite (rising from the cave floor) grow towards each other and eventually merge. This occurs due to the deposition of CaC03 from dripping water in dissolved limestone.
2. Potential risk to visitors: The pillars as well as the stalactites and stalagmites could become unstable if the cave experiences vibrations from foot movement and environmental changes, thus leading to roof collapse.

Question 9.
Analyse the differences between convergent and transform plate boundaries in terms of landform formation and disaster occurrence.
Answer:

1. Convergent boundaries involve collision of plates, leading to mountain formation and volcanic activity, whereas transform boundaries involve plates sliding past each other without creating or destroying crust.
2. Convergent boundaries form fold mountains and ocean trenches, while transform boundaries mainly create fault lines.
3. Earthquakes occur at both, but transform boundaries ‘ primarily generate shallow and frequent earthquakes . without volcanic activity.

Question 10.
“Disaster mitigation is more important than disaster response.” Evaluate this statement with justification.
Answer:

1. Mitigation reduces the intensity of damage before a disaster occurs, saving lives and property.
2. Preventive measures like hazard mapping and building codes reduce long-term economic loss.
3. While response is necessary after disasters, proactive mitigation ensures sustainable safety and preparedness.

Question 11.
Read the passage given below and answer the questions that follow:
In August 2025, a cloudburst and flash floods devastated Dharali in Uttarakhand, drawing comparisons with the 2013 disaster in Kedarnath. News reports highlighted that unregulated construction, fragile Himalayan slopes, heavy rainfall and slope destabilisation worsened the impact. Experts stressed the need for afforestation, slope engineering (retaining walls and drainage) and strict regulation of construction in hilly regions.
(i) Identify one human activity mentioned in the source that increased the scale of destruction.
Answer:
The human activity that has resulted in the large- scale destruction in hilly and mountainous areas is unplanned construction.

(ii) Name one natural factor responsible for the disaster in the Himalayan region.
Answer:
The natural factors responsible for the disaster in the Himalayan region are fragile Himalayan slopes and extreme rainfall.

(iii) Suggest two mitigation measures that could reduce the impact of such disasters in hilly regions. Justify your answer.
Answer:
(a) Promote afforestation: Trees bind the soil and increase slope stability.
(b) Construct retaining walls and proper drainage systems: These prevent water accumulation and reduce slope failure.