Class 9 · Social ScienceNCERT 2026 Revised Syllabus

Chapter 2: Shaping of the Earth's Surface (0908CH02)

Understanding Society India and Beyond

Explores how internal forces like plate tectonics and external forces like weathering and erosion continuously transform the Earth's surface and form diverse landforms.

Chapter code: 0908ch02 · Book: Understanding Society India and Beyond · Class 9 Social Science

Find complete NCERT solutions for Class 9 Social Science, Understanding Society India and Beyond Chapter 2. Every question has a clear, step-by-step answer for chapter code 0908CH02.

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The Big Questions(5 questions)

What shapes the Earth's surface?

Ans.

Internal forces (plate movement, earthquakes, volcanic eruptions, folding, faulting) and external forces (weathering, erosion, deposition by water, wind, glaciers) together shape the Earth's surface.

What is plate tectonics? What are the effects of plate movement?

Ans.

Plate tectonics explains that the Earth's crust is broken into moving plates. Their movement causes mountains, earthquakes, volcanoes, and the formation of new landforms.

How are landforms formed and how are they classified?

Ans.

Landforms form through internal forces (plate movement) and external agents (water, wind, glaciers, groundwater). They are classified as fluvial, glacial, aeolian, coastal, and karst landforms.

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

Ans.

Landforms provide fertile soil, water, settlement sites, and livelihoods such as farming, fishing and tourism, while also shaping climate, culture, and exposure to natural hazards.

How do disasters associated with different landforms impact human lives?

Ans.

Landform-related disasters like landslides, avalanches, GLOFs, and dust storms cause loss of life, property damage, and disruption of infrastructure, agriculture, and connectivity.

Plate Tectonics(5 questions)

Activity — LET'S MAP: Complete the table for any two plates (name of the plate, continents, ocean).

Ans.

Name of the Plate	Continents	Ocean
Eurasian Plate	Europe and most of Asia	Parts of the Arctic and North Atlantic Ocean
Pacific Plate	No major continent (mostly oceanic plate)	Pacific Ocean

Activity — LET'S EXPLORE: What is the correlation between the plate map and the earthquake/volcano map?

Ans.

Most earthquakes and volcanoes occur along plate boundaries, especially around the Pacific Ocean rim (the Ring of Fire), showing that plate edges are the most tectonically active zones.

Activity — LET'S EXPLORE: Which continents/countries lie around the Ring of Fire?

Ans.

Japan, Indonesia, the Philippines, the USA (Alaska, California), Chile, New Zealand, and Russia lie around the Pacific Ring of Fire, spanning Asia, North America, South America, and Oceania.

Activity — LET'S EXPLORE: Does India have a risk of earthquakes? Which region is vulnerable, and why are lives at risk?

Ans.

Yes. The Himalayan belt and North-East India are most vulnerable due to active plate collision. Dense population and weak construction in these areas increase risk to human life.

Look carefully at this photograph and answer the following questions.

a.What do you think caused this situation?
b.What could that grey powder be?
c.What does it tell us about the Earth’s internal forces?

Ans.

a. The situation was caused by a volcanic eruption. b. The grey powder is volcanic ash/deposited volcanic material. c. It shows that internal forces of the Earth can produce volcanic eruptions and bring material from inside the Earth to the surface.

Process of Weathering and Erosion(1 questions)

Activity — LET'S EXPLORE: How are farmers affected by water erosion and wind erosion (Fig. 2.9)?

Ans.

Water erosion washes away fertile topsoil and can flood fields, while wind erosion blows away loose soil in dry regions; both reduce soil fertility and lower crop yields for farmers.

Agents of Gradation — Running Water(1 questions)

Activity — LET'S EXPLORE: What makes the Sundarbans delta unique and popular with tourists?

Ans.

The Sundarbans, formed by the Ganga–Brahmaputra delta, is unique for its dense mangrove forests and Royal Bengal Tigers, attracting tourists for wildlife viewing and eco-tourism.

Glaciers(1 questions)

Activity — THINK ABOUT IT: What were the reasons behind the sudden Chamoli (Uttarakhand) flood of February 2021?

Ans.

The disaster was caused by a glacier/rock avalanche that triggered a sudden glacial lake outburst, releasing huge volumes of water and debris down the Rishiganga valley.

Underground Water(1 questions)

Activity — LET'S EXPLORE: Identify the agent that created landforms around your school/residence.

Ans.

Sample answer: Small gullies near a school may form due to water erosion in monsoon rains, while cracked walls or rocks nearby show physical weathering from daily temperature changes.

Landforms and Disasters(4 questions)

Activity — LET'S EXPLORE: Complete the exercise for Landslides — prone areas, mitigation measures and recent examples.

Ans.

Prone areas: Himalayan states (Uttarakhand, Himachal Pradesh, Sikkim), the Western Ghats, and hilly North-Eastern states with steep, unstable slopes. Mitigation measures: Afforestation, terracing, retaining walls, proper drainage, avoiding construction on steep slopes, and early warning systems. Recent examples: Wayanad landslide, Kerala (2024); Joshimath land subsidence, Uttarakhand (2023).

Activity — LET'S EXPLORE: Complete the exercise for Avalanches — prone areas, mitigation measures and recent examples.

Ans.

Prone areas: High-altitude, snow-covered regions such as Jammu & Kashmir and Himachal Pradesh; also the Alps and the Rockies worldwide. Mitigation measures: Avalanche forecasting, controlled release of snow, protective barriers, and restricting activity in high-risk zones during heavy snowfall. Recent examples: Avalanche near Sonamarg, Jammu & Kashmir (2024), affecting a road-construction camp.

Activity — LET'S EXPLORE: Complete the exercise for Glacial Lake Outburst Floods (GLOFs) — prone areas, mitigation measures and recent examples.

Ans.

Prone areas: Glacial regions of the Himalayas, including Sikkim, Uttarakhand, and Himachal Pradesh. Mitigation measures: Regular monitoring of glacial lakes, early warning systems, controlled draining of lake water, and limiting settlements in vulnerable valleys. Recent examples: South Lhonak Lake GLOF, Sikkim (2023), which damaged the Teesta hydel project.

Activity — LET'S EXPLORE: Complete the exercise for Dust Storms — prone areas, mitigation measures and recent examples.

Ans.

Prone areas: Arid and semi-arid regions such as Rajasthan, parts of Gujarat, and the Thar Desert. Mitigation measures: Planting wind-breaking trees, controlling overgrazing, improving farming practices, and issuing timely weather warnings. Recent examples: Severe dust storms across Delhi-NCR and Rajasthan (May 2018) that caused deaths and property damage.

Questions and Activities (End of Chapter)(15 questions)

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

Ans.

Heat from radioactive decay inside the Earth and residual heat from its formation drive mantle convection currents, which push tectonic plates and power the Earth's internal forces.

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

Ans.

Relate each physiographic division to the processes responsible for it. The Himalayas are fold mountains formed by convergence of the Indian and Eurasian plates. The Peninsular Plateau is an ancient, relatively stable landmass whose relief has also been shaped by long-term tectonic movements and denudation. The Northern Plains were formed mainly by deposition of sediments by rivers, so they are an exogenic rather than an endogenic feature.

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

Ans.

Earthquakes occur mainly along plate boundaries due to sudden release of built-up stress, especially around the Ring of Fire. Exact timing cannot be predicted, though risk zones can be identified.

"Plate movements are responsible for the distribution of earthquakes and volcanoes." Explain.

Ans.

Most earthquakes and volcanoes occur where plates converge, diverge, or slide past each other; boundary stress and rising magma at these zones directly cause such events worldwide.

Draw and label a diagram of a meander and a delta.

Ans.

Draw a meander showing the winding river bend, oxbow lake, steep outer bank, and inner bar (as in Fig. 2.11); draw a delta showing the river, distributaries, islands/bars, and the sea (as in Fig. 2.12).

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

Ans.

Tree roots bind soil together; deforestation removes this cover, exposing bare soil to rain and wind, which increases erosion, soil loss, and land degradation.

Develop a plan to protect the land in your local area from erosion.

Ans.

Sample plan: plant trees and grass cover, build bunds/terraces on slopes, construct check dams, avoid overgrazing, and promote contour farming to control local soil erosion.

Which disasters do you think you might experience in your region? Discuss a mitigation plan in your classroom.

Ans.

Sample (river-plain region): floods from river overflow are the main risk; mitigation includes embankments, early flood warnings, improved drainage, and community preparedness plans.

Prepare a model of landforms created by underground water.

Ans.

Build a clay or thermocol model showing a cave with stalactites and stalagmites, a sinkhole, and an underground river, together depicting Karst topography.

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

Ans.

Keep an emergency kit ready, secure heavy furniture, know safe spots like under sturdy tables, avoid lifts during a quake, and follow earthquake-resistant building practices.

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

Ans.

Mark the locations and types of landslides, avalanches, GLOFs, and dust storms reported this year on an outline map of India/the world, using newspapers or verified news sources.

Create a poster showing landforms considered sacred or important in your region, with folk stories associated with them.

Ans.

Sample: a poster on the river Ganga and Himalayan peaks can include folk stories of their divine origin, highlighting their cultural and religious importance in Indian tradition.

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

Ans.

Sample: a regional flood disrupted farming, damaged homes and roads, displaced families, and affected schooling, showing how landform-related disasters impact many aspects of life.

Translate the given poster on landslide into your native language and display it in your home.

Ans.

Translate the landslide-awareness poster from the chapter into your mother tongue (for example, Hindi) and display it at home to spread disaster awareness within the family.

Divide the class into three groups (water, wind, and glacier). Each project should highlight causes, impact on human life and environment, and mitigation measures.

Ans.

Each group should explain how water-, wind-, or glacier-related landforms and disasters form, describe their effects on settlements, agriculture, and environment, and list suitable mitigation measures.

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