Shaping of the Earth’s Surface — Key Terms, Practice Questions and Answers
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Shaping of the Earth’s Surface — Key Terms, Practice Questions and Answers

Ch 2 — Shaping of the Earth’s Surface
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This MCQ module is based on: Shaping of the Earth’s Surface — Key Terms, Practice Questions and Answers

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Key Terms

Tap each card to flip it and check the meaning.

Landformtap to flip
A natural feature of the Earth's surface, such as a mountain, valley, plateau, plain or dune.
Crust / mantle / coretap to flip
The three main layers of the Earth, from outside to inside.
Lithospheretap to flip
The rigid outer shell (crust + upper mantle), broken into plates.
Asthenospheretap to flip
The hot, soft, partly molten layer beneath the lithosphere.
Tectonic platetap to flip
A huge slab of lithosphere that moves a few centimetres a year.
Convection currenttap to flip
The circular movement of hot material rising and cool material sinking.
Plate boundarytap to flip
The edge where two plates meet: convergent, divergent or transform.
Subductiontap to flip
The sinking of one plate beneath another.
Ring of Firetap to flip
The belt of frequent earthquakes and volcanoes around the Pacific Ocean.
Magma / lavatap to flip
Molten rock underground / molten rock that reaches the surface.
Weatheringtap to flip
Breaking down of rocks in place, without movement.
Erosiontap to flip
Wearing away and carrying away of rock and soil.
Depositiontap to flip
Dropping of material when the carrying agent slows down.
Agents of gradationtap to flip
Running water, glaciers, wind, waves and groundwater that level the land.
Meander / oxbow laketap to flip
A loop in a river / a lake left when a meander is cut off.
Delta / distributarytap to flip
Land built of sediment at a river's mouth / a branch channel within it.
Morainetap to flip
A ridge of rock debris deposited by a glacier.
Karst topographytap to flip
Landforms produced when water dissolves limestone.
Contouring, bunding, terracingtap to flip
Traditional ways of slowing water on slopes to prevent soil erosion.
GLOFtap to flip
Glacial Lake Outburst Flood.

Practice Questions

🎯 A. Multiple Choice — instant feedback

Pick an answer to see at once whether it is right, and why.

1. The layer on which tectonic plates move is the:
2. The Himalaya were formed at a:
3. Which process does not involve the movement of material?
4. A crescent-shaped lake left behind when a river cuts off a loop is a(n):
5. Stalactites and stalagmites are formed by:
6. The Ring of Fire surrounds the:

🎯 Internal or external force?

The Earth's surface is built up by internal forces and worn down by external ones. Which is at work?

Two continental plates push together and raise a mountain range.
A river carves a V-shaped valley.
Magma erupts through a volcano.
Wind blows sand into a dune.
An earthquake shakes the ground.
A glacier scoops out a U-shaped valley.

B. Short Answer Questions (30–50 words)

7. Distinguish between weathering and erosion, with one example of each.
Answer: Weathering breaks rocks down in place without moving them, e.g. roots splitting a rock. Erosion wears rock and soil away and carries it elsewhere using water, wind, ice or waves, e.g. a river carrying soil downstream.
8. What are convection currents, and how do they move tectonic plates?
Answer: Heat from the core makes hot mantle rock rise, spread under the lithosphere, cool and sink again in a continuous loop. These convection currents drag, push and pull the plates resting on them.
9. Why do most earthquakes and volcanoes occur along plate boundaries?
Answer: Plate boundaries are where plates collide, pull apart or grind past each other. Stress builds up and is released as earthquakes, and melting at subduction zones or rising magma at divergent zones feeds volcanoes.
10. How does a waterfall form?
Answer: Where a river flows over hard rock lying above soft rock, the soft rock erodes faster. This undercuts the hard rock, creating a steep drop; falling water and boulders scour a plunge pool at the base, and the overhang eventually collapses so the fall moves upstream.
11. Name three erosional landforms made by sea waves and explain how one of them forms.
Answer: Sea cliffs, sea caves, arches, stacks and wave-cut platforms. Example: waves attack weak points on both sides of a headland to form caves; when the caves meet, they form an arch; when the arch roof collapses, a stack is left standing.

C. Long Answer Questions (80–120 words)

12. What sources of energy drive the internal forces of the Earth?
Answer: Mainly the Earth's internal heat, left over from the planet's formation and produced by the decay of radioactive elements in the mantle and crust. This heat drives convection in the mantle (moving plates), melts rock into magma, and powers volcanic activity and earthquakes. The pull of gravity on cooling, sinking plates also helps.
13. "Plate movements are responsible for the distribution of earthquakes and volcanoes." Explain.
Answer: The lithosphere is broken into plates that move over the asthenosphere. At convergent boundaries, collision and subduction cause strong earthquakes and volcanoes (e.g. the Andes, Japan); at divergent boundaries magma rises, causing volcanic activity (Mid-Atlantic Ridge, Iceland); at transform boundaries plates grind past each other, causing earthquakes (San Andreas). So on a world map, earthquakes and volcanoes line up along plate boundaries, especially the Ring of Fire.
14. Why and where do earthquakes occur frequently? Is it possible to predict them?
Answer: Earthquakes are frequent along plate boundaries — the Ring of Fire, the Himalaya–Alpine belt (including northern and north-eastern India) and mid-ocean ridges — because stress builds up where plates meet and is released suddenly. Scientists can identify where earthquakes are likely and how strong they might be, but they cannot yet predict exactly when one will occur. That is why earthquake-resistant buildings, preparedness drills and early-warning systems matter.
15. How are deforestation and erosion linked? Suggest ways to reduce erosion in your area.
Answer: Tree roots bind soil and leaves break the force of rain. When forests are cleared, rain and wind strip away the exposed topsoil, forming gullies on slopes and causing silt to fill rivers. To reduce erosion: plant trees and grass, terrace and bund slopes, build check dams, avoid overgrazing and keep fields covered with crops or mulch.
16. Explain the causes of any two landform-related disasters and suggest mitigation measures for each.
Answer (any two): Landslides: heavy rain, earthquakes, steep slopes, deforestation and road-cutting; mitigate with afforestation, retaining walls, drainage and hazard maps. Dust storms: drought, dry loose soil and sparse vegetation; mitigate with shelterbelts, dune fixing and grazing control.

D. Diagrams, Maps and Projects

17. Draw and label a diagram of a meander and of a delta.
Hints: Meander: label the outer bank (erosion, steep), inner bank (deposition, sand bar), direction of flow and, if you wish, an oxbow lake. Delta: label the river, distributaries, sediment, the sea and the fan or triangular outline.
18. Relate the physiographic divisions of India you studied in earlier grades (the Himalaya, the Northern Plains, the Peninsular Plateau, the coastal plains, the islands) to the forces that formed them.
Answer: The Himalaya were formed by folding at a convergent boundary; the Northern Plains by deposition from Himalayan rivers; the Peninsular Plateau is an old, stable block shaped by long weathering and erosion and by volcanic lava (the Deccan Traps); the coastal plains by deposition and wave action; the Andaman and Nicobar Islands by plate movement, and Lakshadweep by coral growth.
19. On an outline map, mark the landform-related disasters that have happened in India during the current year.
Hints: use a newspaper or a government disaster-management website; give each hazard its own symbol (for example a triangle for landslides, a star for avalanches) and add a key with the place and month.
20. Make a model of the landforms created by underground water.
Hints: use clay or paper-mash for a limestone block; show a sinkhole at the top, a cave below, stalactites hanging from the roof, stalagmites rising from the floor, a pillar where they meet, and an underground river.
21. What precautions would you take if you lived in an earthquake-prone region?
Hints: during shaking, drop, cover and hold on under sturdy furniture and stay away from windows; know the safe spots and exits at home and school; secure heavy furniture; keep an emergency kit; use earthquake-resistant construction; take part in drills.
22. Create a poster of landforms that are sacred or important in your region, with the folk stories linked to them.
Hints: interview elders for the stories; name the landform (hill, river, cave, lake) and the agent that formed it; add a photograph or drawing and one line on why it matters to local people.
23. Group project: divide the class into three groups — water, wind and glaciers. Each group presents the landforms, their impact on people and the environment, and ways to reduce the risks.
Hints: use the "agents of gradation" tab in Part 2 as a starting outline: landforms (erosional and depositional), how people use them, the risks (floods, dust storms, glacial floods) and the mitigation measures.
THINK ABOUT IT — Chamoli, February 2021
Bloom: L4 Analyse

A sudden, devastating flood struck the Chamoli district of Uttarakhand. What caused it?

✅ Pointers
Scientists traced the flood to a massive rock and ice avalanche that broke off a steep mountainside in the Ronti Gad valley. It turned into a fast-moving debris flow down the Rishiganga and Dhauliganga rivers. Rising temperatures and weakened, fractured rock are thought to have contributed.

Answer Key Summary

✅ MCQ Answers
1 → (c) · 2 → (c) · 3 → (b) · 4 → (b) · 5 → (c) · 6 → (c)

📝 Competency-Based Questions — Chapter 2 Practice

Ravi's class studies a map of the world with plate boundaries drawn as lines. He notices that Japan, Chile and Indonesia all lie on the edge of the Pacific. A news item tells them that a strong earthquake struck a mountain village in the Himalaya, and a week later heavy rain caused a landslide on the same slope. In science class they built a model of a river with a waterfall.
Q1. Why are Japan, Chile and Indonesia all prone to earthquakes and volcanoes?
L2 Understand
Model Answer: They lie on the Pacific's Ring of Fire, where several plates meet. Collision, subduction and grinding of plates there build up stress and feed volcanoes.
Q2. Explain how the earthquake could have made the landslide a week later more likely.
L4 Analyse
Model Answer: Earthquakes shake and weaken slopes, opening cracks in soil and rock. When heavy rain later soaked the ground, adding weight and reducing friction, the weakened slope failed. So an internal force (plate movement) and an external factor (rain) worked together.
Q3. In Ravi's waterfall model, which rock layer should be at the top, and why does the waterfall slowly move upstream?
L3 Apply
Model Answer: A layer of hard rock at the top, above softer rock. The soft rock wears away faster, undercutting the hard rock; the overhang collapses and the fall retreats upstream.
Q4. Assess the statement: "Since earthquakes cannot be predicted, preparation is pointless."
L5 Evaluate
Model Answer: The statement is weak. Scientists can say where earthquakes are likely and how strong they might be, though not exactly when. Earthquake-resistant buildings, drills and early-warning systems save lives precisely because timing is uncertain.
⚖️ Assertion–Reason Questions — Chapter 2
Options:
(A) Both A and R are true, and R is the correct explanation of A.
(B) Both A and R are true, but R is NOT the correct explanation of A.
(C) A is true, but R is false.
(D) A is false, but R is true.
Assertion (A): Most earthquakes and volcanoes occur along plate boundaries.
Reason (R): Stress builds up where plates collide, pull apart or slide past each other.
Answer: (A) — Both true and R explains A. The Ring of Fire is the best-known example.
Assertion (A): Meanders form where a river flows fastest on the inner bank of a bend.
Reason (R): A river erodes the outer bank of a bend and deposits on the inner bank.
Answer: (D) — A is false, R is true. Water flows fastest on the outer bank, which is eroded; the inner bank, where water is slow, gets the deposit.
Assertion (A): Glaciers are important sources of fresh water.
Reason (R): Glaciers feed rivers such as the Ganga and Indus that sustain hundreds of millions of people downstream.
Answer: (A) — Both true and R explains A.

Frequently Asked Questions

What are the important questions from Class 9 Social Science Chapter 2, Shaping of the Earth's Surface?

Layers of the Earth, plate tectonics and boundary types, convection currents, the Ring of Fire, weathering versus erosion, river landforms (waterfall, meander, delta), glacial, wind, wave and karst landforms, and disasters such as landslides, avalanches, GLOFs and dust storms.

What is the difference between weathering and erosion?

Weathering breaks rocks in place; erosion carries the material away by water, wind, ice or waves.

Which plate boundary formed the Himalaya?

A convergent boundary between two continental plates, the Indian and Eurasian plates.

Can earthquakes be predicted?

Scientists can identify where earthquakes are likely and how strong they might be, but not exactly when. Preparedness, resistant buildings and early warnings therefore matter.

Illustrations: AI-generated on Hugging Face and labelled by our editors. Charts and maps are drawn from cited data. Notes follow the NCERT textbook Understanding Society: India and Beyond — Grade 9, Part 1 (NCERT).

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