Shaping of the Earth’s Surface — full solutions
Every in-text activity and every end-of-chapter question from the chapter, answered in full — with the original diagrams and photographs, and step-by-step explanations where the topic needs them.
“Let’s Map” & “Let’s Explore” boxes
Any two plates can be picked from the map. Two worked examples are filled in below — you may replace these with any other pair from Fig. 2.3.
| Name of the plate | Continents it carries | Ocean(s) associated with it |
|---|---|---|
| Indo-Australian Plate | Indian subcontinent (part of Asia) and Australia | Indian Ocean |
| North American Plate | Most of North America, Greenland and part of Siberia | Parts of the Arctic Ocean, Atlantic Ocean and Pacific Ocean |
Notice that a single plate can carry more than one continent, and can touch more than one ocean — this is because plate boundaries almost never coincide with the edges of continents or oceans.
When the two maps are placed side by side, a clear pattern emerges: the red dots (earthquake origins) and black triangles (active volcanoes) in Fig. 2.4 line up almost exactly along the coloured boundaries where the plates in Fig. 2.3 meet.
- The thick band of activity that rings the Pacific Plate corresponds to the famous “Ring of Fire”.
- A thin but continuous line of activity runs along the mid-Atlantic, matching the boundary between the North/South American plates and the Eurasian/African plates — this marks the Mid-Atlantic Ridge, a divergent boundary.
- A dense cluster runs along southern Asia, exactly where the Indo-Australian Plate is pushing into the Eurasian Plate — this is the Himalayan collision zone.
- In contrast, the interiors of plates — central Africa, the interior of Australia, central Russia, and the heart of North America — show almost no earthquakes or volcanoes at all, because they are far from any plate edge.
Conclusion: earthquakes and volcanoes are not scattered randomly across the globe — they are concentrated almost entirely along tectonic plate boundaries, confirming that plate movement is the primary cause of both phenomena.
The Ring of Fire is the horseshoe-shaped belt of intense seismic and volcanic activity that traces almost the entire rim of the Pacific Ocean. Using an atlas, the continents and countries lying along it can be listed as:
- Along the eastern Pacific (the Americas): the western coasts of the United States (Alaska and California), Mexico, Guatemala, and down the Andes through Colombia, Ecuador, Peru and Chile.
- Along the western Pacific (Asia–Oceania): Russia (Kamchatka Peninsula), Japan, Taiwan, the Philippines, Indonesia, Papua New Guinea, and New Zealand.
- Connecting arc: the Aleutian Islands of Alaska link the eastern and western arms of the ring.
Together these regions form an almost continuous loop around the Pacific Plate — the single most active earthquake and volcano zone on Earth.
Yes, India faces a significant earthquake risk. The Indo-Australian Plate, on which India sits, is continuously pushing into the Eurasian Plate, and this ongoing collision is what raised — and still stresses — the Himalayas.
Most vulnerable regions (India’s highest seismic hazard zone, Zone V):
- The entire Himalayan belt — Jammu & Kashmir, Himachal Pradesh, Uttarakhand.
- All of Northeast India (Assam and the neighbouring states).
- The Bihar–Nepal border area.
- The Kutch region of Gujarat (site of the devastating 2001 Bhuj earthquake shown in Fig. 2.5).
- The Andaman & Nicobar Islands.
Why human lives are at risk: these zones combine high seismic activity with dense population, and much of the older or unplanned construction uses unreinforced masonry that cannot flex during ground shaking. When strong shaking strikes, buildings collapse suddenly rather than deforming safely, which is why earthquakes in densely populated Indian cities and towns have historically caused very heavy casualties, as seen in the 2001 Gujarat earthquake.
What caused this situation: the scene was caused by a nearby volcanic eruption. When it erupted, the volcano threw out a huge quantity of hot gases, molten rock and pulverised rock fragments, which settled thickly over the surrounding village, trees and houses.
The grey powder is volcanic ash — extremely fine particles of shattered rock, minerals and volcanic glass that are blasted into the air during an explosive eruption and then fall back to the ground, blanketing everything in a thick grey layer, as seen covering the trees and rooftops in the photograph.
What it tells us about the Earth’s internal forces: it shows that enormous heat and pressure exist inside the Earth, strong enough to melt rock into magma and force it violently up through the crust. This is direct visible evidence that the Earth’s interior is dynamic and energetic — the same internal (endogenic) forces that build volcanoes are also responsible for earthquakes and mountain building.
Types of erosion in the photographs:
- Photo (a) — Water erosion: shows a hillside cut into deep gullies and rills by flowing rainwater, which has stripped away the soil and exposed the bare rock underneath.
- Photo (b) — Wind erosion: shows dry, sandy grassland with a dust haze, where strong wind is lifting and carrying away loose topsoil, typical of arid and semi-arid tracts.
Effect on farmers:
- Water erosion washes away the fertile, nutrient-rich topsoil that crops depend on, cuts fields into unusable gullies, and can damage or uproot standing crops during heavy runoff — all of which lower yields and shrink the area available for farming.
- Wind erosion blows away loose, dry topsoil (worsening soil fertility) and can bury young crops under drifting sand, while also reducing the soil’s moisture-holding capacity, making the land harder to cultivate season after season.
Both processes force farmers into extra work and expense — many adopt contour bunding, terracing, or wind-breaking tree lines to protect their fields, as described in the “Don’t Miss Out” note on the same page.
The Sundarbans is the world’s largest river delta and the world’s largest mangrove forest, formed where the combined waters of the Ganga, Brahmaputra and Meghna rivers meet the Bay of Bengal, spread across the India–Bangladesh border (West Bengal and Bangladesh).
What makes it unique:
- A dense mangrove forest specially adapted to grow in salty, tidal, swampy soil — visible in the photograph as a maze of green vegetation cut through by countless waterways.
- An intricate network of tidal creeks, channels and low islands that shift and reshape constantly.
- It is the only mangrove habitat in the world with a tiger population — home to the Royal Bengal Tiger — along with saltwater crocodiles, spotted deer and a huge variety of birds.
- It is recognised as a UNESCO World Heritage Site and a Biosphere Reserve, and acts as a natural shield that absorbs the force of cyclones and storm surges before they reach inland settlements.
Why tourists visit: people travel there for wildlife safaris and tiger-spotting boat trips, birdwatching, and to experience an ecosystem and landscape found almost nowhere else on Earth.
This is a field-observation activity, so the exact answer depends on where you live. Use the clues below to match what you see near your school or home to the agent that most likely created it:
| What you might observe | Likely agent |
|---|---|
| A river bend, oxbow-shaped pond, or sand/silt banks along a stream | Running water |
| Rippled sand, dust-polished pebbles, or small dunes in a dry area | Wind |
| Rounded hills, cracked boulders, or crumbling rock faces | Weathering (heat/cold, rain, plant roots) |
| A cave, sinkhole, or a spring emerging from rocky ground (limestone areas) | Groundwater |
| A U-shaped valley or large boulders scattered on a valley floor (high-altitude areas only) | Glaciers |
| Cliffs, sea caves, or a sandy beach (coastal areas only) | Waves and currents |
Write down 2–3 landforms you can actually see, note their approximate shape and material, and match each to the agent whose action best explains it — that is exactly what this activity is asking you to practise.
The chapter discusses four landform-related disasters. A compiled reference list — the kind this activity asks you to research and build yourself — looks like this:
| Disaster | Disaster-prone areas | Mitigation measures |
|---|---|---|
| Landslides | Himalayan states (Uttarakhand, Himachal Pradesh, Sikkim, Darjeeling hills) and the Western Ghats | Afforestation on slopes, retaining walls, avoiding construction on steep/unstable land, landslide early-warning systems |
| Avalanches | High Himalayan snow zones such as Kashmir, Himachal Pradesh (Rohtang), Siachen | Avalanche forecasting, restricting travel in high-risk periods, protective snow fences and barriers |
| Glacial Lake Outburst Floods (GLOF) | Himalayan glacial-lake regions of Sikkim, Uttarakhand, and Nepal | Continuous glacial-lake monitoring, controlled draining of excess water, early-warning alerts, restricting settlement in the flood path |
| Sandstorms / dust storms | The Thar Desert (Rajasthan) and adjoining arid tracts of Gujarat | Shelterbelts of trees, weather-based advance warnings, dust-resistant housing design |
For the “recent examples” part of this activity, check current newspapers and government disaster-management (NDMA/SDMA) reports for the latest events in each category and add them to your own list.
“Questions and Activities”
The internal forces of the Earth are ultimately powered by heat energy stored and generated inside the Earth. This heat comes from two main sources:
- Residual primordial heat — heat left over from the intense pressure and collisions that formed the Earth billions of years ago, which the planet is still slowly losing.
- Radioactive decay — the continuous decay of radioactive elements (such as uranium, thorium and potassium) inside the mantle and core, which constantly generates fresh heat.
This heat sets up convection currents in the mantle (Fig. 2.2) — hot material rises, cooler material sinks, in a continuous circulating motion. It is this convective motion that drags the rigid tectonic plates above it, producing the internal-force movements of the Earth: earthquakes, volcanic eruptions, folding and faulting.
| Physiographic division | Endogenic force responsible |
|---|---|
| The Himalayas | Formed by folding at the convergent boundary where the Indo-Australian Plate is still colliding with the Eurasian Plate — this is why the range continues to rise and remains highly earthquake-prone. |
| The Northern Plains | Occupy a trough formed by gentle tectonic subsidence (down-warping) between the rising Himalayas and the stable Peninsular Plateau; later filled with river-borne alluvium. |
| The Peninsular Plateau | Built on an ancient, stable landmass; shaped by very old volcanic eruptions (the Deccan Traps) and by faulting that created rift valleys such as those of the Narmada and Tapi rivers. |
| Coastal Plains | Formed along the edges created when rifting/faulting broke India away from the ancient Gondwana landmass, later modified by marine deposition. |
| Islands (Andaman & Nicobar, Lakshadweep) | Andaman & Nicobar are the exposed peaks of a folded mountain chain linked to subduction (with active volcanism at Barren Island); Lakshadweep islands are coral growths on a submerged volcanic platform. |
Why: earthquakes occur because tectonic plates are in constant, slow motion. As plates push, pull, or slide against one another at their boundaries, enormous stress builds up in the rocks. When the rocks can no longer withstand this stress, they suddenly fracture and release the built-up energy as seismic waves — an earthquake.
Where: earthquakes are concentrated almost entirely along plate boundaries — most frequently along the Pacific “Ring of Fire”, the Alpine–Himalayan belt (where the Indo-Australian and Eurasian plates meet), and the Mid-Atlantic Ridge.
Can they be predicted? Scientists can identify high-risk zones and prepare seismic hazard/zoning maps, and can state the long-term probability of an earthquake in a region — but they cannot yet predict the exact date, time or magnitude of a future earthquake. Some countries do use early-warning systems that detect the first, faster (but less damaging) P-waves and send out a warning of a few seconds to a minute before the more destructive S-waves arrive.
This statement is true, and can be explained through the three types of plate boundaries:
- Convergent boundaries (plates moving towards each other): when an oceanic plate meets a continental plate, the denser oceanic plate sinks (subducts) beneath the continental one, generating deep earthquakes and, as the sinking plate melts, chains of volcanoes — for example, the volcanic arcs around Japan and the Andes. When two continental plates collide, no subduction occurs but the crust folds upward into mountains, as with the earthquake-prone Himalayas.
- Divergent boundaries (plates moving apart): magma rises to fill the gap and forms new crust, producing shallow earthquakes and volcanic activity — visible along the Mid-Atlantic Ridge and the East African Rift Valley.
- Transform boundaries (plates sliding past each other): friction between the sliding plates causes frequent earthquakes but little or no volcanic activity — the San Andreas Fault in the USA is the classic example.
Because these three boundary types trace the outlines of the plates themselves, the world map of earthquakes and volcanoes (Fig. 2.4) closely mirrors the map of plate boundaries (Fig. 2.3) — confirming that plate movement, not chance, decides where these events occur.
Redraw the two diagrams above in your notebook with the four labels marked on each. A short note to accompany each diagram:
Meander: a winding bend that develops in the middle or lower course of a river. The river erodes the outer (steep) bank, where the current is fastest, and deposits sediment as a bar along the inner bank, where the current is slowest. Repeated over time, this makes the river’s course loop more and more; if a loop is eventually cut off from the main channel, it is left behind as a crescent-shaped oxbow lake.
Delta: forms where a river meets a sea, ocean or lake and suddenly loses velocity, dropping the sediment load it has carried from upstream. Over time this sediment builds up into a fan-shaped landmass; the single river channel splits into several smaller channels called distributaries, which wind between built-up islands and bars before finally reaching the sea.
Deforestation and erosion are closely linked, and one accelerates the other:
- Tree roots bind the soil together in a dense underground network. When trees are cut down, this binding disappears, and the loose soil is easily picked up by running water or wind.
- Tree canopies break the force of rainfall before it hits the ground. Without this cover, raindrops strike bare soil directly, loosening particles that are then carried away by surface runoff.
- Forest litter and roots increase infiltration, letting water soak into the ground rather than run off. Once the forest is gone, infiltration drops, and more rainwater flows across the surface, sweeping topsoil with it and cutting gullies into slopes.
The result is a self-reinforcing cycle: deforestation exposes soil to erosion, and this erosion strips away the very topsoil new plants would need to take root, making it harder for the forest to recover and leaving the land progressively barer and less fertile.
A practical, low-cost soil-conservation plan can combine the following measures (choose the ones suited to your local terrain and adapt them to your own area’s specifics):
- Afforestation and shelterbelts — plant trees along field boundaries and slopes to bind soil and break wind speed.
- Contour bunding and contouring — plough and build small earthen bunds along the natural contour of a slope, so that rainwater is slowed rather than allowed to rush straight downhill.
- Terracing — convert steep farmland into a series of level steps to reduce the speed of surface runoff.
- Check dams — build small dams across seasonal streams to slow water flow and let sediment settle instead of washing away.
- Maintaining vegetative/cover crops — never leave farmland completely bare between cropping seasons.
- Controlled grazing — prevent overgrazing, which strips protective grass cover from the soil.
- Community monitoring — organise periodic checks by residents/students to spot new gullies or bare patches early, before they widen.
This answer will vary by where you live — use the chapter’s four disaster types as your starting checklist, and discuss the matching plan in class:
| If your region is… | Likely disaster | Mitigation discussion points |
|---|---|---|
| Hilly / Himalayan | Landslides, avalanches, GLOF | Slope stabilisation, avoiding construction on steep land, glacial-lake monitoring, evacuation drills |
| Arid / semi-arid (e.g. Rajasthan, Gujarat) | Sandstorms, dust storms | Shelterbelts, dust-resistant housing, advance weather alerts |
| Coastal | Coastal erosion, storm surge | Mangrove restoration, sea walls, early cyclone warning |
| River plains | Flooding, bank erosion | Embankments, flood forecasting, controlled drainage |
In your classroom discussion, list the one or two disaster types most relevant to your own town or village, and note practical, low-cost mitigation steps your school or community could realistically carry out.
A simple working model can be built using easily available craft materials:
- Materials: a shoebox or thermocol base, clay/plaster of Paris or papier-mâché, brown and grey paint, cotton or foil for water, cardboard.
- Build the cave: hollow out a cavity inside the block of clay/plaster to represent a limestone cave.
- Add stalactites and stalagmites: use small cones of plaster or clay hanging from the “ceiling” (stalactites) and rising from the “floor” (stalagmites); where they meet, shape a pillar — exactly as labelled in Fig. 2.24.
- Add a sinkhole: shape a funnel-like depression on the model’s surface leading down into the cave, to represent how surface ground collapses into an underlying cavity.
- Add an underground river: lay a thin strip of blue foil or paint through the base of the cave to represent water flowing through the cave system, as in Fig. 2.26.
- Label each part — cave, stalactite, stalagmite, pillar, sinkhole, underground river — using small flags or a printed key, and present the model along with a short explanation of how groundwater dissolving limestone rock creates each feature.
Before an earthquake:
- Ensure the house is built (or retrofitted) to earthquake-resistant design standards.
- Secure heavy furniture, shelves and appliances to walls so they cannot topple.
- Keep an emergency kit ready — torch, first-aid box, drinking water, and a battery/solar radio.
- Plan and practise a family evacuation route and identify a safe outdoor meeting point.
During an earthquake:
- Follow “Drop, Cover, and Hold On” — drop to the ground, take cover under a sturdy table, and hold on until the shaking stops.
- Stay away from windows, mirrors, and tall unsecured furniture.
- If outdoors, move to open ground, away from buildings, trees, and power lines.
After an earthquake:
- Check yourself and others for injuries before moving around.
- Be prepared for aftershocks, and avoid entering damaged buildings.
- Follow instructions from official emergency and disaster-management authorities.
This is a research-based mapping activity. A suggested method:
- Take a blank outline map of India (or the world, depending on your teacher’s instruction).
- Go through newspaper archives, government disaster-management (NDMA) bulletins, and reliable news sources for the current year.
- Note down each landform-related disaster you find — landslides, avalanches, GLOF events, sandstorms, floods caused by erosion, etc. — along with its location and date.
- Mark each event on your map using a distinct symbol for each disaster type (e.g., a triangle for landslides, a snowflake for avalanches), and add a legend.
- Write one line under each marked location describing what happened.
Once complete, the map will visually show you which parts of the country/world faced the most landform-related disasters this year.
This activity depends on your own region, but here are well-known examples from across India to use as a model for the format of your poster:
- Amarnath Cave (Jammu & Kashmir) — a natural ice-stalagmite cave regarded as sacred to Lord Shiva; the subject of the Amarnath Yatra pilgrimage.
- Gangotri (Uttarakhand) — the glacial source of the River Ganga, considered the earthly point where the goddess Ganga descended to Earth.
- Nanda Devi Peak (Uttarakhand) — worshipped as a form of the goddess Nanda Devi, and the centrepiece of local folk festivals.
- Vindhya Range — associated in folklore with the sage Agastya, said to have humbled the range’s height.
For your own poster: pick one or two landforms (a hill, river, cave, or rock formation) that are locally considered sacred, sketch or photograph them, and write the folk story or belief associated with each — exactly as in the examples above.
Document your own region’s disaster using the structure below — a worked example is shown using the 2001 Gujarat earthquake mentioned in the chapter (Fig. 2.5):
- Disaster: Bhuj earthquake, Gujarat.
- Date: 26 January 2001.
- Cause: sudden release of stress along a fault in the Kutch region, an area of ongoing tectonic activity.
- Effect on life: tens of thousands of deaths and injuries; large-scale destruction of homes, leaving many families homeless.
- Effect on property/economy: widespread collapse of buildings and infrastructure (as seen in Fig. 2.5), heavy losses to local industry and trade.
- Relief and recovery measures: national and international rescue operations, temporary shelters, and long-term reconstruction using improved earthquake-resistant building codes.
Replace this example with a disaster (of any scale) that has actually affected your own town, district, or state, using newspaper reports or family/community accounts as your source.
The poster’s key safety message is organised into three stages. Use the English text below as your base, and translate each line into your own native language:
Before: grow more trees that can hold the soil together; listen to radio/watch TV and read newspapers for alerts; keep drains clean, keep holes open; watch for warning signs such as unusual sounds like cracking or boulders knocking together; do not construct on steep slopes or near drainage paths.
During: stay calm, do not panic, ignore rumours; stay together with your companions; if you notice warning signs, move away from the landslip path or downstream valley quickly; inform the nearest Tehsil/District headquarters.
After: do not touch or walk over loose material and electrical wires or poles; move away from the landslide path and downstream valley quickly; check for injured and trapped persons; do not move an injured person without rendering first aid unless they are in immediate danger; do not drink contaminated water directly from rivers, springs or wells.
Use the same four-part structure for whichever agent your group is assigned:
| Group | Causes (how the agent erodes/shapes land) | Impact on human life & environment | Mitigation measures |
|---|---|---|---|
| Water | Flowing rivers and rainfall erode, transport, and deposit sediment, forming valleys, meanders, floodplains and deltas | Fertile floodplains support farming and settlement, but flooding and bank erosion damage property and displace people | Embankments, afforestation along riverbanks, flood forecasting and warning systems |
| Wind | Wind picks up and deposits loose sand in arid regions, forming dunes and eroded rock features | Dust storms reduce visibility and air quality and bury farmland; but also creates unique desert ecosystems and tourism | Shelterbelts of trees, wind-breaks, stabilising dunes with vegetation |
| Glacier | Moving ice scrapes and carries rock, carving U-shaped valleys and depositing moraines | Glacial meltwater feeds major rivers and supports agriculture downstream, but glacial lake outburst floods (GLOF) threaten mountain communities | Glacial lake monitoring, controlled draining of lakes, early-warning systems in high-altitude settlements |
Each group should present their assigned row in more depth — with real examples, sketches, and at least one recent case study — as a short class presentation.
That’s the full chapter, solved.
All 9 in-text activities and all 15 exercise questions from “Shaping of the Earth’s Surface” — answered in full, with the chapter’s own diagrams and photographs alongside each solution.