NCERT Solutions Class 9 Social Science Chapter 10 Oceans and Life

F R E E S T U D Y M AT E R I A L F O R E V E R Y S T U D E N T

CLASS 9 · SOCIAL SCIENCE

NCERT Solutions

Chapter 10: Oceans
and Life

NCERT Textbook — Understanding Society: India
and Beyond

BOOK PAGES SECTIONS QUESTIONS MEDIUM

Part II, 1 – 20 10 24 English

Every question Step by step Exam ready
Activities, in-text questions The working shown, not Written to match how
and all exercises. just the final answer. marks are awarded.

Solutions, notes, sample papers & more at 37 pages

Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

CLASS 9 · SOCIAL SCIENCE · UNDERSTANDING SOCIETY: INDIA AND BEYOND

NCERT Solutions — Chapter 10: Oceans and Life
This chapter (Part II, Chapter 1) takes you below the sea surface and along the coast. It explains ocean relief,
the three movements of ocean water (waves, tides and currents) and the early warning systems that
protect coasts from cyclones and tsunamis. It then covers marine resources, the Blue Economy, and the
maritime zones and rules that decide who may use which part of the sea. By the end you should be able to
explain how oceans shape climate, livelihoods and safety, and why they must be used sustainably.

TEXTBOOK BOOK PAGES
Understanding Society: India and Beyond (Class 9) Part II, 1 – 20

SECTIONS QUESTIONS
10 24

MEDIUM
English

The Big Questions — Page 1
Chapter opener
THE BIG QUESTIONS

Q1 What is the importance of ocean relief?

Ocean relief (submarine relief) is the set of landforms on the ocean floor: continental shelf,
continental slope, abyssal plains, mid-ocean ridges, seamounts and trenches. It is important
because:
Resources and fishing: the shallow continental shelf is rich in marine life and in oil and gas
(page 3).
Ocean movements: the shape of ocean basins guides currents, and shallow floors near the
coast make waves and tides rise higher.
Navigation: ships need enough depth. Very large tankers cross shallow channels such as
the Singapore Strait only at high tide.
Hazards: trenches mark zones where undersea earthquakes can set off tsunamis.
Maritime rights: a country’s continental shelf is part of the sea area over which it has rights
(Fig. 1.20).
So ocean relief decides where life is rich, where ships can sail, where resources lie and where
danger comes from.

Page 1 of 37

Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

− Explanation

Relief is really about depth, and depth controls almost everything else in the sea: how
much sunlight gets in, how cold and dark the water is, and how much pressure a living
thing or a machine must survive.
The Mariana Trench in the Pacific Ocean is the deepest place on Earth, about 11 km
deep (page 2).
The Mid-Ocean Ridge is the world’s longest mountain range, hidden under the sea.
Some underwater mountains, such as Mauna Kea in Hawai‘i, are taller than Mount
Everest when measured from their base on the sea floor.

Why: fishing communities, port engineers, cable layers and oil companies all
need maps of the sea floor. That is why the GEMINI device gives fishermen
bathymetry data, the mapping of underwater relief (page 11).

Did you know? Mauna Kea rises only about 4,200 m above sea level, but
measured from its base on the ocean floor it is over 10,000 m tall. Mount
Everest is 8,849 m above sea level.

Q2 How does ocean water movement impact life and environment?

Ocean water moves in three ways, and each one affects life and the environment:

MOVEMENT IMPACT ON THE ENVIRONMENT IMPACT ON LIFE AND PEOPLE

Waves Shape coastlines by erosion (cracks, caves, Storm waves and tsunamis can
arches, sea stacks, stumps) and deposition destroy coastal homes and lives
(beaches)

Tides Rise and fall of water twice a day; strong Help ships enter harbours, bring fish
tidal currents close to the shore, can generate
electricity

Currents Carry warm or cold water and change the Where warm and cold currents meet,
temperature of coasts waters are rich in nutrients and
become fishing grounds

So water movement shapes the land, controls coastal climate and supports marine life and
livelihoods, but it can also bring disasters.

Page 2 of 37

Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

− Explanation

Examples from the chapter:
Waves are called “coastal architects” (page 4). Hydraulic action and abrasion turn a
crack in a headland into a cave, then an arch, a sea stack and finally a stump (Fig. 1.4).
A tsunami’s run-up height can reach 30 metres or more (page 5).
Tides: the Gulf of Khambhat has a tidal range of about 12 metres. Ships check the water
depth and tidal range before berthing. India’s major tidal energy sites are the Gulf of
Kutch, the Gulf of Khambhat and the Sundarbans (page 7).
Currents: the warm Gulf Stream keeps the waters near Norway warm, so sea ice does
not form easily there even at 60°–70° latitude. The cold Labrador Current brings sea ice
and icebergs to lower latitudes off Canada (page 8).

Why: moving water carries energy (waves), volume (tides) and heat (currents).
Energy shapes coasts, volume changes depth, and heat changes climate.

Q3 Why are maritime zones important for a country?

Maritime zones are areas of the sea, measured from a country’s baseline and defined by
international law (UNCLOS). They tell everyone how far a country’s rights at sea go.
Territorial sea (up to 12 nautical miles): near-complete control, so the country can make
laws on customs, immigration and pollution and guard its coast.
Contiguous zone (up to 24 nautical miles): limited control to check smuggling, tax evasion
and illegal immigration.
Exclusive Economic Zone (up to 200 nautical miles): special rights over fish, oil and gas,
which give food, energy and jobs.
Maritime zones are important because they protect a country’s security, secure the resources
off its coast and prevent disputes, since every country follows the same agreed lines. Beyond
them lie the high seas, open to all.

− Explanation

Without agreed zones, every country could claim as much sea as it liked, and fishing
boats, oil companies and navies would clash. UNCLOS settles this by giving each coastal
country a fixed set of zones. It still keeps the sea open: foreign ships have the right of
innocent passage through the territorial sea and may sail peacefully through the EEZ
(pages 16–17).

Page 3 of 37

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Class 9 Social Science Chapter 10 Oceans and Life
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Why it matters for India: India has a coastline of 11,098.81 km (page 7) andcom
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Using ocean resources sustainably means using them today without destroying the ocean’s
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ability to provide them in the future. This is the idea of the Blue Economy: “the sustainable use
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Fig. 1.19 lists the key aims of SDG
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one of these aims.
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Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

Did you know? India stops most fishing along each coast for about two months
every year, during the main fish-breeding season (roughly April to July, at
different times on the east and west coasts). This gives fish stocks time to
recover.

Q5 How do early warning systems help protect people from tsunamis and cyclones?

Early warning systems detect cyclones and tsunamis, predict where and when they will strike,
and issue timely warnings so that people can evacuate and stay safe (page 9). For tsunamis
they work in four steps (Fig. 1.15):
1. Detection: seismic stations pick up undersea earthquakes in real time.
2. Confirmation: Ocean Bottom Pressure Recorders and tsunami buoys confirm that a tsunami
wave is passing.
3. Tracking: coastal tide gauges and radars follow the waves.
4. Warning dissemination: alerts go by satellite to government agencies and by SMS, email
and coastal display boards to officials and the public.
For cyclones, satellites and Cyclone Warning Services track storms, and INCOIS and IMD
forecast storm surges. The warning time lets people reach shelters, brings fishing boats back
to shore and readies rescue teams. This has greatly reduced the loss of human and animal lives
(page 10).

− Explanation

A tsunami crosses the deep ocean very fast, but it still takes time to reach a distant coast.
In 2004 the waves reached India’s east coast about two hours after the earthquake off
Sumatra. With no warning system in the Indian Ocean then, those two hours were lost.
Today the Indian Tsunami Early Warning Centre (ITEWC) sends alerts to the Government
of India, which informs state governments and emergency teams (page 14).
Other parts of the system described in the chapter:
NCRMP builds cyclone shelters, strengthens warning systems and improves
emergency response.
SSEWS (INCOIS with IMD) forecasts cyclone-induced storm surges and how far the
coast will be flooded.
GEMINI devices give fishermen at sea alerts about high waves, cyclones and tsunamis
in their own language.

Page 5 of 37

Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

Why technology is not enough: a warning only saves lives if people
understand it and act. That is why the chapter stresses public awareness and
training (page 14).

Did you know? Before Cyclone Phailin struck Odisha in October 2013, about 10
lakh people in Odisha and Andhra Pradesh were moved to safety, and far fewer
people died than in the 1999 Odisha super cyclone, which killed about 10,000
people.

LET’S EXPLORE — Page 3

Page 6 of 37

Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

Ocean Relief (looking at Fig. 1.2)
LET’S EXPLORE

Q1 Looking at Fig. 1.2: How do you think these oceanic features would have been formed?

Continent Continental Volcanic Submarine
Slope Island Canyon
Seamount
Abyssal Hill

Sea level

Continental Abyssal Rift Magma
Shelf Continental Plain Mid-Ocean Valley
Rise Ridge Trench

Fig. 1.2, page 2 — Submarine relief (redrawn, not to scale)

Most of these features were formed by the Earth’s internal forces (volcanic activity and
movement of plates) and by deposition and erosion of sediments:

Page 7 of 37

Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

FEATURE HOW IT WAS PROBABLY FORMED

Continental shelf The edge of a continent covered by the sea; sediments brought by rivers
make it shallow and gently sloping

Continental slope and The slope is the true edge of the continent; sediment sliding down it piles up
rise at its foot as the rise

Abyssal plain Fine sediments settling slowly for millions of years bury the uneven rock and
make the floor flat

Mid-ocean ridge and Plates move apart, magma rises, cools and builds a long volcanic range; the
rift valley crack along its crest is the rift valley

Seamount, volcanic Undersea volcanoes; one that grows above the sea surface becomes an
island island

Trench One plate bends down and sinks under another

Submarine canyon Cut into the shelf and slope by fast, sediment-laden underwater currents

− Explanation

Look at the red magma layer at the bottom of Fig. 1.2. It reaches up into the mid-ocean
ridge and the volcanic island. That is the book’s clue that these features are volcanic; the
box on page 3 says the mid-ocean ridge is “formed by volcanic activity” and that
seamounts are “often volcanic”.
Guyots are seamounts whose tops were flattened by wave action when they stood near
the surface, and which later sank below it (page 3).
Many submarine canyons continue the line of a river valley on land. Some were cut
when sea level was lower and the shelf was dry land.

Why “would have been”: nobody watched these features form; they took
millions of years. Scientists work out their origin from the rocks, sediments and
volcanic activity found there.

Link: you studied how internal and external forces shape the Earth’s surface in
Part I, Chapter 2. The same forces work under the sea.

Page 8 of 37

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Class 9 Social Science Chapter 10 Oceans and Life
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. com deep
Looking at Fig. 1.2 (shown with Q1 above): Which part of the ocean floor appears
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Shallow: the continental shelf along the edge of each continent. Coastal fish live on the shelf

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Q3 Looking at Fig. 1.2 (shown
would have an effect on marine life and ocean movements?
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Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

The shape of ocean basins and continents guides the direction of currents (page 8).
Ridges and seamounts bend deep currents.
Over the shallow shelf, waves slow down and grow taller before breaking; this is why
tsunamis rise so high at the shore.
Shallow, narrowing gulfs make tides higher, as in the Gulf of Khambhat (about 12 m).

− Explanation

Why: life in the sea depends on light and nutrients. Light is found only in the top
layer of water, so shallow places have the most life. Nutrients sink to the
bottom, so anything that pushes deep water up, such as a seamount or a ridge,
makes the surface water richer.

For movements, think of the sea floor as the bed of a river. A narrow, shallow bed makes
water rise and flow faster; a wide, deep bed lets it spread out. The same happens to
waves, tides and currents at sea.

Did you know? Coral reefs grow on shallow shelves in warm, clear tropical
seas. In India they are found in the Gulf of Mannar, the Gulf of Kutch,
Lakshadweep and the Andaman and Nicobar Islands.

LET’S EXPLORE — Page 5
Waves and the landforms they make
LET’S EXPLORE

Q1 Find out the names of some famous sea beaches in our country and locate them on the
map of India.

Some famous sea beaches of India, located on the map below:

Page 10 of 37

Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

1
10

9
2

8

Arabian Sea 3
4
Bay of Bengal
6
11
7

5

Famous sea beaches of India (positions from latitude and longitude)

Page 11 of 37

Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

NO. BEACH STATE / UT COAST

1 Shivrajpur Beach, near Dwarka Gujarat West

2 Juhu Beach, Mumbai Maharashtra West

3 Calangute Beach Goa West

4 Om Beach, Gokarna Karnataka West

5 Kovalam Beach, Thiruvananthapuram Keralam West

6 Marina Beach, Chennai Tamil Nadu East

7 Promenade Beach Puducherry (UT) East

8 Ramakrishna (RK) Beach, Visakhapatnam Andhra Pradesh East

9 Puri Beach Odisha East

10 Digha Beach West Bengal East

11 Radhanagar Beach, Swaraj Dweep (Havelock Andaman and Nicobar Islands Island
Island) (UT)

Beaches on the west coast face the Arabian Sea, those on the east coast face the Bay of
Bengal, and Radhanagar is on an island in the Andaman Sea.

− Explanation

How to locate a beach: find the city or town in an atlas index, note its latitude and
longitude, and mark the point on the coast. You can also use the School Bhuvan–NCERT
Geoportal mentioned on page 11.

Why there are so many beaches: a beach is a depositional landform. Waves
carry sand and pebbles along the coast and drop them where the water loses
energy, often in bays and along long, gently sloping coasts (page 4).

Did you know? Shivrajpur, Rushikonda (Visakhapatnam), Golden Beach (Puri)
and Radhanagar are among India’s Blue Flag beaches, an international label for
clean, safe and well-managed beaches.

Page 12 of 37

Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

Your own answer: add the beach nearest to your home, or other well-known
ones such as Kanyakumari (Tamil Nadu), Varkala (Keralam) or Diu.

In-text Questions — Pages 5–6
Tides (Fig. 1.5)

Q1 Observe Fig. 1.5 and note the change in water level during high and low tides. Do you
notice the oval layer around the Earth indicating water level? Can you also see how the
water level rises during high tide and falls during low tide?

Spring tide (full moon) Neap tide (first-quarter moon)

Earth

Sun Earth Moon Sun
Moon

Spring tide (new moon) Neap tide (third-quarter moon)
Moon

Earth

Sun Earth Sun

(a) (b)
Fig. 1.5, page 6 — (a) Spring tide (b) Neap tide (schematic diagram of tidal forcing showing
idealised bulges; redrawn)

Yes. The blue oval layer around the Earth is the ocean water. The pull of the Moon (and the
Sun) stretches it into two bulges: one on the side facing the Moon and one on the opposite
side.
Places under a bulge have a higher water level: high tide.
Places at the narrow sides of the oval, a quarter of the way round, have lower water: low
tide.

Page 13 of 37

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Class 9 Social Science Chapter 10 Oceans and Life
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As the Earth rotates, each place passes through both bulges and both narrow sides every
o m day,
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so most places get two high tides and two low tides a day.
In (a) the Sun, o
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and loweste m(spring tide). In (b) the Sun and Moon pull at right angles, so
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smaller

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− Explanation

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water levels at a coast: the gap between high
agl tide and smallest at neap tide.
water and low water is largest at spring

Why spring tides come at full moon and new moon: only on these daysmare the
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Sun, Earth and Moon in one line, so the pulls of the Sun and the Moon
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THINK ABOUT IT — Page 8 . a
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ag l Page 14 of 37

Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

Ocean Currents (Fig. 1.9)
THINK ABOUT IT

Q1 Observe the map carefully and note the movement patterns of cold and warm currents.
Do you think these currents affect the temperature of nearby coastal regions?

2
11 3
19 13
1
12
PACIFIC OCEAN ATLANTIC OCEAN 4 18 PACIFIC
14 5
6
15 23
16 7
8 22
17 10 20 INDIAN OCEAN 21
Cold current
Warm current 9
24

Fig. 1.9, page 9 — Major ocean currents (redrawn on a coastline map; numbers explained in
the key below; on a phone, swipe the map sideways)

KEY CURRENTS

Warm 1 Gulf Stream; 2 North Atlantic Drift; 5 North Equatorial Current (Atlantic); 6
currents Equatorial Counter Current (Atlantic); 7 South Equatorial Current (Atlantic); 8
(red Brazilian Current; 11 Alaska Current; 13 North Pacific Drift; 14 North Equatorial
arrows) Current (Pacific); 15 Equatorial Counter Current (Pacific); 16 South Equatorial
Current (Pacific); 18 Kuroshio Current; 20 Agulhas Current; 22 South Equatorial
Current (Indian); 23 Equatorial Counter Current (Indian)

Cold 3 Labrador Current; 4 Canaries Current; 9 Falkland Current; 10 Benguela
currents Current; 12 California Current; 17 Humboldt (Peru) Current; 19 Oyashio Current;
(blue 21 West Australian Current; 24 West Wind Drift
arrows)

Movement patterns
Warm currents (red) start near the Equator and flow towards the poles, mostly along the
eastern coasts of continents: Gulf Stream, Kuroshio, Brazilian and Agulhas Currents.
Cold currents (blue) flow from high latitudes towards the Equator, mostly along the western
coasts: California, Humboldt (Peru), Canaries, Benguela and West Australian Currents.
Together they form large loops, clockwise in the Northern Hemisphere and anticlockwise
in the Southern Hemisphere, because of the winds and the Coriolis force.

Page 15 of 37

Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

The cold West Wind Drift flows eastward all round Antarctica.
Yes, they affect coastal temperature. The warm Gulf Stream keeps the waters near Norway
warm, so sea ice does not form easily there even at 60°–70° latitude. The cold Labrador
Current brings sea ice and icebergs to lower latitudes off Canada (page 8).

− Explanation

Why: air takes on the temperature of the water it blows over. Winds blowing
from a warm current carry heat and moisture to the coast and make winters
milder. Winds from a cold current cool the coast and carry little moisture.

That is why some of the world’s driest deserts lie along coasts washed by cold currents:
the Atacama beside the Humboldt (Peru) Current and the Namib beside the Benguela
Current.

Did you know? Where warm and cold currents meet, the water is rich in
nutrients, so these places are major fishing grounds (page 9), for example near
Newfoundland (Gulf Stream and Labrador Current) and near Japan (Kuroshio
and Oyashio).

Tip for map work: trace each loop with your finger. In the North Atlantic: North
Equatorial Current westward → Gulf Stream northward → North Atlantic Drift
eastward → Canaries Current southward. That is one clockwise loop.

LET’S EXPLORE — Page 8

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Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

Ocean Currents around India (Fig. 1.9)
LET’S EXPLORE

Q1 Observe Fig. 1.9 and take a note on ocean currents along the coastline of India. What is
the nature of ocean currents?

Bay of
Bengal
Arabian
Sea

Equator
Eq. Counter Current

South Equatorial Current

West Australian C
INDIAN OCEAN

Cold current
Agulhas C West Wind Drift Warm current

Part of Fig. 1.9, page 9 — Ocean currents in the Indian Ocean (redrawn; on a phone, swipe
the map sideways)

Notes from the map
In the Arabian Sea, the current moves in a clockwise curve from the coast of Africa towards
the west coast of India and on towards Sri Lanka.
South of Sri Lanka, the current turns north-eastward into the Bay of Bengal.
Just north of the Equator a current flows westward; just south of it the Equatorial Counter
Current flows eastward, and further south the South Equatorial Current flows westward.
All the arrows near India are red; no cold current reaches India’s coast.
Nature: the currents along India’s coast are warm currents, because they come from the warm
tropical waters near the Equator. They are also seasonal: in the northern Indian Ocean the
currents follow the monsoon winds and reverse direction between summer and winter.

Page 17 of 37

Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

− Explanation

The map shows the summer pattern. In summer the south-west monsoon winds drive the
water clockwise. In winter the north-east monsoon winds push it the other way,
anticlockwise.

Why only here: the northern Indian Ocean is closed off by the land mass of
Asia to the north, and the monsoon winds over it reverse every season. In the
Atlantic and Pacific, the main currents keep roughly the same direction all year.

Did you know? The current along India’s west coast is called the West India
Coastal Current, and the one along the east coast is the East India Coastal
Current.

Link: warm seas around India supply moisture for monsoon rain, and cyclones
form over warm ocean waters (page 11). This is one reason the Bay of Bengal
sees frequent cyclones.

LET’S EXPLORE — Pages 9–10
Cyclones and Tsunamis — Early Warning Systems
LET’S EXPLORE

Q1 Most deaths during the 2004 Indian Ocean tsunami occurred in Indonesia. However,
the Island of Simeulue was largely spared from the disaster. Researchers suggest that
this was partly because of local folklore, passed down through generations, that
helped residents recognise the warning signs of a tsunami and respond quickly. Talk to
your elders and find out whether similar folk traditions or stories related to natural
disasters exist in your culture. Share these with your classmates and discuss how
traditional knowledge can help communities stay safe.

Sample findings (examples of such traditions, and what a coastal family’s elders might say):
On Simeulue, the story of smong (tsunami) says: if the ground shakes hard and the sea
runs back, run to the hills. People did exactly this in 2004.
After 2004, reports said that indigenous communities of the Andaman Islands, such as the
Onge, also reached higher ground in time, guided by knowledge passed down by their
elders.

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Class 9 Social Science Chapter 10 Oceans and Life
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Fishing elders watch for signs of a coming storm: a heavy swell on a calm day, seam
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flying inland, and a sudden change in the wind and the colour of the sky.
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How traditional knowledge helps:
agl
a s emact at once, without waiting for an official message.
agItlworks even when power, phones or the internet fail.
People

om
Stories, songs and sayings are easy to remember and pass on to children.
c
m. modern early warning systems. ag
se
It saves most lives when it works together with
la
− Explanation ag

.
On Simeulue, an earlier tsunami had killed many people. The survivors turned the
c omlesson
s e
into a story, told in lullabies and poems, so that every child grew up knowingm what to do.
m earthquake struck, people ran uphill without being gtold.
When theo2004
.c la a
se m
a
agl Why it works: a tsunami gives very little time near its source. In the few minutes
before the first wave, knowing what a shaking ground and a falling sea mean is
m a s
.co agl
worth more than any equipment.
s em
gla
Points for your class discussion:
a
Not every folk belief is reliable. Keep the ones that match science, such as “a sudden
fall of the sea means danger”.
. c om
m make people
Traditional knowledge and technology support each other. Elders’esigns
s
. comand official warnings tell them exactly where to go. agla
alert,

a sem Schools can help by recording such stories before they are forgotten.
agl
Your own answer: write down the actual stories or sayings your elders tell,
se m
c om landslides or drought, and say what
about floods, cyclones, earthquakes,
g l a
. a
em
warning sign each one teaches.
a s
agl

com
m .
THINKmABOUT IT — Page 14 la se
.co ag
a s em
agl c
m .
m a s e
. co agl
a sem
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Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

Making early warnings work
THINK ABOUT IT

Q1 If you receive a tsunami or cyclone alert on your phone right now, do you know the five
steps your family should take to stay safe?

Five steps for the family:
1. Stay calm and confirm. Check the alert on official sources (IMD, INCOIS, district
administration, radio or TV). Do not spread rumours.
2. Take the emergency kit: drinking water, dry food, medicines, torch, radio, charged phone
and important documents in a waterproof bag.
3. Move to safety as instructed. For a tsunami, go inland or to high ground at once, on foot if
roads are crowded. For a cyclone, go to the nearest cyclone shelter or stay in a strong
building away from windows.
4. Help others and secure the home. Take care of elders, children and persons with
disabilities; switch off electricity and gas; untie animals.
5. Stay safe until the all-clear. Do not go to the beach to watch. A tsunami comes in several
waves, and the calm eye of a cyclone is not its end.

− Explanation

The chapter says an early warning system saves lives only if people “know how to respond
appropriately” (page 14). These five steps are that response.
Plan before an alert comes: decide a family meeting point, learn the route to the
cyclone shelter or high ground, and keep the kit packed.
Natural warning signs: if you are at the coast and feel a strong earthquake, or see the
sea suddenly pull back, move to high ground without waiting for any message.

Why “stay calm and confirm” comes first: fake alerts cause panic, and panic
causes accidents. A minute spent checking a reliable source is not wasted.

Tip: 112 is India’s single emergency helpline number.

LET’S EXPLORE — Page 18

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Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

International Maritime Rules and Regulations
LET’S EXPLORE

Q1 Maritime disputes are conflicts or disagreements between countries over territory,
resources, or rights in naval areas such as oceans, seas, or coastal regions. Can you
find out some countries that have conflicts over their territorial sea waters?

Some countries with disputes over sea areas:

SEA AREA COUNTRIES WHAT THE DISAGREEMENT IS ABOUT

South China China, the Philippines, Vietnam, Small islands and reefs, fishing, oil and gas,
Sea Malaysia, Brunei and busy sea routes

East China Sea China and Japan A group of small islands and the waters
around them

Aegean Sea Greece and Turkey Width of territorial waters, islands and the
continental shelf

Palk Strait India and Sri Lanka Fishermen crossing into each other’s waters

Sir Creek, India and Pakistan A boundary in a tidal creek that also decides
Arabian Sea the sea boundary

Some disputes have been settled peacefully under UNCLOS: the India–Bangladesh sea
boundary in the Bay of Bengal was decided by an international tribunal in 2014.

− Explanation

Disputes arise because zones overlap. Two countries facing each other across a narrow
sea cannot both have 200 nautical miles of EEZ, and ownership of a tiny island can decide
who controls a large area of sea around it.
How such disputes can be settled: talks between the countries, or a case before an
international court or tribunal set up under UNCLOS. Bangladesh and Myanmar settled
their boundary in the Bay of Bengal this way in 2012.

Why it matters: the chapter says maritime rules exist to “help settle disputes
between countries” (page 18). Without them, such disagreements could turn
into conflict at sea.

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Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

Your own answer: disputes change over time. Check a recent atlas or news
report, and describe the sides fairly without taking one country’s claim as fact.

Questions and activities — Page 20
End of chapter
QUESTIONS AND ACTIVITIES

Q1 How do different features of the ocean floor affect human activities such as fishing,
transport, and underwater exploration?

Fishing: the shallow, sunlit continental shelf (about 0–200 m deep) is rich in nutrients and
marine life, so most fishing takes place there (pages 3 and 15). Seamounts and ridges attract
fish in the open sea. Deep abyssal plains and trenches have few fish.
Transport: ships need enough depth. Shallow areas such as the Singapore Strait force very
large tankers (VLCCs) to wait for high tide (page 7). Ports need deep water near the coast.
Seamounts and reefs are hazards, so ships rely on charts made by bathymetry. Undersea
cables must be laid along routes that avoid deep trenches and steep slopes.
Underwater exploration: the shelf is easiest to explore, so offshore oil and gas are drilled
there. Abyssal plains hold deep-sea minerals, but reaching them needs special technology.
Trenches such as the Mariana Trench are so deep, dark and high in pressure that very few
people have ever reached their floor.

− Explanation

FEATURE DEPTH MAIN EFFECT ON PEOPLE

Continental shelf Shallow Fishing, oil and gas, ports, coastal tourism

Continental slope Drops steeply Edge of most fishing; risk of underwater
landslides for cables

Abyssal plain Deep, flat Deep-sea minerals; cable routes

Mid-ocean ridge, Rise from deep Fish gather here; hazards to submarines
seamounts floor

Trench Deepest Hardest to explore; earthquakes and tsunamis
start near trenches

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Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

Did you know? Mumbai High, India’s largest offshore oil field, lies on the
continental shelf in the Arabian Sea, off the coast of Mumbai.

Why the shelf matters most: it is close to land, shallow enough to reach easily,
and has the most life. That is why the chapter calls it “rich in marine life and
resources like oil and gas”.

Q2 How do waves, tides, and ocean currents influence climate, marine life, and human
activities around the world?

CLIMATE MARINE LIFE HUMAN ACTIVITIES

Waves Mix the surface water with air, Shape coasts and Beaches for tourism; storm
spreading heat build beaches waves and tsunamis destroy
where many coastal property
creatures live

Tides Mix coastal waters twice a Fish move close to Help ships enter harbours;
day shore at high tide better catch for fishermen; tidal
energy (Gulf of Kutch, Gulf of
Khambhat, Sundarbans)

Currents Warm or cool coastal regions: Where warm and Rich fishing grounds; help or
the Gulf Stream keeps waters cold currents meet, slow ships; affect rainfall and
near Norway warm; the waters are rich in farming on coasts
Labrador Current brings nutrients
icebergs

So these three movements spread heat, feed marine life and support trade, fishing and energy,
but they can also bring disasters.

− Explanation

Of the three, currents have the biggest effect on climate because they carry huge amounts
of heat over thousands of kilometres. Without the Gulf Stream, north-western Europe
would be much colder in winter.
Tides matter most for ports. Tidal ranges in some ports reach 4–5 metres, and in the Gulf
of Khambhat about 12 metres. A ship must check both the water depth and the tidal range
before berthing (page 7). Tidal currents can reach 5–6 knots (about 9–11 km/h).

Page 23 of 37

ase
Class 9 Social Science Chapter 10 Oceans and Life
ag l AglaSem · NCERT Solutions

m
.co
Waves are the main shapers of coastlines: cracks become sea caves, then arches, sea

em
stacks and stumps (Fig. 1.4).
m a s
. o
ctip: a gl in an exam
a s em
Writing a table like this is a quick way to cover 3 × 3 = 9 links
agl
answer. Add one example from the book in each row.

co m
m . ag
la se
Q3 g resources.
Describe the importance ofamarine

co m
e m.

om l asintrinsic
c g
Marine resources are the materials and features of the oceans that have or economic
value. m . are of two kinds: living (fish, marine organisms, aquaticaplants) and non-living
e
las and energy). They are important for:
They

ag
(minerals
Food and livelihood: fish are a major source of protein; fishing and aquaculture give work to
m a s
c o agl
millions.
m .
s e
Energy: offshore oil and gas, and renewable “blue energy” from tides, waves and offshore
wind.
a gla
Minerals and materials: sand, gravel and deep-sea minerals.

com
Trade and tourism: about 90% of world trade by volume is carried by sea; coastal tourism
.
em of plants and
is a huge industry.
m as
co gl
Environment: coral reefs and other ecosystems support a great variety
. a
em
animals.
la s
ag Culture: the sacred śhaṅkha (conch) and kapardikā (cowrie shells, once used as money)
are linked to the Samudra Manthana story.
se m
c o m they are the bedrock of local economies, so they
For a country with a long coastline like India,
g l a
must be used without harming marine .ecosystems. a
a sem
ag l
− Explanation

Fig. 1.17 (page 15) classifies marine resources:
co m
m .
om l a se fish beyond the
Living: fish (coastal or neritic fish on the shelf at 0–200 m; oceanic

em ag bio-organisms,
.c shelf at more than 200 m), bioactive natural products, marine
a s
agl
submerged aquatic vegetation.

c
Non-living: minerals; energy, which is conventional (oil, natural gas) or non-
m .
conventional (biofuels, gas hydrates, offshore wind, ocean energy such as tidal, wave
and current energy, and OTEC).om a s e
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Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

Why “sustainably”: fish stocks, coral reefs and clean water can be used up or
damaged. The Blue Economy idea (page 16) is to gain economic growth and
jobs while keeping the ocean healthy.

Q4 Draw a poster that encourages people to protect marine resources. Include a slogan
(like Save Our Seas or Fish for the Future) and explain your message in 2–3 sentences.

Sample poster

Page 25 of 37

Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

SAVE OUR SEAS
Healthy oceans, healthy lives

No plastic in the sea · Catch only what
the sea can replace · Protect coral reefs
The ocean feeds us, gives us work and
keeps our climate steady. Let us keep it alive.

A sample poster: slogan, one strong picture and three actions

Message (2–3 sentences): Our seas give us food, jobs, energy and a steady climate, but
plastic, oil spills and overfishing are killing marine life. If we keep plastic out of the sea, catch
only as many fish as the sea can replace, and protect coral reefs and mangroves, the ocean will
keep supporting us. Save Our Seas, for us and for the generations to come.

Page 26 of 37

Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

− Explanation

How to make a good poster:
Keep the slogan short and large, at the top, so it can be read from far away.
Use one strong picture rather than many small ones.
Give two or three clear actions that people can actually take.
Use sea colours (blues and greens) with one bright warning colour such as red.
Other slogans you could use: “Fish for the Future”, “No Plastic, More Fish”, “Blue Ocean,
Bright Future”, “Clean Coasts, Healthy Seas”.

Why these actions: they match the SDG 14 aims in Fig. 1.19: reduce marine
pollution, regulate fishing and conserve marine areas.

Page 27 of 37

Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

Q5 Using a map of India, mark at least five coastal states that might need tsunami
warnings.

6 5

4

7

2
Arabian Sea
Bay of Bengal

P A

1
3

Coastal states and Union Territories of India that need tsunami warnings

States marked: 1 Tamil Nadu, 2 Andhra Pradesh, 3 Keralam, 4 Odisha, 5 West Bengal. Also 6
Gujarat and 7 Maharashtra on the west coast, and the Union Territories A Andaman and
Nicobar Islands and P Puducherry.

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Class 9 Social Science Chapter 10 Oceans and Life
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o
Reason: the east and south coasts face the earthquake zone near the Andaman Islandsmand
m .c and
e
Sumatra. In 2004, Tamil Nadu, Puducherry, Andhra Pradesh, Keralam and the Andaman
Nicobar Islands m
co
suffered the most damage (page 12).
. las ag
e m
ag las
− Explanation

Tsunamis are set off mostly by large undersea earthquakes where one plate sinks under
another. Two such zones threaten India: om
.c ag
m
seand Nicobar Islands to Sumatra, which caused the
2004 tsunami and threatens a l
the zone running past the Andaman
a
g whole east coast and the islands;
the
the Makran coast (off Pakistan and Iran) in the Arabian Sea, which can send waves to
Gujarat and Maharashtra, as happened in 1945.
.c om
e
sthem
om was hit in 2004: although it is on the west coast,
Why.cKeralam gl a
a
em Sri Lanka and the southern tip of India and struck its coast.
waves bent

la saround
ag
omLakshadweep islands are also on the
Map tip: mark the states on the coast itself, number them, and write the key
a s
below the map. Goa, Karnataka and.cthe
em warning system. agl
coast and are covered by theasnational
agl

co m
m .
se
om in a group and act out what would happen when a acyclone
Q6 .cWork gla warning is issued.
a s em Highlight what role different people, like scientists, officials, and coastal villagers,
agl would play.

se m
com g l a
. a

e m
las
Sample role-play plan
ag

co m
m .
m la se
.co ag
a s em
agl c
m .
m a s e
. co agl
a sem
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Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

ROLE WHAT THEY DO AFTER THE WARNING

Scientists (IMD, INCOIS) Track the cyclone by satellite and radar; forecast its path, landfall
time, wind speed and storm surge; issue warnings

Officials (District Collector, Open cyclone shelters, order evacuation, close schools, stock
disaster management) food, water and medicines, keep rescue teams ready

Fisheries department, Coast Stop fishing; call boats back to shore; send alerts to fishermen
Guard through GEMINI

Panchayat members, Go house to house, announce on loudspeakers, help elders and
volunteers the disabled reach shelters

Coastal villagers Pull boats ashore, tie down nets and roofs, pack emergency kits,
move with their animals to shelters

Radio, TV, teachers Spread correct information and stop rumours

The play shows that a warning saves lives only when everyone plays their part quickly.

− Explanation

A sample script in four scenes
1. Weather office: scientists see a cyclone forming over the warm Bay of Bengal and
send an alert two days ahead.
2. Collector’s office: officials meet, decide which villages to evacuate, and open shelters
built under NCRMP.
3. Fishing village: a fisherman at sea gets the alert on his phone through GEMINI and
returns. Volunteers go door to door; an old woman does not want to leave her home
and is gently persuaded.
4. Cyclone shelter: families wait safely as the storm passes. Next morning, after the all-
clear, officials check damage and begin relief.

Did you know? IMD issues cyclone warnings in stages, from a pre-cyclone
watch about three days before landfall to a cyclone alert and then a cyclone
warning as it comes closer.

Why act it out: the chapter says public awareness and training are as important
as technology (page 14). Practising roles helps people remember what to do in
a real emergency.

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Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

Q7 Suppose a foreign ship is sailing through India’s territorial sea. What principle allows
the ship to pass through these waters, subject to certain conditions?

The principle of Innocent Passage.
It allows foreign ships to pass through a country’s territorial sea as long as they do not
threaten its peace, good order or security. The conditions are:
The ship must move continuously, without stopping, except in emergencies or breakdowns.
It must not fish, carry out military operations or do anything else that is not peaceful.
It must obey India’s laws in the zone, such as those on customs, immigration and pollution.
So the ship may pass, but it may not use India’s territorial sea for its own purposes.

− Explanation

India has near-complete control over its territorial sea (up to 12 nautical miles from the
baseline), but this control is “subject to the right of innocent passage for foreign ships”
(page 16). The principle balances two needs: a country’s security, and the freedom of
ships to travel across the world’s seas.

Did you know? Under UNCLOS, a foreign submarine passing through another
country’s territorial sea must travel on the surface and show its flag.

Common mistake: innocent passage is not the same as the freedom of
navigation on the high seas. On the high seas all countries have equal rights; in
the territorial sea a foreign ship is only a guest passing through.

Q8 A country has an Exclusive Economic Zone (EEZ) extending up to 200 nautical miles
from its baseline. What rights does the country have over the natural resources in this
zone?

In its EEZ, the country has special rights to explore, use and manage the natural resources of
the water, the sea bed and the ground beneath it:
Living resources: fish and other marine life; it decides who may fish and how much.
Non-living resources: oil, natural gas and minerals.
Energy from tides, waves, currents and winds, and the right to build rigs and other
structures for these uses.

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Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

The duty to conserve these resources and protect the marine environment.
However, the country does not fully own or control the waters of the EEZ: ships of other
countries may still pass through peacefully (page 17).

Baseline Contiguous zone (12–24 NM)

High
Land Exclusive Economic Zone (EEZ) seas
from the baseline up to 200 NM

0 12 24 200
Territorial sea (0–12 NM) Distances in nautical miles (NM), to scale

Maritime zones measured from the baseline, drawn to scale

− Explanation

The EEZ is defined under UNCLOS. Its rights are about resources, not full ownership. That
is the key difference from the territorial sea.

1 nautical mile = 1,852 m = 1.852 km
12 NM = 12 × 1.852 = 22.224 km (territorial sea)
24 NM = 24 × 1.852 = 44.448 km (contiguous zone limit)

200 NM = 200 × 1.852 = 370.4 km (EEZ limit)

Why it matters: about 370 km of sea along the whole coast, plus the waters
around the islands, is a huge storehouse of fish, oil and gas for a coastal
country like India.

Did you know? Other countries keep some freedoms in the EEZ, such as flying
over it and laying undersea cables and pipelines.

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Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

Q9 Create a model of an ocean with ship routes, protected zones, and safety measures.
Based on the model, explain how it follows maritime laws and protects the ocean.

Method: on a board or tray, paint the land and sea; mark the baseline and the 12, 24 and 200
nautical mile lines with string; add ship routes, protected zones and safety features with clay,
paper and toothpick flags.

Baseline 12 NM 24 NM 200 NM

Shipping lane (inbound)
Separation zone

Shipping lane (outbound)
Lighthouse
Port
Marker buoys

Fishing zone
Waste
collection (seasonal limits)
LAND
Marine protected Tsunami
area (coral reef) buoy

Oil rig + safety zone

Territorial Contiguous
sea zone Exclusive Economic Zone High seas

Sample plan of the model (top view; zone widths not to scale)

How the model follows maritime laws and protects the ocean:
Maritime zones (UNCLOS) show where the country has control and where the high seas
begin.
Separate inbound and outbound shipping lanes with lighthouses and buoys follow
COLREGs and prevent collisions.
Marine protected area around the coral reef, closed to ships and fishing, conserves marine
life (SDG 14).
Fishing zone with seasonal limits regulates fishing and prevents overfishing.
Oil rig with a safety zone in the EEZ uses the country’s resource rights safely.
Tsunami buoy is part of the early warning system; a waste collection point at the port
stops ships from dumping waste at sea (MARPOL).

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Class 9 Social Science Chapter 10 Oceans and Life
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co m
m.
− Explanation

m
Materials: a othick l asepaper,
.csmall toy boats or paper boats. g
cardboard sheet or tray, blue and brown paint, clay, string,
m a
se
toothpicks,
g la
aSteps:
1. Paint the land on one side and the sea on the rest.
2. Mark the baseline along the coast and lay o m for the zone limits. Label each one.
. c strings
emarrows in opposite directions and a gap between ag
a
3. Make two parallel shipping lanes withs
them.
agl
4. Place a lighthouse at the harbour entrance and red and green buoys along the channel.
5. Mark the coral reef with green clay and fence it off as a protected area.
. c om
6. Add a fishing zone, an oil rig with a circle around it, and a tsunami buoymfar out at sea.
m l ase
m .co ag
a se
Why each part is there: every feature answers one rule from the chapter: zones
ag l (UNCLOS), traffic rules at sea (COLREGs), no pollution from ships (MARPOL),
and conservation (SDG 14). When you present, point to each feature and name
om a s
.c agl
the rule it follows.

a s em
agsol the zones need not be drawn to scale. On a real
Note: the model is a plan,
chart the 200 NM line would be about 17 times as far from the baseline as the 12
NM line (200 ÷ 12 ≈ 16.7). com .
m
com ase
. agl
a se m
agl
sem
com g l a
Chapter at a glance m . a
e
as is the set of landforms on the sea floor: continental shelf,
a g l
Ocean relief (submarine relief)
continental slope, continental rise, abyssal plain, mid-ocean ridge, seamounts and guyots,

com
and trenches. The Mariana Trench is the deepest place on Earth; the Mid-Ocean Ridge is
the longest mountain range. .
m → sea cave → arch
m a s e(crack
c→o sea stack → stump) and deposition (beaches). Tsunamis glare giant waves caused mainly
Waves are mainly caused by winds and shape coasts by erosion
. a
a s em by undersea earthquakes; their run-up height can reach 30 m or more.
agl Tides rise and fall twice a day. Spring tides (full moon and new moon; Sun, Earth and
m .c
m
Moon in line) have the greatest range; neap tides (first- and third-quarter moon) have the
o l a se
c
smallest. Tides help navigation,.fishing and tidal energy (Gulf of Kutch, Gulf of Khambhat,
a g
se m
l a
Sundarbans). The Gulf of Khambhat has a range of about 12 m.
g by winds, the Coriolis force, differences in temperature and
Ocean currents are acaused
salinity, and the shape of continents and basins. Warm currents (red on maps) and cold
co m
m .
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.co

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Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

currents (blue) change coastal climate: the Gulf Stream keeps Norway’s waters warm; the
Labrador Current carries icebergs. Where they meet, fishing grounds form.
Early warning systems detect, confirm, track and announce cyclones and tsunamis. India
has NCRMP, SSEWS (INCOIS with IMD), ITEWC with tsunami buoys, and GEMINI devices
for fishermen. Public awareness is as important as technology.
Marine resources are living (fish, bio-organisms, aquatic vegetation) or non-living
(minerals, energy). They give food, livelihoods, energy, trade (about 90% of world trade by
volume goes by sea), tourism and cultural value, and must be used sustainably: the Blue
Economy and SDG 14: Life Below Water.
Maritime zones under UNCLOS are measured from the baseline: territorial sea up to 12 NM
(near-complete control, with innocent passage), contiguous zone up to 24 NM, EEZ up to
200 NM (resource rights). Beyond lie the high seas (about 64% of the oceans), a global
commons. 1 NM = 1,852 m.
Maritime rules such as COLREGs (rules of the road at sea) and MARPOL (no pollution from
ships) keep the seas safe, clean and open, and help settle disputes peacefully.

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Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

Quick revision
TERM WHAT IT MEANS WHERE IT WHAT THE CHAPTER SAYS
APPEARS IN THE ABOUT IT
CHAPTER

Continental shelf Submerged, shallow edge Ocean Relief, pages Rich in marine life and in resources
of a continent 2–3 (Fig. 1.2) like oil and gas

Mid-ocean ridge Huge underwater Ocean Relief, pages Formed by volcanic activity; the
mountain range 2–3 world’s longest mountain range

Trench Deepest part of the ocean Ocean Relief, pages The Mariana Trench (Pacific) is the
floor 2–3 deepest place on Earth

Wave Alternate rise and fall of Waves, pages 4–5 Caused mainly by winds; ‘coastal
the sea surface (Figs. 1.3, 1.4) architects’ that make caves, arches,
stacks, stumps and beaches

Tsunami Giant wave caused mainly Pages 5, 9 and 12 Run-up height up to 30 m or more;
by an undersea the 2004 Indian Ocean tsunami killed
earthquake about 2,30,000 people

Spring tide / Tides with the largest / Tides, pages 5–7 Spring tides at full and new moon;
neap tide smallest range (Figs. 1.5, 1.6) neap tides at first- and third-quarter
moon

Ocean current Continuous stream of Ocean Currents, Warm currents shown in red, cold in
water flowing in a pages 8–9 (Fig. 1.9) blue; Gulf Stream and Labrador
definite direction Current as examples

Coriolis force Force from Earth’s Margin note, page 8 To the right in the Northern
rotation that deflects Hemisphere, to the left in the
moving objects Southern

Early warning System to detect hazards Pages 9–14 (Figs. Detection → confirmation → tracking
system and warn people in time 1.15, 1.16) → warning dissemination; ITEWC,
SSEWS, NCRMP, GEMINI

Marine resources Ocean materials and Pages 14–15 (Figs. Living and non-living; food, energy,
features with intrinsic or 1.17, 1.18) minerals, trade, tourism, culture
economic value

Blue Economy Sustainable use of ocean Don’t Miss Out, World Bank definition; linked to SDG
resources for growth and page 16 (Fig. 1.19) 14: Life Below Water
jobs

Territorial sea / Sea up to 12 NM under Maritime Zones, Foreign ships may pass if they do not
innocent near-complete national pages 16–17 (Fig. threaten peace, good order or

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Class 9 Social Science Chapter 10 Oceans and Life AglaSem · NCERT Solutions

TERM WHAT IT MEANS WHERE IT WHAT THE CHAPTER SAYS
APPEARS IN THE ABOUT IT
CHAPTER
passage control 1.20) security

Exclusive Zone up to 200 NM from Page 17 Special rights over fish, oil and gas,
Economic Zone the baseline but not full ownership of the waters

High seas International waters Pages 17–18 About 64% of the oceans; global
beyond all EEZs commons; laws of the flag state
apply on ships

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