Land And Oceans

Class 6 | Social Science — Geography | Unit 2

Class 6 Unit 2 Geography

Unit 2 Land and Oceans

Learning Objectives

To understand the continents and oceans. To learn about the characteristic features of different landforms and oceans. To know about the classification of landforms. To understand the oceans and its features.

This lesson focuses on the land and oceans found on Earth. It deals with the classification of landforms - first, second and third order landforms.

The teacher enters the classroom with giant-sized envelopes. The students are enthusiastic to know about the content of the envelopes. The teacher asks the children to sit in groups and explains the activity. Each group is given an envelope which contains seven jig-saws and a chart paper. The teacher asks them to paste the jig-saws (continents) close to each other leaving no gap between them. The teacher asks them to colour the remaining places in blue. A group pastes the continents and comes first with the chart without any gaps in between the continents. The teacher then puts the chart on the board and the children applaud.

"What kind of picture is this? Once I have seen one like this in the atlas, " says Yazhini.

"You are right. This is Pangea, the Super Continent, and the Sea around is Panthalasa. It was 200 million years ago, when these landmasses moved away from each other to gain the present position as continents and oceans." says the teacher.

"What makes it to move madam?" asks Nila.

"Nothing other than the internal heat of the Earth," says the teacher and continues, "this lesson deals about the continents and oceans in detail".

The Earth is covered by water which occupies 71 percent and land that occupies 29 percent of the Earth's surface. The surface of the Earth is not even, because it has lofty mountains, deep oceans and other landforms. These landforms can be classified as:

Classification of landforms

1. First order landforms

Continents and oceans are grouped as first order landforms. The vast land masses on Earth are called Continents and huge water bodies are called Oceans. There are seven continents. They are Asia, Africa, North America, South America, Antarctica, Europe and Australia. Asia is the largest continent, whereas Australia is the smallest one.

GEO CONNECT: Land classification - Sangam period

1. kurinji mountain and its environs.

2. Mullai Forest and its surroundings.

3. Marutham agricultural lands and its adjoining areas.

4. Neithal sea and its environs

5. Palai Desert region

Which of the above landform category do you belong to?

Apart from continents, there are five oceans located on the Earth's surface. They are the Pacific, Atlantic, Indian, Southern and Arctic Oceans. Among these oceans, the Pacific Ocean is the largest and the Arctic Ocean is the smallest.

Activity

Required materials

• A circular plate
• 7 slices of a carrot
• A glass of water

Procedure

• Write the abbreviations A s, A F, N A, S A, A n, E u and A u on each slice in descending order of its size.
• The teacher hangs a wall map of the world.
• The students have the expansion of each abbreviation written on the board.
• Students now try to place the slices on the plate matching the position of the continents in the world map.
• They pour some water.
• The teacher shows the oceans in the world map.
• Accordingly, the students put their fingers in the respective places and repeat the names of the ocean stirring the water.
• The students learn the position, comparative size of the continent and the position of oceans.

Do you Know

Isthmus: A narrow strip of land which connects two large landmasses or separate two large water bodies.

2. Second order landforms

The second order landforms are categorised as mountains, plateaus and plains.

2.1 Mountains

A landform that rises 600 metre above its surroundings and has steep slopes is called a mountain. Mountains are found in isolation or in groups. If the mountains extend for a larger area continuously, it is called a mountain range. These ranges stretch for hundreds or thousands of kilometres. The Himalayas of Asia, the Rocky Mountains of North America and the Andes of South America are such examples. The Andes Mountain in South America is the longest mountain range (7,000 km) in the world. The highest point of a mountain is known as its peak. Mount Everest is the highest peak (8,848 metre) in the world.

Which country is Mount Everest located in?

HOTS

December 11 – International Mountain Day

Prepare slogans, posters and placards to celebrate International Mountain Day.

Activity Complete the given table with the help of an atlas. Follow the example.

Serial Number	Mountain Ranges	Peaks	Continents	Elevation (metres)
1	The Himalayas	Everest	Asia	8,848 metre
2	The Rockies
3	The Andes
4	The Alps
5	The Eastern Ghats

HOTS

You know the importance of conservation of forests. Do you think conservation of mountains is also equally important?

Mountains are the sources of rivers. They provide shelter to flora and fauna. Here, tourism is an important activity. During summer, people go to mountain regions to enjoy the pleasing cool weather. Udhagamandalam, Kodaikanal, Kolli hills, Yercaud and Yelagiri are some of the hill stations found in Tamil Nadu.

2.2 Plateaus

Plateaus are the elevated portions of the Earth that have flat surfaces bounded by steep slopes. The elevation of plateaus may be a few hundred or several thousand metres. Tibetan Plateau is the highest plateau in the world. So, it is called as the 'Roof of the world'. The flat-topped part of the plateau is called Tableland. The plateaus are generally rich in minerals. The Chotanagpur Plateau is one of the mineral rich plateaus in India. Therefore, mining is one of the major activities of the people living here. The Deccan Plateau in peninsular India is of volcanic origin.

Do you know

Dharmapuri plateau, Coimbatore plateau and Madurai plateau are found in Tamil Nadu.

2.3 Plains

Plains are flat and relatively low-lying lands. Plains are usually less than 200 metre above sea level. Sometimes they may be rolling or undulating. Most plains are formed by rivers and their tributaries and distributaries. These plains are used extensively for agriculture due to the availability of water and fertile soil.

Do you Know

The plains have been the cradle of civilisations from the earliest times. For example: the Indus in India, the Nile valley in Egypt is some of the early civilisations which developed and flourished. They are most suitable for human inhabitation. Hence, they are the highly populated regions of the world. The oldest civilisations like the Mesopotamian and the Indus civilisations developed in river plains. The Indo-Gangetic plain in North India is one of the largest plains in the world. The plains formed by river Cauvery and Vaigai are important plains found in Tamil Nadu. Coastal plains are the low-lying lands adjacent to oceans and seas.

Activity Complete the given table with the help of an atlas. Follow the example.

Serial Number	Continents	Plateaus	Plains
1	Asia	Tibetan Plateau	Yangtze Plain
2	North America
3	South America
4	Australia
5	Europe
6	Africa

Activity

Make a model of different landforms. Prepare an album of people's activities in different landforms.

3. Third order landforms

Third order landforms are formed on mountains, plateaus and plains mainly by erosional and depositional activities of rivers, glaciers, winds and waves. Valleys, beaches and sand dunes are some examples of third order landforms. Erosion is the process of removal of surface material from the Earth's crust. The eroded materials are transported and deposited on the low-lying areas. This process is called as Deposition.

HOTS

When you are walking on the Marina beach in Chennai, which order of landform are you on?

4. Oceans

The Earth looks blue when we see it from space. This is because, two-thirds of it is covered by water. The water is found in oceans and seas. Oceans are vast expanse of water. Seas are water bodies partially or fully enclosed by land. As you have studied previously, there are five main oceans in the world.

4.1 The Pacific Ocean

The Pacific Ocean is the largest and deepest ocean on the Earth. It covers about one-third of the Earth's total area and spreads for about 168.72 million square kilo metre. It is bounded by Asia and Australia in its west and North America and South America in its east. It stretches from the Arctic Ocean in the north to the Southern Ocean in the south.

Do you know

If Mount Everest, which is the highest peak (8,848 metres) was placed into the Mariana Trench, still there would be 2,146 metres of water left. The depth in metres from the Mean Sea Level is denoted as metre power minus.

This ocean's shape is roughly triangular with its apex in the north at the Bering Strait which connects the Pacific Ocean with the Arctic Ocean. The Bering Sea, the China Sea, the Sea of Japan, Tasman Sea and the Philippine Sea are some of the marginal seas of the Pacific Ocean. Indonesia, Philippines, Japan, Hawaii, New Zealand are some of the islands located in this Ocean. The deepest point Mariana Trench is 10,994 m- and is located in the Pacific Ocean. A chain of volcanoes is located around the Pacific Ocean called the Pacific Ring of Fire.

Do you know

The Spanish navigator Ferdinand Magellan named the ocean Pacific, meaning calm or tranquil.

4.2 The Atlantic Ocean

The Atlantic Ocean is the second largest ocean on Earth. It covers one sixth of the Earth's total area and spreads for about 85.13 million square kilo metre. It is bounded by North America and South America in the west and Europe and Africa in the east. Like the Pacific, it stretches from the Arctic Ocean in the north to the Southern Ocean in the south. The shape of the Atlantic Ocean resembles the letter 'S'. The Strait of Gibraltar connects the Atlantic Ocean with the Mediterranean Sea. The Atlantic Ocean is the busiest shipping route between the Eastern and Western hemispheres. The deepest point is the Milwaukee Deep in the Puerto Rica Trench. It has a depth of about 8600 m-. The Caribbean Sea, the Gulf of Mexico, the North Sea, the Gulf of Guinea and the Mediterranean Sea are important marginal seas of the Atlantic Ocean. St. Helena, Newfoundland, Iceland and Falkland are some of the islands found in this ocean.

HOTS

Why are the Red Sea, Dead Sea and Black Sea named so?

4.3 The Indian Ocean

The Indian Ocean is the third largest ocean on the Earth's surface. It covers an area of about 70.56 million square kilo metre. It is named after India. It is triangular in shape and bounded by Africa in the west, Asia in the north and Australia in the east. The Andaman and Nicobar Islands, Lakshadweep, Maldives, Sri Lanka, Mauritius and the Reunion Islands are some of the islands located in the Indian Ocean. Malacca strait connects the Indian Ocean and the Pacific Ocean. Palk Strait connects the Bay of Bengal and Palk Bay. The Bay of Bengal, the Arabian Sea, the Persian Gulf and the Red Sea are some of the important marginal seas of the Indian Ocean. The Java trench (7,725 metre minus) is the deepest point in the Indian Ocean.

Do you know

6° Channel separates Indira Point and Indonesia
8° Channel separates Maldives and Minicoy islands
9° Channel separates Lakshadweep Islands and Minicoy islands
10° Channel separates Andaman and Nicobar Islands.

4.4 The Southern Ocean

The Southern Ocean surrounds the continent of Antarctica and is enclosed by the 60°S latitude. It covers an area of 21.96 million square kilo metre. It is bordered by the southern parts of the Pacific, the Atlantic and the Indian Oceans. The Ross Sea, the Weddell Sea and the Davis Sea are the marginal seas of this Ocean. Farewell Island, Bowman Island and Hearst Island are some of the islands located in this ocean. The water in this ocean is very cold. Much of it is covered by sea ice. The deepest point in this ocean is South Sandwich Trench with a depth of 7,235 metre power minus.

HOTS

When you travel from Japan to California, which ocean would you travel across?

4.5 The Arctic Ocean

The Arctic Ocean is the smallest ocean. It covers an area of 15.56 million square kilo metre. It lies within the Arctic Circle. It remains frozen for most of the year. The Norwegian Sea, the Greenland Sea, the East Siberian Sea and the Barents Sea are some of the marginal seas of this ocean. Greenland, New Siberian Island and Novaya Zemlya Island are some of the islands located in the Arctic Ocean. The North Pole is situated in the middle of the Arctic Ocean. The Eurasian Basin is the deepest point in the Arctic Ocean, which is about 5,449 m- in depth.

Activity Complete the given table with the help of an atlas. Follow the example.

Serial number	Name of the Ocean	Area (million Square kilo metre)	Trenches	Depth (metre)
1	Pacific Ocean	168.72	Marina	10,994
2	Atlantic Ocean
3	Indian Ocean
4	Southern Ocean
5	Artic Ocean

HOTS

When you arrange the continents in ascending order according to their size, which ranks third?

Summary

The surface of the Earth is covered by 71 percent of water and 29 percent of land. The landforms are classified as first order, second order and third order landforms. Continents and oceans are the first order landforms. There are seven continents and five oceans on the Earth's surface. Mountains, plateaus and plains are the second order landforms. Valleys, beaches and sand dunes are the third order landforms. Many islands and marginal seas are found in the oceans.

Glossary

Island - A land surrounded by water on all sides. Bay - A broad inlet of the sea where the land curves inwards. Strait - A narrow stretch of water linking two large water bodies. Trench - The deepest part of the ocean. Peninsula - The land surrounded by water on three sides.

Exercises

Exercise A. Choose the correct answer

1. Which of the following is the smallest ocean on Earth?

a. The Pacific Ocean b. The Indian Ocean c. The Atlantic Ocean d. The Arctic Ocean

2. The Malacca Strait connects

a. The Pacific and Atlantic Oceans b. The Pacific and Southern Oceans c. The Pacific and Indian Oceans d. The Pacific and Arctic Oceans

3. Which of the following oceans is the busiest ocean?

a. The Pacific Ocean b. The Atlantic Ocean c. The Indian Ocean d. The Arctic Ocean

4. The frozen continent is

a. North America b. Australia c. Antarctica d. Asia

5. A narrow strip of water that connects two large water bodies

a. A Strait b. An Isthmus c. An Island d. A Trench Exercise B. Fill in the blanks

1. The world's largest continent is

2. is the mineral rich plateau in India.

3. The largest ocean is

4. Deltas are order landforms.

5. The Island continent is .

Exercise C. Circle the odd one out

1. Africa, Europe, Australia, Sri Lanka

2. The Arctic Ocean, the Mediterranean Sea, the Indian Ocean, the Atlantic Ocean

3. Plateau, Valley, Plain, Mountain

4. The Bay of Bengal, the Bering Sea, the China Sea, the Tasman Sea.

5. The Andes, the Rockies, the Everest, the Himalayas.

Exercise D. Match the following

A	B
1. The South Sandwich Trench
2. The Milwaukee Trench
3. The Mariana Trench
4. The Eurasian basin
5. The Java Trench

Options: a) The Atlantic Ocean b) The Southern Ocean c) The Indian Ocean d) The Pacific Ocean e) The Arctic Ocean

Exercise E.

1) Consider the following statements

1. Plains are formed by rivers.
2. The 'South Sandwich Trench' is found in the Indian Ocean.
3. Plateaus have steep slopes.

Choose the correct answer using the codes given below.

a. 1 and 3 b. 2 and 3 c. 1, 2 and 3 d. 2 only

ii) Which of the following statement (s) is/are true?

Statement 1: Mountains are second order landforms.
Statement II: The Mariana Trench is the deepest trench in the world.

a. 1 is true; II is wrong b. 1 is wrong; II is true c. Both the statements are true d. Statements 1 and II are wrong. Exercise F. Answer in a word

1. Which is the highest plateau in the world?

2. Name a second order landform.

3. Which Ocean is named after a country?

4. Name the island located in the Arabian Sea.

5. What is the deepest part of the ocean called as?

Exercise G. Answer in brief

1. What is a continent?

2. Name the continents which surround the Atlantic Ocean.

3. What are oceans?

4. List out the names of continents according to their size.

5. Name the oceans which surround North America and South America.

Exercise H. Distinguish between

1. A Mountain and a Plateau

2. An ocean and a sea

Exercise I. Answer the following questions in detail

1. Mention the classification of land forms.

2. Write a note on plateaus.

3. Plains are highly populated. Give reasons

4. Give the important features of the Pacific Ocean.

5. Write about the importance of oceans.

Exercise J. Picture Study

1. Name the landform.

2. What order of a landform is this?

3. By which activity of river is this landform formed?

Exercise K. 1) Activity

1. Trip to the nearby area to appreciate the physical features of any kind of landform.

2. Conduct a quiz on landforms and oceans.

Exercise 2) Activity

1. Give examples for the following using an Atlas.

a. Bay:

b. Gulf:

c. Island:

d. Strait:

2. Map reading (with the help of an atlas)

a. A sea in the east of India

b. Continents in the west of Atlantic Ocean

c. Continents in the south of Arctic Ocean

d. A strait between India and Sri Lanka

e. Oceans which surround Australia

f. Find out the Isthumuses (Create more questions)

3. On the given outline map of the world, label the continents and mountain ranges.

4. On the given outline map of the world, label oceans, seas, isthumus and straits.

Internet Resources

1. www.nationalgeographic.com
2. www.nationalgeographic.org/encyclopedia/landform
3. http://mocomi.com/landforms
4. www.britannica.com.

Book-back Exercises — Questions & Answers

Answers generated strictly from the Samacheer Kalvi textbook content. Attempt each question first, then click "Show Answer" to check.

A. Choose the correct answer

1. Which of the following is the smallest ocean on Earth?

a) The Pacific Ocean b) The Indian Ocean c) The Atlantic Ocean d) The Arctic Ocean

Answer: d) The Arctic Ocean

Explanation: The Arctic Ocean is the smallest ocean covering an area of 15.56 million square kilometre.

2. The Malacca Strait connects

a) The Pacific and Atlantic Oceans b) The Pacific and Southern Oceans c) The Pacific and Indian Oceans d) The Pacific and Arctic Oceans

Answer: c) The Pacific and Indian Oceans

Explanation: Malacca strait connects the Indian Ocean and the Pacific Ocean.

3. Which of the following oceans is the busiest ocean?

a) The Pacific Ocean b) The Atlantic Ocean c) The Indian Ocean d) The Arctic Ocean

Answer: b) The Atlantic Ocean

Explanation: The Atlantic Ocean is the busiest shipping route between the Eastern and Western hemispheres.

4. The frozen continent is

a) North America b) Australia c) Antarctica d) Asia

Answer: c) Antarctica

Explanation: The Southern Ocean surrounds the continent of Antarctica and is covered by sea ice, making it the frozen continent.

5. A narrow strip of water that connects two large water bodies

a) A Strait b) An Isthmus c) An Island d) A Trench

Answer: a) A Strait

Explanation: A strait is a narrow stretch of water linking two large water bodies.

B. Fill in the blanks

1. The world's largest continent is _____

Answer: Asia

2. _____ is the mineral rich plateau in India.

Answer: Chotanagpur Plateau

3. The largest ocean is _____

Answer: Pacific Ocean

4. Deltas are _____ order landforms.

Answer: third

5. The Island continent is _____.

Answer: Australia

C. Circle the odd one out

1. Africa, Europe, Australia, Sri Lanka

Answer: Sri Lanka (Sri Lanka is an island, others are continents)

2. The Arctic Ocean, the Mediterranean Sea, the Indian Ocean, the Atlantic Ocean

Answer: The Mediterranean Sea (Mediterranean Sea is a sea, others are oceans)

3. Plateau, Valley, Plain, Mountain

Answer: Valley (Valley is a third order landform, others are second order landforms)

4. The Bay of Bengal, the Bering Sea, the China Sea, the Tasman Sea.

Answer: The Bay of Bengal (Bay of Bengal is in the Indian Ocean, others are in the Pacific Ocean)

5. The Andes, the Rockies, the Everest, the Himalayas.

Answer: The Everest (Everest is a peak, others are mountain ranges)

D. Match the following

D. Match the Following

A	B
1. The South Sandwich Trench	a) The Atlantic Ocean
2. The Milwaukee Trench	b) The Southern Ocean
3. The Mariana Trench	c) The Indian Ocean
4. The Eurasian basin	d) The Pacific Ocean
5. The Java Trench	e) The Arctic Ocean

Answers: 1-b, 2-a, 3-d, 4-e, 5-c

F. Answer in a word

1. Which is the highest plateau in the world?

Answer: Tibetan Plateau

2. Name a second order landform.

Answer: Mountains

3. Which Ocean is named after a country?

Answer: Indian Ocean

4. Name the island located in the Arabian Sea.

Answer: Lakshadweep

5. What is the deepest part of the ocean called as?

Answer: Trench

G. Answer in brief

1. What is a continent?

Answer: The vast land masses on Earth are called Continents. There are seven continents: Asia, Africa, North America, South America, Antarctica, Europe and Australia.

2. Name the continents which surround the Atlantic Ocean.

Answer: The Atlantic Ocean is bounded by North America and South America in the west and Europe and Africa in the east.

3. What are oceans?

Answer: Oceans are vast expanse of water. There are five main oceans in the world - Pacific, Atlantic, Indian, Southern and Arctic Oceans.

4. List out the names of continents according to their size.

Answer: Asia is the largest continent, whereas Australia is the smallest one. The order is: Asia, Africa, North America, South America, Antarctica, Europe and Australia.

5. Name the oceans which surround North America and South America.

Answer: The Pacific Ocean in the west and the Atlantic Ocean in the east surround North America and South America.

H. Distinguish between

1. A Mountain and a Plateau

Answer: A mountain is a landform that rises 600 metres above its surroundings with steep slopes. Plateaus are elevated portions of the Earth that have flat surfaces bounded by steep slopes.

2. An ocean and a sea

Answer: Oceans are vast expanse of water. Seas are water bodies partially or fully enclosed by land.

I. Answer the following questions in detail

1. Mention the classification of land forms.

Answer: Landforms are classified into three orders. First order landforms include continents and oceans. Second order landforms are mountains, plateaus and plains. Third order landforms are formed on mountains, plateaus and plains mainly by erosional and depositional activities of rivers, glaciers, winds and waves. Examples include valleys, beaches and sand dunes.

2. Write a note on plateaus.

Answer: Plateaus are elevated portions of the Earth that have flat surfaces bounded by steep slopes. Their elevation may be a few hundred or several thousand metres. The Tibetan Plateau is the highest plateau called the 'Roof of the world'. The flat-topped part is called Tableland. Plateaus are rich in minerals, making mining a major activity. The Deccan Plateau in India is of volcanic origin.

3. Plains are highly populated. Give reasons

Answer: Plains are flat and relatively low-lying lands usually less than 200 metres above sea level. They are formed by rivers providing water and fertile soil for agriculture. Plains have been the cradle of civilisations and are most suitable for human inhabitation. The earliest civilisations like Indus and Mesopotamian developed in river plains. They offer agricultural opportunities and easy transportation making them highly populated regions.

4. Give the important features of the Pacific Ocean.

Answer: The Pacific Ocean is the largest and deepest ocean covering one-third of Earth's area (168.72 million sq km). It is bounded by Asia and Australia in the west and North and South America in the east. It has a triangular shape with apex at Bering Strait. The deepest point is Mariana Trench (10,994 m). It contains the Pacific Ring of Fire with chain of volcanoes and was named by Ferdinand Magellan meaning calm or tranquil.

5. Write about the importance of oceans.

Answer: Oceans cover 71 percent of Earth's surface and make Earth look blue from space. They are vast expanses of water with five main oceans. Oceans serve as important shipping routes like the Atlantic Ocean being the busiest route between Eastern and Western hemispheres. They contain deep trenches, marginal seas, and islands. Oceans regulate climate and provide marine resources for human activities.

📝 Summary

1. Earth's surface consists of 71 percent water and 29 percent land, with landforms classified into first, second, and third order categories.
2. First order landforms include seven continents (Asia, Africa, North America, South America, Antarctica, Europe, and Australia) and five oceans (Pacific, Atlantic, Indian, Southern, and Arctic).
3. Asia is the largest continent while Australia is the smallest, and the Pacific Ocean is the largest ocean while the Arctic Ocean is the smallest.
4. Second order landforms are categorized as mountains, plateaus, and plains, with mountains being landforms that rise 600 metres above their surroundings with steep slopes.
5. The concept of Pangea, the super continent from 200 million years ago surrounded by Panthalasa Sea, explains how landmasses moved due to Earth's internal heat to form present-day continents and oceans.