CBSE Notes For Class 6 Geography Chapter 5 Major Domains Of The Earth

CBSE Notes For Class 6 Geography Social Science Chapter 5 Major Domains Of The Earth

The surface of the Earth is a complex zone, in which the three main components of the environment meet, interact and overlap each other. These three main components of the environment are

1. Lithosphere
2. Hydrosphere
3. Atmosphere

In the Greek language, Lithos means stone, Atoms means vapour, and Hudor means water.

Lithosphere

• The solid portion of the Earth on which we live is called the lithosphere. It comprises the rocks of the Earth’s crust and the thin layers of soil that contain nutrient elements which sustain life.
• There are two main divisions of the Earth’s surface. The large landmasses are known as the continents and the massive waterbodies are called ocean basins.
• All the oceans of the world are connected with one another. The level of seawater remains the same everywhere in the world. The elevation of land is measured from the level of the sea, which is taken as zero.
• The highest mountain peak of the world is Mount Everest which is 8,848 metres above sea level.
• The deepest point of the Earth is recorded at Mariana Trench in the Pacific Ocean with a depth of 11,022 metres.

Knowledge Plus: Edmund Hillary (New Zealand) and Tenzing Norgay Sherpa (India) were the first men to climb Mt. Everest on 29th May 1953.

• Junko Tabei (Japan) was the first woman to reach the summit on 16th May 1975.
• Bachendri Pal was the first Indian woman to climb Mt. Everest on 23rd May 1984.

Continents: There are seven major continents that are separated by large water bodies. These are discussed below

Asia is the largest continent and covers about one-third of the total land area of the world. Asia lies in the Eastern Hemisphere. The Tropic of Cancer passes through this continent.

Asia is separated from Europe by the Ural mountains on the West. The combined landmass of Europe and Asia is called Eurasia.

Europe It lies to the West of Asia and is much smaller in size than Asia. The Arctic Circle passes through it. It is bound by water bodies on three sides.

Africa is the second largest continent after Asia.

• A large part of Africa lies in the Northern Hemisphere.
• It is the only continent through which the Tropic of Cancer, the Equator and the Tropic of Capricorn pass.
• The 0° latitude or Equator passes almost through the middle of this continent.
• The largest hot desert in the world, the Sahara Desert, is located in Africa. The Nile River, which is the longest river in the world, flows through Africa. It is surrounded by oceans and seas on all sides.

North America is the third largest continent in the world. It lies completely in the Northern and Western hemispheres.

• It is surrounded by three oceans. It is linked with South America by a narrow strip of land called the Isthmus of Panama.

South America It lies mostly in the Southern Hemisphere. The world’s longest mountain range, Andes runs through its length from North to South.

• The world’s largest river Amazon is located in this continent.

Australia It lies completely in the Southern hemisphere and is the smallest continent. It is also called an island continent. It is surrounded by the oceans and seas on all sides.

Antarctica is a huge continent and completely lies in the Southern hemisphere. The South Pole lies almost at the centre of this continent.

• The continent remains permanently ice-covered due to its position in the South Polar region. There are no permanent human settlements.
• Many countries have established their research stations in Antarctica. India also has established research stations in Antarctica, named Maitri and Dakshin Gangotri.

CBSE Notes For Class 6 Geography Chapter 5  Hydrosphere

• The area covered by water on the Earth’s surface is called the hydrosphere. More than 71 per cent of the Earth is covered with water and 29 per cent with land. The Earth is called the blue planet due to the excess water cover.
• Hydrosphere consists of water in all its forms including running water in oceans and rivers, ice in glaciers, underground water and water vapour in the atmosphere.
• More than 97 per cent of the Earth’s water is salty and is present in the oceans. A large proportion of the rest of the water is present in the form of ice sheets and glaciers or underground water. A very small percentage of water is available as fresh water for human consumption.

CBSE Notes For Class 6 Geography Chapter 5  Oceans

Oceans are a major part of the hydrosphere. They are all interconnected. The ocean waters are always moving. The three main movements of ocean waters are the waves, the tides and the ocean currents.

There are five major oceans that are discussed below

Pacific Ocean It is the largest ocean that is spread over one-third of the Earth. Mariana Trench, the deepest part of the Earth, lies in the Pacific Ocean.

• The shape of the Pacific Ocean is almost circular. It is surrounded by Asia, Australia, North and South America.

Atlantic Ocean It is the second largest ocean. It is S-shaped with a highly irregular coastline, which provides an ideal location for natural harbours and ports.

• From a trade and commerce point of view, it is the busiest ocean.
• It is surrounded by the North and South Americas on the Western side, and Europe and Africa on the Eastern side.

Indian Ocean It is the only ocean that is named after a country i.e. India. The shape of the ocean is triangular. It is bound by Asia in the North, by Africa in the West and by Australia in the East.

Southern Ocean It surrounds the Antarctica continent and extends Northward to 60 degrees South latitude.

Arctic Ocean It is located within the Arctic Circle and surrounds the North Pole. It is connected with. the Pacific Ocean by a narrow stretch of shallow water, which is called the Bering Strait. It is surrounded by Northern coasts of North America and Eurasia.

CBSE Notes For Class 6 Geography Chapter 5  Atmosphere

• The gaseous layers that surround the Earth are called the Atmosphere where oxygen, nitrogen, carbon dioxide and other gases are found.
• This thin cover of air is considered an essential aspect of the planet as it provides the air we breathe and also protects us from the harmful effects of the Sun’s rays.
• The atmosphere extends up to a height of about 1,600 km. It is divided into five layers on the basis of its composition, temperature and other properties.
• These layers starting from Earth’s surface are called the troposphere, the stratosphere, the mesosphere, the thermosphere and the exosphere.
• The atmosphere is composed mainly of nitrogen (78 per cent) and oxygen (21 per cent) which make up 99 per cent of clean, dry air. It also includes carbon dioxide, argon and other gases which make up the rest 1 per cent of the air.
• Oxygen is important for breathing and nitrogen is for the growth of living beings. Carbon dioxide is important for the absorption of heat radiated by the Earth to keep it warm and for the respiration of plants.
• The density of the atmosphere is maximum at the sea level and decreases as going up. The temperature also decreases as going upwards.
• The pressure exerted by the atmosphere on the Earth also varies from place to place. Some experience high pressure and some experience low pressure. Air moves from high pressure to low pressure and the movement of it is called wind.

Knowledge Plus climbers experience problems in breathing due to a decrease in the density of air. Thus, they have to carry with them oxygen cylinders to be able to breathe at high altitudes.

CBSE Notes For Class 6 Geography Chapter 5  Biosphere – The Domain of Life

• The word Bios means life. The narrow zone where land, water and air are found together and which contains all forms of life, is called Biosphere.
• There are several organisms that vary in size, from microbes and bacteria to large mammals. All living organisms are linked to each other and to the biosphere for survival.
• The living organisms in the biosphere can be broadly divided into the plant kingdom and the animal kingdom.
• The three domains of the Earth that are lithosphere, atmosphere and hydrosphere, are interlinked with each other and affect each other. For example, cutting forests to fulfil our needs of wood, or clearing land for cultivation may lead to the fast removal of soil from slopes.
• Similarly, Earth’s surface may be changed due to natural calamities like earthquakes, landslides, etc.
• For example, there could be submergence of land, like the parts of Andaman & Nicobar Islands were submerged under water during the Tsunami.
• Apart from this, the discharge of wastewater and material into water bodies makes the water unsuitable for human use and damages other forms of life.
• Air is polluted by emissions from industries, thermal power plants and vehicles. Carbon dioxide (CO₂) is an important constituent of air, but if the amount of CO₂ increases, it leads to an increase in global temperatures. This is termed as global warming.
• Thus, it is essential to limit the use of resources of the Earth to maintain the balance of nature between the domains of the Earth.