Major Domains of the Earth Class 6 Geography Notes | StudyTution

Lithosphere

• The surface of the earth is a complex zone in which three main components of the environment meet, overlap and interact.
• The solid portion of the earth on which we live is called the Lithosphere.

Atmosphere

• The gaseous layers that surround the earth, is the Atmosphere, where oxygen, nitrogen, carbondioxide and other gases are found.

Hydrosphere

• Water covers a very big area of the earth’s surface and this area is called the Hydrosphere.
• The Hydrosphere comprises water in all its forms, that is, ice, water and water vapour.

Biosphere 

• The Biosphere is the narrow zone where we find land, water and air together, which contains all forms
  of life.

LITHOSPHERE

• The solid portion of the earth 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 organisms.
• The large landmasses are known as the continents and the huge water bodies are called the ocean basins.
• All the oceans of the world are connected with one another.
• The level of seawater remains the same everywhere.
• Elevation of land is measured from the level of the sea, which is taken as zero.
• The highest mountain peak Mt. Everest is 8,848 metres above the sea level.
• The greatest depth of 11,022 metres is recorded at Mariana Trench in the Pacific Ocean.

Continents

• There are seven major continents.
• These are separated by large water bodies.
• These continents are – Asia, Europe, Africa, North America, South America, Australia and Antarctica.

1. Asia

• Asia is the largest continent.
• It covers about onethird of the total land area of the earth.
• The continent 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 the Eurasia (Europe + Asia).

2. Europe

• Europe is much smaller than Asia.
• The continent lies to the west of Asia.
• The Arctic Circle passes through it. It is bound by water bodies on three sides

3. Africa

• Africa is the second largest continent after Asia.
• The Equator or 00 latitude runs almost through the middle of the continent.
• A large part of Africa lies in the Northern Hemisphere.
• The Sahara Desert, the world’s largest hot desert, is located in Africa.
• The continent is bound on all sides by oceans and seas.
• World’s longest river the Nile, flows through Africa.

4. North America

• North America is the third largest continent of the world.
• It is linked to South America by a very narrow strip of land called the Isthmus of Panama.
• The continent lies completely in the Northern and Western Hemisphere.
• Three oceans surround this continent

5. South America 

• South America lies mostly in the Southern Hemisphere.
• The Andes, world’s longest mountain range, runs through its length from north to south
• South America has the world’s largest river, the Amazon.

6. Australia

• Australia is the smallest continent that lies entirely in the Southern Hemisphere.
• It is surrounded on all sides by the oceans and seas.
• It is called an island continent.

7. Antarctica

• Antarctica, completely in the Southern Hemisphere, is a huge continent.
• The South Pole lies almost at the centre of this continent.
• It is located in the South Polar Region, it is permanently covered with thick ice sheets.
• There are no permanent human settlements.
• Many countries have research stations in Antarctica.
• India also has research stations there.
• These are named as Maitri and Dakshin Gangotri

HYDROSPHERE

• The earth is called the blue planet.
• More than 71 per  cent of the earth is covered with water and 29 per cent is with land.
• Hydrosphere consists of water in all its forms.
• Running water in oceans and rivers and in lakes, ice in glaciers, underground water and the water vapour in atmosphere, all comprise the hydrosphere.
• More than 97% of the Earth’s water is found in the oceans and is too salty for human use.
• A large proportion of the rest of the water is in the form of icesheets and glaciers or under the ground and a very small percentage is available as fresh water for human North and South Americas surround it.
• The Atlantic Ocean is the second largest Ocean in the world.
• It is ‘S’ shaped.
• It is flanked by the North and South Americas on the western side, and Europe and Africa on the eastern side.

1. Ocean

• The coastline of Atlantic Ocean is highly indented.
• This irregular and indented coastline provides ideal location for natural harbours and ports
• The Indian Ocean is the only ocean named after a country, that is, India.
• The shape of ocean is almost triangular.
• In the north, it is bound by Asia, in the west by Africa and in the east by Australia.
• The Southern Ocean encircles the continent of Antarctica and extends northward to 60 degrees south
  latitude.
• The Arctic Ocean 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 known as Berring strait.
• It is bound by northern coasts of North America and Eurasia.

ATMOSPHERE

• The earth is surrounded by a layer of gas called the atmosphere.
• This thin blanket of air is an integral and important aspect of the planet.
• It provides us with the air we breathe and protects us from the harmful effects of sun’s rays.
• The atmosphere extends up to a height of about 1,600 kilometres.
• 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 and oxygen, which make up about 99 per cent of clean,
  dry air.

Air

• Nitrogen 78 per cent, oxygen 21 per cent and other gases like carbondioxide, argon and others comprise 1 per cent by volume.
• Oxygen is the breath  of life while nitrogen helps in the growth of living organisms.
• Carbon dioxide, though present in minute amount, is important as it absorbs heat radiated by the earth, thereby keeping the planet warm.
• It is alsoessential for the growth of plants.
• The density of the atmosphere varies with height. It is maximum at the sea level and decreases rapidly as we go up.
• The climbers experience problems in breathing due to this decrease in the density of air.
• They have to carry with them oxygen cylinders to be able to breathe at high altitudes.
• The temperature also decreases as we go upwards.
• The atmosphere exerts pressure on the earth.
• Air moves from high pressure to low pressure. Moving air is known as wind.

BIOSPHERE – THE DOMAIN OF LIFE

• The biosphere is the narrow zone of contact between the land, water and air.
• All the living organisms including humans are linked to each other and to the biosphere for survival.
• The organisms in the biosphere may broadly be divided into the plant kingdom and the animal kingdom.
• The three domains of the earth interact with each other and affect each other in some way or the other.
• Cutting of forests for fulfilling our needs of wood, or clearing land for agriculture may lead to fast removal of soil from slopes.
• Similarly earth’s surface may be changed due to natural calamities like earthquakes.
• There could be submergence of land, as happened in the case of Tsunami recently.
• Parts of Andaman & Nicobar islands were submerged under water. Discharge of waste material into lakes and rivers makes the water unsuitable for human use.
• It also damages other forms of life.
•  Emission from industries, thermal power plants and vehicles, pollute the air.
• Carbon dioxide (CO2 ) is an important constituent of air.
• But increase in the amount of CO2 leads to increase in global temperatures.
• This is termed as global warming.
• There is  a need to limit the use of resources of the earth to maintain the balance of nature between the domains of the lithosphere, the atmosphere and the hydrosphere.