Major Domains of the Earth: Geography UPSC

Major domains of the earth are a basic concept in Geography. The earth’s surface is a complex zone in which the three major components of the environment meet, overlap and interact.

The Four Domains of the Earth

  • Lithosphere: The solid portion of the earth
  • Atmosphere: The gaseous layers that surround the earth
  • Hydrosphere: Water covers a very big area of the earth’s surface and this area is called the Hydrosphere
  • Biosphere: It is the narrow zone where land, water and air together are found.

Lithosphere

The solid portion of the earth on which we live—

  • Comprises the rocks of the earth’s crust and the thin layers of soil that contains nutrient elements which sustain organisms
  • Continents- large landmasses
  • Ocean basins- the huge water bodies

Continents

There are seven major continents and these are separated by large water bodies.

  1. Asia
  • Asia is the largest continent covering one-third of the total land area of the earth.
  • The continent lies in the Eastern Hemisphere.
  • The Tropic of Cancer passes through Asia.
  • The Ural Mountains on the west separates from Europe.
  1. Europe
  • Europe is much smaller than Asia lying to the west of Asia.
  • The Arctic Circle passes through it.
  • Its three sides are bound by water bodies.
  1. Africa
  • Africa is the second-largest continent after Asia.
  • A large part of Africa lies in the Northern Hemisphere.
  • Africa is the only continent through which the Tropic of Cancer, the Equator and the Tropic of Capricorn pass.
  1. North America
  • North America is the third largest continent in the world.
  • The continent lies completely in the Northern and Western Hemisphere.
  • The Isthmus of Panama a narrow strip links North America and South America.
  • This continent is surrounded by three oceans and they are the Atlantic Ocean, the Pacific Ocean, and the Arctic Ocean.
  1. South America
  • South America lies mostly in the Southern Hemisphere.
  • It is surrounded by two oceans; the Pacific Ocean on the west and the Atlantic Ocean on the east and north.
  1. 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.
  1. Antarctica
  • Antarctica is a huge continent and lies completely in the Southern Hemisphere.
  • The South Pole lies in the South Polar Region almost at the centre of this continent and is permanently covered with thick ice sheets.

Atmosphere

The gaseous layers that surround the earth— where oxygen, nitrogen, carbon dioxide and other gases are found and interact

  • Provides the air we breathe + Protects us from the harmful effects of sun’s rays
  • The changes in the atmosphere produce changes in the weather and climate
  • Extends up to a height of about 1,600 kilometres
  • The gravitational force of the earth holds the atmosphere around it
  • Divided into five layers based on composition, temperature and other properties— troposphere, the stratosphere, the mesosphere, the thermosphere and the exosphere.
  • Composed mainly of—
    • Nitrogen and oxygen, which make up about 99 per cent of clean, dry air.
    • Nitrogen (helps in the growth of living organisms) 78 per cent, oxygen 21 per cent and other gases like carbon dioxide, argon and others comprise 1 per cent by volume
    • Carbon dioxide: Present in minute amount but is important as it absorbs heat radiated by the earth, thereby keeping the planet warm and also essential for the growth of plants.
  • The density of the atmosphere: Maximum at the sea level and decreases rapidly as we go up
  • Wind: Moves from high pressure to low pressure

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 the land. Hydrosphere consists of water in all its forms.
  • More than 97% of the Earth’s water is found in the oceans and is too salty for human use.
  • Hydrosphere consists of water in all its forms like running water in oceans and rivers and in lakes, ice in glaciers, underground water and the water vapour in the atmosphere.
  • 97% of the Earth’s water is found in the oceans and is too salty, the rest of the water is in the form of ice sheets and glaciers or under the ground and a very  a small percentage is available as freshwater for human use

Oceans

  • The three chief movements of ocean waters are the waves, the tides and the ocean currents.
  • Oceans are the major part of the hydrosphere and they are all interconnected.
  • The five major oceans in order of their size are
    • the Pacific Ocean: It is almost circular in shape. Asia, Australia, North and South Americas surround it.
    • the Atlantic Ocean: It 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.
    • the Indian Ocean: It is the only ocean named after a country, that is, India. The shape of the 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: It surrounds the continent of Antarctica
    • the Arctic Ocean: It is located within the Arctic Circle and surrounds the North Pole. The Barring strait a narrow stretch of shallow water connects it with the Pacific Ocean.

Biosphere – The Domain of Life 

  • The biosphere is the narrow zone of contact between the land, water and air.
  • It is the zone where life exists that makes this planet unique.
  • The organisms in the biosphere are commonly divided into:
    • the plant kingdom
    • the animal kingdom
  • The three domains of the earth interact with each other and affect each other in some way or the other.

Major Domains of the Earth


Strait: A narrow passage of water connecting two seas or two other large areas of water.

Example:

1. Malacca Strait

Joins: Andaman Sea & South China Sea

Location: Indonesia –Malaysia

2. Palk Strait      

Join: Palk Bay & Bay of Bengal

Location: India-Sri Lanka

3. Sunda Strait   

Join: Java Sea & Indian Ocean

Location: Indonesia

 

4. Yucatan Strait

Join: Gulf of Mexico and Caribbean Sea

Location: Mexico-Cuba

5. Mesina Strait  

Join: Mediterranean Sea

Location: Italy-Sicily

6. Otranto Strait

Join: Adriatic Sea & Ionian Sea

Location: Italy-Albania

7. Bab-el-Mandeb Strait        

Join: Red Sea & Gulf of Aden

Location: Yemen-Djibouti

8. Cook Strait     

Join: South Pacific Ocean

Location:  New Zealand (North & South Islands)

9. Mozambique Strait  

Join: Indian Ocean

Location: Mozambique -Malagasy

10. North Channel

Join: Irish Sea & Atlantic Ocean

Location: Ireland-England

11. Taurus Strait

Join: Arafura Sea & Gulf of Papua

Location: Papua New Guinea — Australia

12. Bass Strait

Join: Tasman Sea & South Sea

Location: Australia

13. Bering Strait

Join: Bering Sea & Chuksi Sea

Location: Alaska-Russia

14. Bonne-Fasio Strait

Join: Mediterranean Sea

Location: Corsika — Sardinia

15. Bosporous Strait   

Join: Black Sea and Marmara Sea

Location: Turkey

16. Dardenleez Strait  

Join: Marmara Sea and Agean Sea

Location: Turkey

17. Davis Strait  

Join: Baffin Bay & Atlantic Ocean

Location: Greenland-Canada

18. Denmark Strait     

Join: North Atlantic and Arctic Ocean

Location: Greenland-Iceland

19. Dover strait  

Join: English Channel & North Sea

Location: England-France

20. Florida Strait

Join: Gulf of Mexico and Atlantic Ocean

Location: USA-Cuba

21. Hormuz Strait       

Join: Gulf of Persia & Gulf of Oman

Location: Oman-Iran

22. Hudson strait         

Join: Gulf of Hudson & Atlantic Ocean

Location: Canada

23. Gibraltar Strait      

Join: Mediterranean Sea & Atlantic Ocean

Location: Spain-Morocco

24. Magellan strait       

Join: Pacific and South Atlantic Ocean

Location: Chile

25. Makkassar Strait   

Join: Java Sea & Celebeze Sea

Location: Indonesia

26. Tsungaru Strait     

Join: Japan Sea and Pacific Ocean

Location: Japan (Hokkaido-Honshu Island)

27. Tatar Strait  

Join: Japan Sea & Okhotsk Sea

Location: Russia (East Russia-Sakhalin Islands)

28. Fovex Strait 

Join: South Pacific Ocean

Location: New Zealand (South Island- Stewart Island)

29. Formosa Strait      

Join: South China Sea & East China Sea

Location: China-Taiwan


Isthmus: A narrow strip of land with sea on either side, forming a link between two larger areas of land. The Isthmus of Panama is a narrow strip of land at the southernmost end of Central America. It lies between the Pacific Ocean and the Caribbean Sea while linking North and South America.


 

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