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• The earth is the only planet whichhas life. Human beings can live herebecause the life sustaining elementsof land, water and air are presenton the earth.
• The surface of the earth is acomplex zone in which three maincomponents of the environmentmeet, overlap and interact.
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• The solid portion of the earth on which we liveis called the LITHOSPHERE.
• The gaseous layers that surround the earth, isthe ATMOSPHERE, where oxygen, nitrogen,carbon dioxide and other gases are found.
• Water covers a very big area of the earth’ssurface and this area is called theHYDROSPHERE. The Hydrosphere compriseswater in all its forms, that is, ice, water andwater vapour.
• The BIOSPHERE is the narrow zone where wefind land, water and air together, whichcontains all forms of life.
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LITHOSPHERE• The solid portion of the earth is called theLithosphere.
• It comprises the rocks of the earth’s crust and thethin layers of soil that contain nutrient elementswhich sustain organisms.
• There are two main divisions of the earth’s surface.
• The large landmasses are known as the continentsand the huge water bodies are called the oceanbasins.
• All the oceans of the world are connected with oneanother.
• The level of seawater remains the same everywhere.
• Elevation of land is measured from the level of thesea, which is taken as zero.
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Continents• There are seven major
continents.
• These are separated bylarge water bodies.
• These continents are –Asia, Europe, Africa,North America, SouthAmerica, Australia andAntarctica.
• The greater part of theland mass lies in theNorthern Hemisphere.
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Asia
• Asia is the largest continent.
• It covers about one third 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).
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Europe
• Europe is much smaller than Asia.
• The continent lies to the west ofAsia. The Arctic Circle passesthrough it.
• It is bound by water bodies onthree sides.
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Africa• Africa is the second largest continent after Asia.
• The Equator or 0 latitude runs almost through themiddle of the continent.
• A large part of Africa lies in the Northern Hemisphere.
• It is the only continent through which the Tropic ofCancer, the Equator and the Tropic of Capricorn pass.
• The Sahara Desert, the world’s largest hot desert, islocated in Africa.
• The continent is bound on all sides by oceans and seas.
• The world’s longest river the Nile, flows throughAfrica.
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North America
• North America is the third largest continent ofthe world.
• It is linked to South America by a very narrowstrip of land called the Isthmus of Panama.
• The continent lies completely in the Northernand Western Hemisphere.
• Three oceans surround this continent are theAtlantic Ocean , the Pacific Ocean and theArctic Ocean.
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South America
• South America lies mostly in the SouthernHemisphere.
• The Atlantic Ocean and the Pacific Oceansoceans surround it on the east and thewest.
• 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.
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Australia
• Australia is the smallestcontinent that lies entirely inthe Southern Hemisphere.
• It is surrounded on all sidesby the oceans and seas.
• It is called an island continent.
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Antarctica• Antarctica, completely in the Southern
Hemisphere, is a huge continent.
• The South Pole lies almost at the centre of thiscontinent.
• As it is located in the South Polar Region, it ispermanently covered with thick ice sheets.
• There are no permanent human settlements.
• Many countries have research stations inAntarctica.
• India also has research stations there. These arenamed as Maitri and Dakshin Gangotri.
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Comparative size of the continents
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