[GS] [Geography] Continents, Oceania, Pacific Ocean, Atlantic Ocean, Indian Ocean, Arctic Ocean, Hot Currents, Cold Currents, Biosphere, Lithosphere & Hydrosphere

[GS]

[Geography]

Continents, Oceania, Pacific Ocean, Atlantic Ocean, Indian Ocean, Arctic Ocean, Hot Currents, Cold Currents, Biosphere, Lithosphere & Hydrosphere

Continents of the World

• Asia, Africa, North America, South America, Europe, Australia and Antarctica are the seven continents.

Oceania

• Australia with New Zealand, Tasmania, New Guinea and the Pacific Islands (Micronesian, Melanesia and Polynesian Islands) is called Australasia by some geographers while some others call it “Oceania”, which includes proximate islands (Caribbean countries etc).

Oceans on the Earth

• There are four oceans. In order of their size, they are: Pacific Ocean, Atlantic Ocean, Indian Ocean and Arctic Ocean.

Pacific Ocean

• The Explorer Ferdinand Magellan, who circumnavigated the Earth, named the ocean “Pacific” meaning calm or peaceful.

• The Pacific Ocean (Area: 166,240,000 sq.km.) is the largest ocean of the world.

• It is the deepest ocean with an average depth of 4,200 m.

• The Mariana Trench is the world’s deepest trench with a depth of 11,033 metres (36,201 feet).

• Most of the islands of this ocean are of volcanic or coral origin.

Atlantic Ocean

• The Atlantic Ocean (Area is the second largest ocean in the world.

• Its name is derived from Atlas, a Titan ( Giant ) in Greek mythology.

• The Atlantic Ocean has the longest coastline.

• The Atlantic Ocean the busiest ocean for trade and commerce since its shipping routes connect the two most industrialized regions, namely Western Europe and N.E. United States of America.

• The Atlantic Ocean was formed millions of years ago when a right opened up in the Gondwanaland and the continents of South American and Africa separated. The separation continues even today and the Atlantic Ocean is still widening.

• The continental islands of Newfoundland and British Isles are the major ones.

• Volcanic Island are fewer and they include those of Cuba, Jamaica and Puerto Rico, Iceland is the largest island of volcanic origin.

Indian Ocean

• The Indian Ocean is the only ocean named after a country.

• The Indian Ocean is deeper than the Atlantic Ocean.

• It contains numerous continental islands; Madagascar and Sri Lanka are being the largest ones.

• Some of the island of volcanic origin is those of Mauritius, Andaman origin.

South Indian Ocean

• Warm currents : (1) South Equatorial (2) Mozambique (3)  Madagascar (4) Agulhas

• Cool Currents: (1) Antarctic drift (2) West Australian currents.

Arctic Ocean

• The Arctic Ocean (Area: 13, 230, 000 sq. km.) is the smallest of the oceans.

• It lies within the Arctic Circle, hence the name Arctic Ocean.

• The North Pole lies in the middle of the Arctic Ocean.

• Most of the parts of Arctic Ocean remain frozen with thick ice for most of the days every year.

• It is the shallowest of all oceans, with an average depth of 1,500 m.

• It has the least salinity of all the oceans. It has a salinity of 20 units per thousand.

Ocean Current

• The flow of a large amount of water in a definite direction with a great intensity is known as Ocean Current.

• Ocean Currents are of two types- Hot and Cold.

Hot Currents

• The currents flowing from tropical zones of lower latitudes to higher temperate and sub polar zones are known as hot water currents.

Cold Currents

• The currents flowing from higher latitudes to lower latitudes are known as cold water currents.

• The only exception to the conduction of ocean currents is found in the Indian Ocean. The flow of currents changes here with a change in the direction of the Monsoon Winds. The hot currents flow towards the warmer oceans.

Biosphere

• The part of the Earth where life exists is called the Biosphere (‘bios’ means ‘life’).

• The Earth is the only planet of the solar system that supports life.

Lithosphere

• The uppermost layer of the Earth’s crust which is capable of supporting life is called Lithosphere.

• The Lithosphere ( or land ) covers two-sevenths or 29.22%

(14, 990, 41,182 sq km ) of the total surface area of the earth.

Hydrosphere

• Hydrosphere (or sea) covers five-sevenths or more accurately 70.7% (36, 10, 59,229 sq.km.) of the total surface area of the earth.

• Water is freely available in the gaseous, liquid and solid state.

• It is necessary for carrying out chemical reactions within the bodies of the living organisms.

• Water also dissolves and transports nutrients from the soil to the plants.

• It is used by plants for making food.