GEO (VI)-LESSON-5
MAJOR DOMAINS OF
THE EARTH
(LESSON NOTES)
v INTRODUCTION
Ø The earth is the only planet where human beings find three life sustaining elements—land, water and air.
Ø The surface of the earth is a complex zone. Here three main components of the environment—lithosphere, atmosphere and hydrosphere meet, overlap and interact.
§ The lithosphere refers to the solid portion of the earth where we live.
§ The atmosphere refers to the gaseous layers which surrounding the earth.
§ The hydrosphere refers to the water bodies that exist on the earth’s surface.
§ The biosphere is the narrow zone where we find land, water and air interact with each other for life exists.
v LITHOSPHERE
Ø The solid portion of the Earth where we live is called as lithosphere. It comprises the rocks of the earth’s crust and the thin layers of soil. There are mainly two main divisions of the earth’s surface: -
§ Continents- The large landmasses are known as the continents
§ Ocean basins- The huge water bodies are called the ocean basins
Ø Continents
§ The large landmasses are known as the continents. There are seven major continents. The greater part of the land mass lies in the Northern Hemisphere.
§ ASIA
· Asia is the largest continent. It covers about one third of the total land area of the earth. It lies in the Eastern Hemisphere. 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).
§ AFRICA
· Africa is the second largest continent. It is bound on all sides by oceans and seas. It is the only continent through which the Tropic of Cancer, the Equator and the Tropic of Capricorn pass. World’s largest hot desert- Sahara and world longest river -Nile River in this continent.
§ NORTH AMERICA
· It 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.
§ 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. It also has the world’s largest river, the Amazon.
§ EUROPE
· Europe is second smallest continents. The continent lies to the west of Asia. The Arctic Circle passes through it. It is bound by water bodies on three sides.
§ ANTARCTICA
· Antarctica is permanently covered with thick ice sheets. Many countries have research stations in Antarctica. India also has research stations there. These are named as Maitri and Dakshin Gangotri.
§ AUSTRALIA
· It is the smallest continent. It is also called an island continent and a country also.
v HYDROSPHERE
Ø The hydrosphere refers to the water bodies that exist on the earth’s surface. More than 71 % per cent of the Earth is covered with water, therefore, the Earth is called the blue planet.
Ø OCEANS
§ More than 97% of the Earth’s water is found in the oceans. There are five major oceans in the world. They are interconnected. There are three movement of ocean water are
· Waves
· Tides
· Ocean currents
§ THE PACIFIC OCEAN: -
· It is the largest ocean. It is spread over one-third of the earth.
· Mariana Trench ( 11022 M) the deepest part of the earth, lies in the Pacific Ocean.
· The Pacific Ocean 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 irregular and indented coastline provides ideal location for natural harbours and ports. It is busiest ocean.
§ THE INDIAN OCEAN: -
· 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.
· It is the only ocean named after a country, that is, India
§ SOUTHERN OCEAN: -
· The Southern Ocean encircles the continent of Antarctica and extends northward to 60 degrees south latitude.
§ THE ARCTIC OCEAN: -
· It is the smallest 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 known as Berring strait.
· It is bound by northern coasts of North America and Eurasia.
v ATMOSPHERE
Ø This thin blanket of air that surround the Earth is called as Atmosphere.
Ø It provides us oxygen and other gases and also protects us from the harmful effects of the sun’s rays.
Ø The atmosphere extends up to a height of about 1,600 kilometres. Its density highest at sea level and decrease as we go up. So, climbers have to carry with them oxygen cylinders.
Ø Atmosphere also exerts pressure on the earth, known as Air pressure. It decreases as the temperature increase. Air move from High pressure to low pressure.
Ø The atmosphere is divided into five layers—the troposphere, the stratosphere, the mesosphere, the thermosphere and the exosphere.
v BIOSPHERE – THE DOMAIN OF LIFE
Ø The biosphere is the narrow zone of contact between the land, water and air, where life exists.
Ø The organisms in the biosphere may broadly be divided into the plant kingdom and the animal kingdom.
Ø All the living organisms including humans are linked to each other and to the biosphere for survival.
v GLOBAL WARMING.
Ø Increase in the amount of C02 leads to an increase in global temperature. This is termed as global warming.
v STRAIT: It is a narrow passage of water connecting two large water bodies like seas and oceans. The strait between India and Sri Lanka is known as Palk strait.
v ISTHMUS: It is a narrow strip of land joining two landmasses. North America and south America join by Panama Isthmus.
v Edmund Hillary (New Zealand) and Tenzing
Norgay Sherpa (India) were the first men to climb the highest mountain peak Mt.
Everest on the planet earth on 29th May, 1953.
v Junko Tabei (Japan) was the first woman
to reach the summit on 16th May, 1975.
v The first Indian woman to climb the highest
peak on 23rd May, 1984 was Bachendri Pal.
v Santosh Yadav climbed twi times on Mt
Everest.
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