NCERT Class 6 - Social Science - Geography
Chapter 5 - MAJOR DOMAINS OF THE EARTH
Table of Contents
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INTRODUCTION
- The surface of the earth has three main components :
- Lithosphere - The solid portion of the earth on which we live.
- Atmosphere - The gaseous layers that surround the earth (oxygen, nitrogen, carbon dioxide, and other gases).
- Hydrosphere - Water that covers the earth’s surface.
- Biosphere - The zone where the land, water, and air together, which helps Sustaining Life on Earth
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.
- There are two main divisions of the earth’s surface.
- Continents
- Oceans
- The highest mountain peak Mt. Everest is 8,848 meters.
- The greatest depth of 11,022 meters is recorded at Mariana Trench in the Pacific Ocean.
- Edmund Hillary (New Zealand) and Tenzing Norgay Sherpa (India) were the first men to climb the highest mountain peak Mt. Everest on 29th May 1953.
- Junko Tabei (Japan) was the first woman to reach the summit of Mount Everest on 16th May 1975.
- In 1992, 17 years after once again Junko Tabei (Japan) was recorded as the first woman to climb the highest mountains on each of the 7 continents (Seven Summits).
- The first Indian woman to climb the highest peak on 23rd May, 1984 was Bachendri Pal.
CONTINENTS
- There are seven major continents.
- These continents are – Asia, Europe, Africa, North America, South America, Australia, and Antarctica.
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.
Europe:
- This continent lies to the west of Asia.
- The Arctic Circle passes through it.
- It is bound by water bodies on three sides.
Africa:
- Africa is the second largest continent after Asia.
- The Equator or 0-degree latitude runs almost through the middle of the continent.
- A large part of Africa lies in the Northern Hemisphere.
- It is the only continent through which the Tropic of Cancer, the Equator, and the Tropic of Capricorn pass.
- The Sahara Desert, the world’s largest hot desert, is located in Africa.
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 Hemispheres.
- Three oceans surround this continent.
- Oceans that surround the continent of North America are the Pacific Ocean, Atlantic Ocean, and Arctic Ocean.
- Ursa
South America:
- South America lies mostly in the Southern Hemisphere.
- Two oceans surround it on the east and the west.
- The Andes, the world’s longest mountain range, runs through its length from north to south.
- South America has the world’s largest river, the Amazon.
Australia:
- Australia is the smallest continent that lies entirely in the Southern Hemisphere.
- It is surrounded on all sides by the oceans.
- It is called an island continent.
Antarctica:
- Antarctica is completely in the Southern Hemisphere.
- The South Pole lies almost at the centre of this continent.
- It is permanently covered with thick ice sheets. There are no permanent human settlements.
- India also has research stations there. These are named as Maitri and Bharati.
HYDROSPHERE
- The Earth is more than 71 percent of the earth is covered with water and 29 percent is with land.
- Hydrosphere consists of oceans and rivers and lakes, ice in glaciers, underground water, and atmospheric water vapor.
- More than 97% of the Earth’s water is present in the oceans.
OCEANS:
- The five major oceans are the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, the Southern Ocean, and the Arctic Ocean.
The pasific ocean:
- The Pacific Ocean is the largest ocean. It is spread over one-third of the earth.
- Mariana Trench, the deepest part of the earth, lies in the Pacific Ocean.
- The Pacific Ocean is almost circular in shape.
- Asia, Australia, and North and South America surrounded it.
The pasific ocean:
- The Atlantic Ocean is the second-largest Ocean in the world.
- It is ‘S’ shaped.
- The coastline of the Atlantic Ocean is highly indented.
- From the point of view of commerce, it is the busiest Ocean.
The Indian Ocean:
- 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:
- The Southern Ocean encircles the continent of Antarctica and extends northwards to 60 degrees south latitude.
The Arctic Ocean:
- 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 the Berring strait.
- It is bound by the northern coasts of North America and Eurasia.
ATMOSPHERE
- The earth is surrounded by a layer of gas called the atmosphere.
- The atmosphere extends up to a height of about 1,600 kilometers.
- The atmosphere is divided into five layers. These layers starting from the earth are:
- Troposphere
- Stratosphere
- Mesosphere
- Thermosphere
- Exosphere
- The atmosphere is composed mainly of nitrogen and oxygen, which make up about 99 percent of clean, dry air.
- Nitrogen is 78 percent, oxygen 21 percent, and other gases like carbon dioxide, argon, and others comprise 1 percent by volume.
- Carbon dioxide is important as it absorbs heat radiated by the earth, thereby keeping the planet warm.
- The density of the atmosphere is maximum at the sea level and decreases rapidly as we go up.
- The temperature also decreases as we go upwards.
- The atmosphere exerts pressure on the Earth. Air moves from high pressure to low pressure.
BIOSPHERE – THE DOMAIN OF LIFE
- The biosphere is the narrow zone of contact between the land, water, and air.
- All 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.
- An increase in the amount of CO2 leads to an increase in global temperatures. This is termed global warming.
