Major Domains of the Earth (NCERT Class 6 Geography Chapter 5 Notes)

Biosphere
Biosphere is the point where three major domains of earth lithosphere, atmosphere and hydrosphere interact and life thrives.
There are four major domains of the earth: 1. Lithosphere, 2. Atmosphere, 3. Hydrosphere and 4. Biosphere.

Lithosphere
  1. The solid portion of earth on which we live and dwell is known as the Lithosphere.
  2. It comprises of rocks and a thin layer of soils that contain nutrient elements which are essential for the survival of life.
  3. There are two major divisions of the earth surface. First landmasses which are also known as continents and second ocean basins.
  4. The sea level is same everywhere. The elevation of land and its features such as mountains, plateaus and others are measured from the level of the sea, which is taken as the zero.
  5. The highest mountain peak on the Earth is Mount Everest which is measured at 8848 meters above sea level.
  6. Edmund Hillary and Tenzing Norgay Sherpa were the first men to climb the Mount Everest on 29th May 1953. Junko Tabie was the first woman to reach the Mount Everest on 16th May 1975. Bachendri Pal became first Indian woman to reach the summit on 23rd May 1975.
  7. Mariana Trench in the Pacific Ocean at 11022 meters deep is the deepest point on the Earth.

Continents
  1. There are seven major continents, namely, Asia, Europe, Africa, North America, South America, Australia and Antartica.
  2. Asia is the largest continent on Earth. It covers almost one-third of the total land area. The Tropic of Cancer passes through Asia and it is separated by the Ural Mountains. Asia is home to the Himalayas.
  3. Europe is the second smallest continent in the world and lies west of Asia. The Arctic Circle passes through Europe and bounded by water from three sides. The combined landmass of Europe and Asia is known as Eurasia.
  4. Africa is the second largest continent after Asia. The Tropic of Cancer, Tropic of Capricorn and Equator passes through Africa. Africa is the home to world largest desert, Sahara Desert and world longest river, Nile river.
  5. North America is the third largest continent in the world. It is home to world largest lake, Lake Baikal.
  6. South America is the fourth largest continent in the world. It is home to world longest mountain range, Andes and world largest river by volume, Amazon river.
  7. North America and South America are connected by a strip of land known as Isthmus of Panama.
  8. Australia is the smallest continent in the world. It entirely lies in the Southern Hemisphere. It is surrounded by water from all sides. Therefore, it is known as the Island Continent.
  9. Antartica is the southernmost continent of the world. The south pole lies on this continent. There is no human population on Antartica. However, several countries have research centres in Antartica. Maitri and Dakshin Gangotri are the Indian research centres on Antartica.

Hydrosphere
  1. More than 71 per cent of the Earth is covered with water. Therefore, Earth is also known as the blue planet.
  2. Hydrosphere consists of all water bodies including ocean, sea, lakes, glaciers, underground water and water vapour in the air.
  3. More than 97 per cent of the total water available is saline and unfit for human use. Around 2.8 per cent of fresh water is stored in the form of ice. Only 0.03 per cent of fresh water is available for human use.

Oceans
  1. Oceans form a major part of Hydrosphere. There are five oceans in the world, namely, Pacific Ocean, Atlantic Ocean, Indian Ocean, Southern Ocean and Arctic Ocean. All the oceans are interconnected with each other.
  2. There are three movements observed in ocean waters: waves, tides and currents.
  3. The Pacific Ocean is the largest ocean in the world. It covers one-third of Earth. Mariana Trench lies in the Pacific Ocean. It has a circular shape and surrounded by Asia, Australia, North America and South America.
  4. The Atlantic Ocean is the second largest ocean in the world. It is bounded by North America and South America from the west and Europe and Africa from the east. It is the busiest ocean in terms of commercial activity in the world.
  5. The Indian Ocean is named after River Indus or say India. It has a triangular shape. It is bounded by Asia in the north, Africa in the west and Australia in the east.
  6. The Southern Ocean is the ocean body which encircles Antartica and extends northward to 60° South latitude. It is entirely located within Antartica Circle. It is also known by the name of Antartica Ocean. It is the second smallest ocean in the world.
  7. The Arctic Ocean is located within the Arctic circle and surrounds the Arctic area. It is connected with the Pacific Ocean by Bering Strait. It is bounded by North America, Europe and Asia.

Atmosphere
  1. The layer of gases which surrounds Earth is known as the atmosphere.
  2. It provides us with air to breath and protects from harmful Ultraviolet rays of the Sun.
  3. It extends up to the height of 1600 km.
  4. It is divided into five layers based on factors such as temperature and composition.
  5. These five layers are troposphere, stratosphere, mesosphere, thermosphere and exosphere.
  6. It is made up of 78 per cent of Nitrogen, 21 per cent of Oxygen, and 1 per cent of other gases such as Carbon dioxide, argon and other.
  7. The density of the atmosphere is maximum at sea level and decreases as we go up. The temperature also decreases as we go up.
  8. The atmosphere exerts pressure on Earth. The pressure varies from place to place i.e. there are low and high-pressure zones on Earth. This resulting movement of air, which is also known as wind.

Biosphere
  1. The biosphere is the narrow zone of contact between land, water and air.
  2. In this zone, life exists in its all form from microbes to huge mammals exists on Earth.
  3. The three domain, lithosphere, hydrosphere and atmosphere interact and affect each other in some or other way.
  4. It is important to maintain the balance of nature between land, air and water. Any disturbance in one of these elements can affect other elements in serious way. Global Warming is one such example which is cause of over exploitation of all three elements.

Souce: NCERT Class 6 Geography