NCERT / CBSE NOTES : Chapter Summary


Major Domains of the Earth

The Complex Surface of the Earth

The surface of the earth is composed of:
  • The solid portion where we live is the Lithosphere. The Lithosphere is defined as the realm of the earth (outer part) consisting of a solid crust (rocks). Thin layers of soil that contain nutrient elements.
  • The air that we breathe is part of the gaseous layers that surround the earth. The blanket of these gaseous layers forms the Atmosphere. The atmosphere contains gases like oxygen, nitrogen and carbon dioxide.
  • Water covers about 70% of the total surface of the earth. The huge area covered by water on the earth is called the Hydrosphere.
  • There is a narrow zone where we find land, water and air together, in contact with each other. This zone is called the Biosphere. Biosphere contains all forms of life.
Get to know about Major Domains of the Earth (Ncert / Cbse Solutions & Revision Notes), Chapter Summary- The Complex Surface of the Earth, Lithosphere, Hydrosphere, Atmosphere, Biosphere, CBSE / NCERT Revision Notes, CBSE NCERT Class VI (6th) | Social Studies | Geography, CBSE NCERT Solved Question Answer, CBSE NCERT Solution.We can determine the elevation of any piece of land by measuring its elevation from the level of the sea.


The Lithosphere

Lithosphere is the solid part that forms the outermost shell of the earth. It is made up of rocks and thin layers of soil that sustain organisms.

There are high mountain ranges, plains and plateaus and deep valleys that form the ocean floor. But, the level of water in the oceans remains the same everywhere. This level is referred to as the sea level.

Mt. Everest is the highest mountain peak on the earth. New Zealander Edmund Hillary and Tenzing Norgay from Nepal were the first climbers to reach the peak of Mt. Everest in 1953.

The Mariana Trench in the Pacific Ocean has the greatest depth found on the earth.The depth of the deepest point in the sea exceeds the height of the highest peak on the Earth. The sea level is considered to be zero. The elevation of land is then measured keeping the sea level as reference.

Almost two-third of the earth’s surface is occupied by huge water bodies that are connected to each other called oceans. The remaining one-third of the earth’s surface has large land masses called the continents.

There are in all seven major continents. They are Asia, Europe, Africa, North America, South America, Australia and Antarctica.

The earth is divided into four hemispheres: Northern, Southern, Western and Eastern.
Most of the landmasses lie in the Northern Hemisphere while most of the Southern Hemisphere is occupied by water.

The Northern Hemisphere is called the Land Hemisphere and the Southern Hemisphere is called the water hemisphere. Asia is the largest continent on the earth. It covers about one-third of the total land area of the earth.

The world’s largest hot desert—the Sahara Desert is located on this continent!

The world’s longest river—the Nile, also flows through Africa.

Antarctica is permanently covered by thick sheets of ice and is known as the Frozen Continent. The first Indian expedition was sent to Antarctica in 1981.

The Hydrosphere

Water occupies more than 71% of the earth’s surface and is present in the oceans, rivers and lakes ice in glaciers, underground water and water vapour in the air. All the water present on the earth’s surface together forms the hydrosphere.

More than 97% of water is in the oceans and seas. Ocean water contains large quantities of dissolved salts and is not fit for drinking. A little less than 3% of water is in the form of glaciers. Only 0.03 per cent of water is available as fresh water.

Oceans form a major portion of the earth’s hydrosphere. The major oceans found on the earth’s surface are Pacific ocean, Atlantic ocean, Indian Ocean and the Arctic ocean. The three main movements of water are waves, tides and ocean currents.

An important fact to note is that all the oceans are interconnected. The Pacific Ocean is the largest of all the oceans and covers one-third of the earth’s surface. It is surrounded by the continents Asia, Australia, North America, and South America.

The Atlantic Ocean is the second largest. It has the continents of North and South America on the western side and Europe and Africa on the eastern side. The Indian Ocean, it is named after our country India and is triangular in shape. It has the continents of Asia on the north, Africa on the west and Australia on the east.

The Arctic Ocean is the smallest ocean and surrounds the North Pole. It is connected to the Pacific Ocean by a narrow stretch of shallow water known as the Bering Strait.

Atmosphere

Water occupies more than 71% of the earth’s surface and is present in the oceans, rivers and lakes ice in glaciers, underground water and water vapour in the air. All the water present on the earth’s surface together forms the hydrosphere.

More than 97% of water is in the oceans and seas. Ocean water contains large quantities of dissolved salts and is not fit for drinking. A little less than 3% of water is in the form of glaciers. Only 0.03 per cent of water is available as fresh water.

Oceans form a major portion of the earth’s hydrosphere. The major oceans found on the earth’s surface are Pacific ocean, Atlantic ocean, Indian Ocean and the Arctic ocean. The three main movements of water are waves, tides and ocean currents.

An important fact to note is that all the oceans are interconnected. The Pacific Ocean is the largest of all the oceans and covers one-third of the earth’s surface. It is surrounded by the continents Asia, Australia, North America, and South America.

The Atlantic Ocean is the second largest. It has the continents of North and South America on the western side and Europe and Africa on the eastern side. The Indian Ocean, it is named after our country India and is triangular in shape. It has the continents of Asia on the north, Africa on the west and Australia on the east.

The Arctic Ocean is the smallest ocean and surrounds the North Pole. It is connected to the Pacific Ocean by a narrow stretch of shallow water known as the Bering Strait.

Biosphere

The earth is made up of land, water and air. These form three domains of the earth—the lithosphere, the hydrosphere, and the atmosphere. All these three domains combine to form the life-giving domain of the earth, called the Biosphere. The biosphere is the narrow zone of contact between land, water, and air where life exists.

The biosphere is divided into the plant kingdom and the animal kingdom. Living organisms on the Earth are broadly classified as plant and animals. All the living organisms are linked to each other, and to the Biosphere.

Humans affect the balance of the biosphere by:
  • Gases and smoke emitted from factories and vehicles are released in the air. The quantity of gases like carbon monoxide, dust and smoke has increased in the air, leading to air pollution.
  • Waste water and chemicals from residences and factories are disposed in rivers, lakes and ponds. This has resulted in water pollution.
Human activities have also affected our natural resources:
  • Reckless cutting down of forests and clearing green areas for construction and agricultural purposes has resulted in land pollution.
  • Less trees means less oxygen and more carbon dioxide in the air. More carbon dioxide has resulted in global warming.

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