These DAV Class 6 SST Notes and DAV Class 6 SST Chapter 5 Notes – The Realms of the Earth hold significant importance as study material for students.
The Realms of the Earth Class 6 DAV Notes
→ The earth is the only planet which consists of land, air and water as the major physical elements. Each element has its own realm.
→ The earth is divided into four realms- the lithosphere, the hydrosphere, the atomosphere and the biosphere.
→ Lithosphere refers to the solid portion of the earth where we live. It is found in the continents as well as on ocean floors.
→ Continents are large landmasses of the earth. They are seven in number- Asia, Africa, Europe, North America, South America, Australia and Antarctica.
→ Asia is the largest continent while Australia is the smallest continent. Antarctica is permanently covered with thick ice sheets. It is not suitable for human settlement.
→ The surface of the earth is not uniform everywhere. Mountains, plateaus and plains are major landforms of the earth.
→ A mountain or a hill is an uplifted portion of the land surface. Most of the mountains are arranged in a line called a range. There are old mountains as well as young mountains. The Aravalli range in India is the example of old mountain and the Himalayas in Asia are young mountains.
→ A plateau is an elevated flat land. The average height of a plateau is 600 metres above sea level. Most of the plateaus are the storehouses of minerals.
→ A plain is a relatively low-lying flat land. The slope of a plain is gentle and its average height is between 100 and 200 metres above sea-level. Most of the plains in the world have been formed by rivers. They are densely populated as they have fertile soil and an ideal climate.
→ Atmosphere is the vast expanse of air surrounding the earth on all sides. It is held with the earth by the gravitational force. It contains gases like nitrogen, oxygen, carbon dioxide, ozone, hydrogen, etc. Besides the gases, water vapour and particles of dust are also present in the atmosphere.
→ Hydrosphere refers to the water bodies that exist on the earth’s surface. Water covers about two-thirds of the total surface of the earth.
→ The largest part of the earth is covered by oceans. There are four oceans—the Pacific, the Atlantic, the Indian and the Arctic Ocean. The Pacific Ocean is the largest one which covers about one-third of the earth’s surface. The Arctic Ocean remains frozen for a larger part of the year.
→ Biosphere is the narrow zone where we find land, water and air together. Life exists here. It comprises of all forms of organisms. From tiny microbes and bacteria to huge mammals are found in the biosphere. There is a close link between all these organisms including human beings.
→ Continent: A large landmass.
→ Mountain: An uplifted portion of the land surface.
→ Plateau: An upland with rugged surface Plain: A relatively low-lying flai land.
→ Ocean: A huge water body.
→ Atmosphere: Trie vast expanse of air that surround the earth on all sides.
→ Lithosphere :Tne solid portion of the earth on which we live.
→ Biosphere: A narrow zone where land, water and air together are found.
→ Interdependent: Depending on one another for survival or existence.
→ Isthmus : It is a narrow strip of land that joins two large areas of land. It is always surrounded by sea on eithei side.
→ Ozone layer : ‘I he layer present in stratosphere around 15 to 30 km above the earth’s surface. This layer protects earth from harmful ultraviolet radiation of the sun.
→ Sea level: The level of the surface of the sea with respect to the land. It is taken as a mean level between high and low tide, arid used as a standard base for measuring heights and depths.