NCERT CLASS-6 GEOGRAPHY
CHAPTER-5 [MAJOR LANDFORMS OF THE EARTH]
- Landforms are a result of two processes.
= within the earth continuous movement is taking place.
- The 1st or the internal process leads to the super lift net and sinking of the earth’s surface at several places.
- A hill is a land surface that rises higher than the surrounding area.
= generally, a steep hill with an elevation of more than 600m is termed as mountain.
- The 2nd or the external process is the continuous wearing down and rebuilding of the land surface.
- The wearing away of the earth’s surface is called erosion.
- Different landforms depending on elevation and slope- mountains, plateaus and plains.
- Mountain is any natural elevation of the earth surface.
= may have a small summit and a broad base.
- In some mountains, there are permanently frozen rivers of ice, called glaciers.
- Some mountains are under sea.
- Mountains arranged in line known as range.
- Many mountain systems consist of a series of parallel ranges extending over 100s of kms.
- The Himalayas- Asia, the Alps- Europe, the Andes- South America are mountains ranges.
- There are 3 types of mountains- folds mountains, block mountains, and the volcanic mountains.
- The Himalayan Mountains and the Alps are young fold mountains with rugged relief and high conical peaks.
- The Aravali range in India is one of the oldest fold mountain systems in the world.
- The Appalachians in North America and Ural Mountains in Russia have rounded features and low elevation; very old fold mountains.
- Block mountains are created when large areas are broken and displaced vertically.
= The uplifted blocks are termed as Horsts and the lowered blocks are called graben.
= the Rhine Valley and the Vosges Mountain in Europe are example of such mountains systems.
- Volcanic mountains are formed due to volcanic activity.
= Mt. Kilimanjaro in Africa and Mt. Fujiyama in japan are examples of such mountains.
- Mountains are a store house of water.
- Rivers have their source in the glaciers in the mountains.
- The river valleys and terraces are ideal for cultivation of crops.
- Mountains have a rich variety of flora and fauna.
- A plateau is an elevated flat land.
= it is a flat- topped table lad standing above the surrounding area.
= May have one or more sides with steep slopes.
= height varies from few hundred metres to several thousand metres.
- Deccan plateau is one of the oldest plateaus.
- The East African Plateau in Kenya, Tanzania and Uganda and the Western plateau of Australia.
- The Tibet plateau is the highest plateau in the world with a height of 4000m to 6000m above the mean sea level.
= Plateaus are rich in mineral deposits.
= Many of the mining areas in the world are located in the plateau areas.
= The African plateau is famous for gold and diamond mining.
= In India huge reserves of iron, coal and manganese are found in Chhotanagpur Plateau.
= There may be several waterfalls as the river falls from great heights.
- In India, the Hundru falls in the Chhotanagpur plateau on the river Subarnarekha and the Jog falls in the Karnataka are examples.
- The lava plateaus are rich in black soil, fertile, good for cultivation.
- Plains are large stretches of flat land.
= Not more than 200m above mean sea level.
= Most of the plains are formed by rivers and their tributaries.
- Plains are very fertile.
= Some of the largest plains made by the rivers are found in Asia and North America.
= In Asia, plains formed by Ganga and Brahmaputra in India and Yangtze in china.
= In India, the Indo - Gangetic plains are the most densely populated regions of the country.