MAJOR LANDFORMS OF THE EARTH
CLASS VI CHAPTER 6
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·
The ground we are
standing on is slowly moving. Within the earth, a continuous movement is taking
place. The first, or the internal process leads to the upliftment and sinking
of the earth’s surface at several places.
·
The second, 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. The surface is being lowered by the
process of erosion and rebuilt by the process of deposition.
·
These two processes
are carried out by running water, ice and wind. Broadly, we can group different
landforms depending on elevation and slope as mountains, plateaus and plains.
MOUNTAINS
·
A mountain is any
natural elevation of the earth surface.
·
It is considerably
higher than the surrounding area. Some mountains are even higher
than the clouds. As we go higher, the climate becomes colder.
·
In some mountains,
there are permanently frozen rivers of ice which are called glaciers.
·
Less people live in
the mountain areas because slopes are steep, less land is available for farming.
·
When mountains are
arranged in a line are called range.
· There are three
types of mountains- Fold Mountains, Block Mountains and the Volcanic Mountains.
Fold Mountains
(i)The Himalayan Mountains and the Alps are
young fold mountains with rugged relief and high conical peaks.
(ii)The Aravali range in India is one of the
oldest fold mountain systems in the world.
(iii) The Appalachians in North America and
theUral mountains in Russia are very old
foldmountains.
Block Mountains
(i) Block Mountains are
created when large areas are broken and displaced vertically.
(ii) The uplifted blocks
are termed as horsts and the lowered blocks are called
graben.
(iii) The Rhine valley and
the Vosges mountain in Europe are examples of such mountain systems.
Volcanic mountains
(i)
Volcanic mountains
are formed due to volcanic activity.
(ii)
Mt.Kilimanjaro in
Africa and Mt.Fujiyama in Japan are examples of such mountains.
(iii)
The mountains are a storehouse
of water. Many rivers have their source in the glaciers in the mountains.
(iv) Water from the
mountains is also used for irrigation and generation of hydro-electricity.(v) The river valleys and terraces are ideal for
cultivation of crops. Mountains have a rich variety of flora and fauna.
PLATEAUS
- · A plateau is an elevated flat land. It is a flat-toppedtable land standing above the surrounding area.
- The height of plateaus often varies from few hundred metres to several thousand metres.
- The Deccan plateau in India is one of the oldest plateaus.
- The Tibet plateau is the highest plateau in the world with a height of 4,000 to 6,000 metres above the mean sea level.
- As plateaus are rich in minerals 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 the Chhotanagpur plateau.
- There may be several waterfalls In the plateau areas.
- Example-The Hundru falls in the Chhotanagpur plateau on the river Subarnarekha and the Jog falls in Karnataka.
PLAINS
(i)Plains are
large stretches of flat land.They are, generally, not more than 200 metres
above mean sea level.
(ii)Most of the
plains are formed by rivers and their tributaries. The rivers flow down the
slopes of mountains and erode them. They carry forward the eroded material.
Then they deposit their load consisting of stones, sand and silt along their
courses and in their valleys.
(iii)plains are
fertile and good for construction and transportation. So these areas are very much
populated.
(iv)Example-these
plains are formed by the Ganga and the Brahmaputra in India and
the Yangtze in China.ghj
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