IAS Prelims(GS) preparation 2018
Day # 12 (April 4, 2017)
Topics of the day: Geography 6th NCERT chapter 5 and 6 key points
Chapter 5
- The solid portion of the earth on which we live is called Lithosphere.
- The gaseous layers that surround the earth is the atmosphere.
- Water covers a big area on earth's surface is Hydrosphere.
- The Biosphere is the narrow zone where we find land, water, and air together which contains all forms of life.
- The level of sea water remains same everywhere.
- Elevation of land is measured from the level of sea, which is taken as zero.
- Edmund Hilary and Tenzing Norgay sherpa were first men to climb Mt.Everest on 29th May 1953.
- Junko Tabei of Japan was the first woman to climb Mt.Everest.
- There are 7 major continents:
1. Asia
2. Europe
3. Africa
4. North America
5. South america
6. Australia
7. Antarctica
- Asia is largest continent.
- Asia is separated from Europe by the Ural mountains.
- Africa is the second largest continent.
- Africa is the only continent through which tropic of cancer, the equator and the tropic of cancer passes.
- World's largest hot desert Sahara is located in Africa.
- World's longest river The Nile flows through Africa.
- North America is linked to South America by a very narrow strip of land called the Isthmus of Panama.
- South america has the world's largest river Amazon.
- 71 percent of earth is covered with water.
- More than 97 percent of earth's water is found in the ocean.
- Ocean waters is always moving.
- The five major oceans are -a. the pacific ocean
b. the Atlantic ocean
c. the Arctic ocean
d. The southern ocean
e. the Indian ocean
- Mariana Trench, the deepest part of the earth lies in the pacific ocean.
- Atlantic ocean is S shaped.
- Arctic ocean is connected with the pacific ocean by a narrow stretch of shallow water known as Berring Strait.
- The Atmosphere is divided into five layers based on composition, temperature and other properties. The layers are
the troposphere
the stratosphere
the mesosphere
the thermosphere
the exosphere
- The density of Atmosphere is maximum at the sea level and decreases rapidly as we go up.
- The atmosphere exerts pressure on the earth and it varies from area to area.
- Moving Air is known as wind
- Air moves from high pressure to low pressure.
Chapter 6
- A hill is a land surface that rises higher than the surrounding areas.
- A hill with an elevation of more than 600 metres is termed as mountain.
- Based on elevation and slope we can group different landforms as Mountains, Plains and Plateaus.
- Glaciers are the mountains with permanently frozen rivers of ice.
- Range is the arrangement of mountains in a line.
- There are three types of mountains
1.Fold mountains
2.Block mountains
3.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 the Ural mountains in Russia have rounded features and low elevation. They are 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 examples of such mountain systems.
-Volcanic mountains are formed due to volcanic activity.
-Mt.Kilimanjaro in Africa and Mt.Fujiyama in Japan are examples of such mountains.
-The mountains are a storehouse of water.
-Many rivers have their source in the glaciers in the mountains.
-Water from the mountains is also used for irrigation and generation of hydro-electricity.
-The river valleys and terraces are ideal for cultivation of crops.
-Mountains have a rich variety of flora and fauna.
-Mountains provide an idyllic site for tourists.
-Mauna Kea (Hawaii) in the Pacific Ocean is an undersea mountain. It is higher than Mount Everest being 10,205 metres high.
-The Himalayas, the Alps and the Andes are mountain ranges of Asia, Europe and South America, respectively.
PLATEAUS
-It is an elevated flat land.
-It is a flat-topped table land standing above the surrounding area.
-A plateau may have one or more sides with steep slopes.
-The height of plateaus often varies from few hundred metres to several thousand metres.
-Plateaus, like mountains may be young or old.
-The Deccan plateau in India is one of the oldest plateaus.
-The East African Plateau in Kenya,Tanzania and Uganda and the Western plateau of Australia are other examples.
-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.
-Plateaus are very useful because they are rich in mineral deposits. As a result, 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.
-In the plateau areas, there may be several waterfalls as the river falls from a great height. In India, theHundru falls in the Chhotanagpur plateau on the river Subarnarekha and the Jog
falls in Karnataka are examples of such waterfalls.
-The lava plateaus are rich in black soil that are fertile and good for cultivation.
-Many plateaus have scenic spots and are of great attraction to tourists.
PLAINS
-Plains are large stretches of flat land.
-They are, generally, not more than 200 metres above mean sea level.
-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. It is from these deposits that plains are formed.
-Generally, plains are very fertile.
-These plains are very thickly-populated regions of the world. Plains are the most useful areas for human habitation. There is great concentration of people as more flat land is available for
building houses, as well as for cultivation.
-In India, the Indo-Gangetic plains are the most densely populated regions of the country.