(Geography) Chapter 6: Major landforms of the Earth

Mountains 
        A mountain is a high landmass with sharply sloping surfaces. It is considerably higher than the surrounding areas. There is seldom a single mountain. They usually occur in chains or ranges extending over hundreds of kilometres.

  •    There are three types of mountains – Fold Mountains, Block Mountains and Volcanic Mountains.

       Fold Mountains – are created due to the internal movements in the earth. As a result of the cooling and contracting of the molten magma, the crust at several places -becomes eroded and fold are made.

      Block  Mountains – are created when large masses of  land are broken and displaced vertically.  The Rhine valley and the Vosges mountain are example of such a system of the change of land-mass.

      Volcanic Mountains are formed due to volcanic activity. Mt. Kilimanjaro in Africa and Mount Fujiyama in Japan are some examples of volcanic mountains.

How mountains are useful
    Mountain are great tourist place and ideal for resorts, They are places for leisure, Some people like to ski; others like to do rock climbing. Some people visit the mountain just to enjoy the weather and admire it scenic beauty.

    Mountains help in the condensation of moisture and bring about rainfall. They also act as barriers against cold and hot winds.

    Mountains are a store-house of fresh water. Many river have their sources in mountain glaciers, for example the Ganga originates in the Gangotri glacier.

    Dam are built in mountainous areas and reservoirs are made to generate hydroelectricity. This water is also used for irrigation and for domestic and industrial purposes.

    Mountain slopes are terraced for farming. The forest slope provide rich pastures, fuel, fodder and other products.

Plateaus 
    A plateau is a broad and more or less level stretch of upland that rises sharply above the neighbouring lowland. It is also called a tableland.

   The Tibet Plateau is the highest in the world. It is, therefore, called 'the Roof of the World'.

Types of Platean
    Plateaus can be classified  as (i) Intermontane (ii) Continental and (iii) Lava plateaus.
    Intermontane plateaus are partly or completely enclosed by mountains. The plateau of Tibet is the highest intermontane plateau in the world. Other examples are the Mexican plateau, the Columbia plateau in North America and the plateau of Bolivia in the        Andes.
    Continental plateaus are extensive plateaus that rise abruptly from the coastal areas. The plateau region of South Africa and the Indian Peninsula are example of this kind.
    Lava plateaus are formed by lava that comes out from fissures and get deposited over extensive area for millions of years. The Deccan Plateau of India, and the Columbia Plateau in USA are examples of this type.

How Plateaus are useful
    The plateau regions are very rich in minerals. The African plateau areas are famous for gold and diamond mines. The Chhota Nagpur plateau in India has vast resources of iron, coal and manganese. Lava plateaus have fertile soil and are used for farming.        The Deccan plateau has black soil which is good for cotton cultivation. The grasslands covering some plateau are extensively used for livestock rearing.

Plains 
    The relatively flat and low-lying vast expanse of land is called a plain. While some plains are extremely level, others may be rolling or undulating. Most of these plains are formed by major rivers and their tributatries which have been  bringing and depositing        silt, stones and sand along their course for ages together. The great Northern plain of India is formed by the deposits brought by the river Ganga and her tributaries. The Hwang-Ho Plain in China and the Nile Valley Plain in Egypt are also formed by the rivers.

How Plains are useful
    People find plains useful for a wide range of activities. The soil is fertile here. The gentle slopes and valley floors have the earth's most important farmlands. Some of these valuable farmlands include the North European Plains, the Ganga-Brahmaputra Plain      of India and the North China Plain. Plain and valleys are also places for settlements with sprawling town and cities facilitating farming and industrial activities. Communication is smooth as construction of road and railways is easy here. This is the reason that      plains are thickly populated.

                         Key Words
GLACIER :         A slowly-moving river of ice on land.
HILL :                 A raised area or mound of land.
FAULT LINE :    The place where two tectonic plates meet forming a weak line.
HORST :            A block of high ground that stands out because it is flanked by faults on two Sides.
GRABEN :         The portion of the earth's crust, bounded on at least two sides by faults, that has subsidised.