Objectives, Mountains, Classification of Mountains, The Economic Significance of Mountains

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  • The landforms found on the earth’s surface are the result of interplay between internal and external forces. The softer rocks are easily worn down by these forces. While the harder rocks are not so easily worn down. The internal forces are perpetually elevating the earth’s surface and the external forces are constantly wearing down such elevations to make the surface, level.

  • These landforms are not only the physical features of the earth’s surface but also the basis of human civilization. The major landforms found on the earth’s surface are mountains, plateaus, and plains. We will now study the major landforms of the earth and their economic importance for us.

Objectives

The major objectives of this chapter are:

  • To differentiate among the three major landforms found on the earth’s surface

  • To explain the process of formation of various landforms with the help of diagrams

  • To classify mountains on the basis of their mode of formation

  • To discuss the usefulness of mountains to human

  • To list different types of plateaus and define their economic significance

  • To enumerate major types of plains and explain their influence on human life

Mountains

  • Mountains are uplifted portions of the earth’s surface which are much higher in contrast to the surrounding areas. But all the uplifted or elevated areas are not mountains. In fact, height and slope together give rise to a particular form of land which we identify as a landform. For instance, the elevated portion in Tibet, which is about 4500 metres high above sea level, is termed a plateau not a mountain.

  • The formation of a mountain range takes millions of years. During these years, the internal forces of the earth uplifting the land are fighting against erosion wearing it down. Thus, mountains are those uplifted portions of the earth’s surface which have steep slopes and small summit area rising more than thousand metres above the sea level. Mountains have the maximum difference of height between their high and low portions. About 27% of the earth’s surface is covered by the mountains.

Classification of Mountains

On the basis of their mode of formation, the mountains have been classified as:

  • Fold Mountains: Mountain range mainly consisting of uplifted folded sedimentary rocks are known as fold mountains. When these rocks are subjected to horizontal compressional forces for millions of years, they get bent into up and down folds. This leads to the formation of anticlines and synclines.

    • The Himalayas in Asia, the Alps in Europe, the Rockies in North America, and the Andes in South America are the most prominent fold mountains of the world. Since these mountain ranges were formed during the most recent mountain building period, they are known as young fold mountains.

  • Block Mountains: Block mountains are formed by the internal earth movements. When the forces of tension act on the rocks, they create faults in them. When the land between two almost parallel faults is raised above the adjoining areas, it forms a block mountain. It may also occur when the land on the outer side of the faults slips down leaving a raised block between them. Block mountain is also called horst. The Vosges in France, Black Forest Mountains in Germany, and Sierra Nevada in North America are examples of block mountains.

Rift Valley and Block Mountain

Rift Valley and Block Mountain

  • Volcanic Mountains: Due to high temperature deep inside the earth, the rocks turn into a molten magma. When this molten rock material is ejected to the earth’s surface during volcanic eruption, it accumulates around the vent and may take the form of a cone. The height of this cone increases with each eruption and it takes the form of a mountain. As these mountains are formed by the accumulation of volcanic material, they are called volcanic mountains or mountains of accumulation. Mount Mauna Loa in Hawaii Islands, Mount Popa in Myanmar, Vesuvius in Italy, Cotopaxi in Equador, and Fuji Yama in Japan are examples of volcanic mountains.

  • Residual Mountains: The process of weathering and different agents of erosion including rivers, winds, and glaciers are constantly acting on the earth’s crust. The process of wearing down depends on the shape and structure of the rocks to a large extent. After thousands of years, soft rocks are worn down into sand and the hard rocks are left standing up in the area that has been reduced in height. These are called residual mountains. The hills of the Nilgiris, the Parasnath, the Rajmahal, and the Aravalis in India are examples of residual mountains.

The Economic Significance of Mountains

Mountains are very useful to us in the following ways:

  • Storehouse of Resources: Mountains are storehouse of natural resources. Large resources of minerals are found in mountains. The Appalachian range in the United States is famous for coal and limestone deposits. We get timber, lac, medicinal herbs, and wood for making pulp from forests of the mountains. Tea and coffee plantations and some fruits orchards have been developed on the mountain and hill slopes.

  • Generation of Hydroelectricity: Hydroelectricity is generated from the waters of perennial rivers in the mountain regions. The mountainous countries such as Japan, Italy, and Switzerland, which suffer from the shortage of coal have developed hydroelectricity.

  • Abundant Sources of Water: Perennial rivers rising in the snow fed or heavily rain fed mountains are an important source of water. They help in promoting the irrigation and provide water for several other uses.

  • Formation of Fertile Plains: The rivers that originate in the high mountain region bring silt along with water to lower valleys. This helps in the formation of fertile plains. The great alluvial plain of northern India has been formed by the sediments brought down by the rivers Ganga, Sutlej, and the Brahmaputra.

  • Natural Political Frontiers: Mountain ranges do act as natural political frontiers between countries and protect them from invasions to some extent. The Himalaya have formed a political frontier between India and China.

  • Effect on Climate: Mountainous areas have lower temperatures. They serve as climatic divide between two adjoining regions. For example, the Himalaya forms a barrier to the movement of cold winds from Central Asia towards the Indian subcontinent. It also forces the South West Monsoons to ascend and cause rainfall on its southern slopes.

  • Tourist Centres: The pleasant climate and the beautiful scenery of the mountains have led to their development as the centres of tourist attraction. Shimla, Nainital, Mussorie, and Srinagar are some of the important hill stations of India which attract tourists from all over the world.

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