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1, , CHAPTER 2, STRUCTURE AND PHYSIOGRAPHY, , KSK, , 1
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2, , Based on the variations in its geological structure, and formations, India can be divided into three, geological divisions. These geological regions, broadly follow the physical features:, , KSK, , 2
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4, , THE PENINSULAR BLOCK, , KSK, , 4
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5, , THE PENINSULAR BLOCK, The northern boundary of the Peninsular, Block may be taken as an irregular line, running from Kachchh along the western flank, of the Aravali Range near Delhi and then, roughly parallel to the Yamuna and the Ganga, as far as the Rajmahal Hills and the Ganga, delta., KSK, , 5
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7, , The Peninsula is formed essentially by a, great complex of very ancient gneisses and, granites, , KSK, , 7
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8, , As a part ofthe Indo-Australian Plate, it has been, subjected to various vertical movements and, block faulting. The rift valleys of the Narmada,, the Tapi and the Mahanadi and the Satpura, block mountains are some examples of it., , KSK, , 8
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12, , Most of the east flowing rivers form deltas, before entering into the Bay of Bengal., The Mahanadi,, The Krishna,, The Kaveri and, The Godavari, , KSK, , 12
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13, , THE HIMALAYAS AND OTHER, PENINSULAR MOUNTAINS, The Himalayas along with other Peninsular, mountains are young, weak and flexible in their, geological structure unlike the rigid and stable, Peninsular Block., , KSK, , 13
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15, , Consequently, they are still, subjected to the interplay of exogenic and, endogenic forces, resulting in the development, of faults, folds and thrust plains., , KSK, , 15
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16, , These mountains are tectonic in origin, dissected, by fast-flowing rivers which are in their youthful, stage. Various landforms like gorges, V-shaped, valleys, rapids, waterfalls, etc. are indicative of, this stage., , KSK, , 16
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17, , INDO -GANGA -BRAHMAPUTRA PLAIN, , The third geological division of India, comprises THE PLAINS formed by the river, Indus, the Ganga and the Brahmaputra, , KSK, , 17
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19, , Originally, it was a geo-synclinal depression, which attained its maximum development, during the third phase of the Himalayan, mountain formation approximately about 64, million years ago. Since then, it has been, gradually filled by the sediments brought by, the Himalayan and Peninsular rivers. Average, depth of alluvial deposits in these plains, ranges from 1,000-2,000 m., KSK, , 19
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20, , PHYSIOGRAPHY, Based on these macro variations, India can, be divided in, to the following physiographic, divitions :, 1 .The Northern and Northeastern Mountains, 2. The Northern Plain, 3. The Peninsular Plateau, 4 .The Indian Desert, 5. The Coastal Plains, 6. The Islands., , KSK, , 20
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21, , 1.The North and Northeastern Mountains, , KSK, , 21
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22, , 1.The North and Northeastern Mountains, The North and Northeastern Mountains consist, of the Himalayas and the Northeastern hills., , KSK, , 22
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23, , The Himalayas consist of a series of parallel, mountain ranges. Some of the important ranges, are, 1. The Greater Himalayan range, which, includes the Great Himalayas and the TransHimalayan range, 2. The Middle Himalayas and, 3. the Shiwalik., KSK, , 23
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24, , The approximate length of the Great Himalayan, range, also known as the central axial range, is, 2,500 km from east to west, and their width, varies between 160-400 km from north to, south, , KSK, , 24
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25, , There are large-scale regional variations, within the Himalayas. On the basis of relief,, alignment of ranges and other geomorphological, features, the Himalayas can be divided into the, following sub-divisions:, , KSK, , 25
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26, , 1. Kashmir or Northwestern Himalayas, 2 .Himachal and Uttaranchal Himalayas, 3 .Darjiling and Sikkim Himalayas, 4 .Arunachal Himalayas, 5 .Eastern Hills and Mountains., KSK, , 26
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28, , 1. Kashmir or Northwestern Himalayas, , KSK, , 28
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29, , 1. Kashmir or Northwestern Himalayas, It comprise a series of ranges such as the, Karakoram, Ladakh, Zaskar and Pir Panjal., Between the Great Himalayas and the Pir Panjal, range, lies the world famous valley of Kashmir, and the famous Dal Lake.Important glaciers of, South Asia such as the Baltoro and Siachen are, also found in this region., , KSK, , 29
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32, , The Kashmir Himalayas are, also famous for Karewas, formations, which are useful, for the cultivation of Zafran,, thick deposits of a local variety of saffron., , KSK, , 32
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45, , Srinagar, capital city of the state of Jammu, and Kashmir is located on the banks of Jhelum, river., , KSK, , 45
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47, , The southernmost part of this region consists, of longitudinal valleys known as ‘duns’. Jammu, dun and Pathankot dun are important examples., , KSK, , 47
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50, , 2. The Himachal and Uttaranchal Himalayas, This part lies approximately between the Ravi, in the west and the Kali (a tributary of, Ghaghara) in the east., The northernmost part of the Himachal, Himalayas is an extension of the Ladakh cold, desert, , KSK, , 50
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53, , The two distinguishing features of this, region from the point of view of physiography, are the ‘Shiwalik’ and ‘Dun formations’. Some, important duns located in this region are the, Chandigarh-Kalka dun, Nalagarh dun, Dehra, Dun, Harike dun and the Kota dun, etc. Dehra, Dun is the largest of all the duns with an, approximate length of 35-45 km and a width, of 22-25 km., KSK, , 53
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56, , The two distinguishing features of this, region from the point of view of physiography, are the ‘Shiwalik’ and ‘Dun formations’., , KSK, , 56
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57, , Chandigarh-Kalka dun, Nalagarh dun, Dehra, Dun, Harike dun and the Kota dun, etc., DEHRA DUN is the largest of all the duns with, an approximate length of 35-45 km and a width, of 22-25 km., , KSK, , 57
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58, , In the Great Himalayan range,, the valleys are mostly inhabited by the, Bhotia’s. These are nomadic groups who, migrate to ‘Bugyals’, , KSK, , 58
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60, , The famous ‘Valley of flowers’ is also situated in, this region., , KSK, , 60
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A scene from Valley of Flowers, Impatiens sulcata, This flower paints, the Valley of Flowers in pink in the first week of August., , KSK https://en.wikipedia.org/wiki/Valley_of_Flowers_National_Park#/media/File:Valley_of_flowers.JPG, , 62, , 62
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69, , 3. The Darjiling and Sikkim Himalayas, * They are flanked by Nepal Himalayas in the, west and Bhutan Himalayas in the east., ➢, , ➢, , KSK, , * It is a region of high mountain peaks like, Kanchenjunga(Kanchengiri), and deep valleys., *The higher reaches of this region are inhabited, by Lepcha tribes, , 69
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71, , In place of the Shiwaliks here, the ‘duar, formations’ are important, which have also been, used for the development of tea gardens., , KSK, , 71
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72, , From wikipedia, The Dooars or Duars (/duˈɑːrz/) are the alluvial, floodplains in northeastern India that lie south of, the outer foothills of the Himalayas and north of, the Brahmaputra River basin. This region is about, 30 km (19 mi) wide and stretches over about 350, km (220 mi) from the Teesta River in West Bengal, to the Dhanshiri River in Assam. The region forms, the gateway to Bhutan.[1] It is part of the TeraiDuar savanna and grasslands ecoregion., , KSK, , 72
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75, , 4. The Arunachal Himalayas, These extend from the east of the Bhutan, Himalayas up to the Diphu pass in the east., , KSK, , 75
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79, , 5 .The Eastern Hills and Mountains, These are part of the Himalayan mountain, system having their general alignment from the, north to the south direction. They are known, by different local names. In the north, they are, known as, Patkai Bum,, Naga hills,, the Manipurhills and, in the south as Mizo or Lushai hills., KSK, , 79
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83, , The physiography of Manipur is unique by, the presence of a large lake known as ‘Loktak’, lake at the centre, surrounded by mountains, from all sides. Mizoram which is also known, as the ‘Molassis basin’ which is made up of, soft unconsolidated deposits, , KSK, , 83
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88, , The Northern Plains, The northern plains are formed by the, alluvial deposits brought by the rivers – the, Indus, the Ganga and the Brahmaputra., These plains extend approximately 3,200 km, from the east to the west. The average width, of these plains varies between 150-300 km., , KSK, , 88
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89, , The maximum depth of alluvium deposits, varies between 1,000-2,000 m. From the, north to the south, these can be divided into, three major zones: the Bhabar, the Tarai and, the alluvial plains. The alluvial plains can be, further divided into the Khadar and the, Bhangar., , KSK, , 89
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90, , Bhabar is a narrow belt ranging between, 8-10 km parallel to the Shiwalik foothills at, the break-up of the slope. As a result of this,, the streams and rivers coming from the, mountains deposit heavy materials of rocks, and boulders, and at times, disappear in this, zone., KSK, , 90
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93, , South of the Bhabar is the Tarai belt,, with an approximate width of 10-20 km where, most of the streams and rivers re-emerge, without having any properly demarcated, channel, thereby, creating marshy and, swampy conditions known as the Tarai., , KSK, , 93
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95, , The south of Tarai is a belt consisting of, old and new alluvial deposits known as the, Bhangar and Khadar respectively., , KSK, , 95
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97, , The mouths of these mighty rivers also form, some of the largest deltas of the world, for, example, the famous Sunderbans delta., , KSK, , 97
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101, , The Peninsular Plateau, Rising from the height of 150 m above the river, plains up to an elevation of 600-900 m is the, irregular triangle known as the Peninsular, plateau., , KSK, , 101
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103, , Delhi ridge in the northwest, (extension, of Aravalis), the Rajmahal hills in the east, Gir, range in the west and the Cardamom hills in, the south constitute the outer extent of the, Peninsular plateau., , KSK, , 103
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104, , The general elevation of the, plateau is from the west to the east, which is, also proved by the pattern of the flow of rivers., , KSK, , 104
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105, , Some of the important physiographic features, of this region are tors, block mountains, rift, valleys, spurs, bare rocky structures, series of, hummocky hills and wall-like quartzite dykes, offering natural sites for water storage., , KSK, , 105
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106, , On the basis of the prominent relief, features, the Peninsular plateau can be divided, into three broad groups:, , KSK, , 106
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107, , (i) The Deccan Plateau, (ii) The Central Highlands, (iii) The Northeastern Plateau., , KSK, , 107
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109, , The Deccan Plateau, This is bordered by the Western Ghats in the, west, Eastern Ghats in the east and the, Satpura, Maikal range and Mahadeo hills in, the north., Western Ghats are locally known, by different names such as Sahyadri in, Maharashtra, Nilgiri hills in Karnataka and, Tamil Nadu and Anaimalai hills and, Cardamom hills in Kerala., KSK, , 109
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112, , ‘Anaimudi’ (2,695 m), the highest peak of, Peninsular plateau is located on the Anaimalai, hills of the Western Ghats followed by Dodabetta, (2,637 m) on the Nilgiri hills., , KSK, , 112
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Western Ghats region has the largest Indian elephant population, in India, , KSK, , credit: https://commons.wikimedia.org/wiki/User:Yathin_sk, , 113, , 113
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116, , The Eastern and the, Western Ghats meet each other at the Nilgiri, hills., , KSK, , 116
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118, , The Central Highlands, They are bounded to the west by the Aravali, range. The Satpura range is formed by a series, of scarped plateaus on the south, generally at, an elevation varying between 600-900 m above, the mean sea level., , KSK, , 118
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122, , The extension of the, Peninsular plateau can be seen as far as, Jaisalmer in the West, where it has been, covered by the longitudinal sand ridges and, crescent-shaped sand dunes called barchans, , KSK, , 122
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124, , This region has undergone metamorphic, processes in its geological history, which can, be corroborated by the presence of, metamorphic rocks such as marble, slate,, gneiss, etc., , KSK, , 124
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125, , The Northeastern Plateau, In fact it is an extension of the main Peninsular, plateau., *The Meghalaya and Karbi Anglong, plateau stand detached from the main, Peninsular Block., , KSK, , 125
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127, , The Indian Desert, To the northwest of the Aravali hills lies the, Great Indian desert. It is a land of undulating, topography dotted with longitudinal dunes, and barchans., , KSK, , 127
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129, , It is believed that during the Mesozoic era, this, region was under the sea., * The Luni river flowing in the southern part of, the desert is of some significance., , KSK, , 129
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130, , The Coastal Plains, On the basis of the location and, active geomorphological processes, it can be, broadly divided into two:, (i) the western coastal plains;, (ii) the eastern coastal plains., , KSK, , 130
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132, , The western coastal plains are an example, of submerged coastal plain., * Because of, this submergence it is a narrow belt and, provides natural conditions for the, development of ports and harbours. Kandla,, Mazagaon, JLN port Navha Sheva, Marmagao,, Mangalore, Cochin, etc. are some of the, important natural ports located along the, west coast., , KSK, , 132
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133, , the western coast may be divided into, following divisions –, the Kachchh and, Kathiawar coast in Gujarat,, Konkan coast in Maharashtra,, Goan coast and, Malabar coast in Karnataka and Kerala respectively., , KSK, , 133
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134, , The Malabar, coast has got certain distinguishing features, in the form of ‘Kayals’ (backwaters), which, are used for fishing, inland navigation and also, due to its special attraction for tourists. Every, year the famous Nehru Trophy Vallamkali, (boat race) is held in Punnamada Kayal in, Kerala., KSK, , 134
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135, , As compared to the western coastal plain,, the eastern coastal plain is broader and is an, example of an emergent coast. There are welldeveloped deltas here, formed by the rivers, flowing eastward in to the Bay of Bengal. These, include the deltas of the Mahanadi, the, Godavari, the Krishna and the Kaveri., KSK, , 135
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136, , The Islands, There are two major island groups in India –, one in the Bay of Bengal and the other in the, Arabian Sea., , KSK, , 136
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137, , The Bay of Bengal island groups, consist of about 572 islands/islets. These are, situated roughly between 6°N-14°N and, 92°E -94°E. The two principal groups of islets, include the Ritchie’s archipelago and the, Labrynth island., , KSK, , 137
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138, , The entire group of island is divided into two, broad categories – the Andaman in the north and, the Nicobar in the south. They are separated by, a water body which is called the Ten degree, channel., , KSK, , 138
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140, , It is believed that these islands are an elevated, portion of submarine mountains. However,, some smaller islands are volcanic in origin., Barren island, the only active volcano in India, is also situated in the Nicobar islands., , KSK, , 140
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Barren Island, a small volcanic island which is part of the Andaman, Island group in the Andaman Sea west of Malayasia, began a new, eruptive phase late in 1994., , KSK, , 141, , 141
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142, , The islands of the Arabian sea include, Lakshadweep and Minicoy. These are scattered, between 8°N-12°N and 71°E -74°E longitude., , KSK, , 142
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146, , The entire island group is built of coral deposits., There are approximately 36 islands of which, 11 are inhabited. Minicoy is the largest island, with an area of 453 sq. km., , KSK, , 146
