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Northern Mountains

The fold mountain system in the extra-peninsular part of India consists of the Himalayas and the north-eastern hilly regions. The plate tectonic theory explains the formation of the Himalayan mountains. The earth’s crust is fragmented into tectonic plates by convection currents originating from the earth’s interior. These currents are formed due to the internal heating of the molten rocks under high pressure and temperature. The earth’s crust consists of seven major plates such as the South American plate, North American plate, Pacific plate, Eurasian plate, Indo-Australian plate, African plate and the Antarctic plate. There are about 40 minor plates. These plates may move towards each other and collide along the convergent plate boundaries. Tectonic activities like earthquakes and folding of the earth’s crust occur along the boundaries of the colliding plates, resulting in the formation of fold mountains. The Himalayas were formed by upliftment of the sediments of the Tethys sea in several phases of the convergence of the Eurasian and Indo-Australian plates.

When two plates drift away from each other, these divergent plates result in the opening up of gap in between them. The sea floors spread (as happened in the Atlantic Ocean), along with volcanic activities.

In ancient times, the earth’s surface consisted of a massive landmass called ‘Pangea’. The ancient sea, called Panthalassa, surrounded the super-continent of Pangea. The northern part of the Pangea was known as the ‘Angara Land’, and the southern part was called ‘Gondwanaland’. Gondwanaland was fragmented into several plates due to severe tectonic activities. These plates drifted apart to form South America, Antarctica, Southern part of Africa (South Africa and Madagascar), Southern part of Asia (Arabia, Peninsular India and Malaya), and Australia.



The Himalayas extend from Kashmir in the west to Arunachal Pradesh in the east for a distance of 2400 km. They form the highest mountain system of the world. The highest peak of the Himalayas is the Mount Everest (8848 m) in Nepal. They are young fold mountains which originated from the Tethys sea by a series of upliftments due to different stages of continental drift of the Gondwana landmass. The Himalayas are still unstable and prone to earthquakes.

The Himalayas consist of three parallel ranges, each with characteristic orographic features.


Outer Himalayas or Siwaliks in the south: 
The Siwaliks are the foothills of the Himalayas. They were formed by deposition of alluvium by the mountain streams which come down the slopes. They comprise a series of parallel ridges and structural valleys, rising to a maximum height of 1500 m. In between the parallel ridges lie narrow plains called duns, e.g. Dehradun.


Lesser Himalayas or Himachal in the middle: 
The Lesser Himalayas are situated in between the Siwaliks in the south and Greater Himalayas in the north, rising to a maximum elevation of 4500–5000 m. 

This range consists of parallel ranges, some of which are covered by snow. Important mountain ranges are Pir Panjal, Dhauladhar, Mahabharat and Mussoorie ranges. Picturesque valleys such as the Kashmir valley, Kulu valley, Kangra valley, Lahul valley are renowned for attracting tourists. Hill stations in these ranges are Darjeeling, Shimla, Ranikhet and Nainital.


Greater Himalayas or Himadri in the north: 
The highest range of the Himalayas, with an average altitude of 6000 m, the Himadri range extends from Nanga Parbat in the west to Namcha Barwa in the east. These mountain ranges rise above the limit of perpetual snow. The highest peak of the world, Mount Everest (8848 m), is located in Nepal (known as Sagarmatha in Nepal). Kanchanjunga (8598 m), Nandadevi, Makalu, Manaslu, Dhaulagiri, Gowrishankar, Nanga Parbat are some of the highest peaks of the world, situated on this range. K2 or Godwin Austin (8611 m) in the Karakoram Range is the highest peak of India. The Himadri range is the home of many glaciers. The Gangotri glacier (the source of river Ganges) and the Yamunotri glacier are some examples. There are several major mountain passes such as the Shipki La, Jelep La and Nathu La on this range.


North-eastern Hilly Region or Purvanchal: 

The hills and plateaus of Manipur, Nagaland, Mizoram, Tripura, Meghalaya, Assam and Arunachal Pradesh are collectively called Purvanchal. They constitute the eastern limit of the Greater Himalayas, with an average altitude of 2000–3000 m. The Patkai Bum range, Mishmi hills, Barail range, Naga hills, Mizo hills are aligned in parallel north-south trending ranges. The Meghalaya Plateau is part of the Gondwana landmass. The Meghalaya Plateau consists of the Garo, Khasi and Jaintia hills, on which is situated the Shillong plateau.


Importance of the Himalayas on the Economic Life of Indians

  • Himalayas intercept the Monsoon winds and cause rainfall over the greater part of the country.
  • Major north Indian rivers owe their origin to the glaciers of the high Himalaya.
  • The vast Indo-Gangetic plains have been formed by the deposition of sediments brought down by the Indus, Ganga, Brahmaputra and their innumerable tributaries.
  • The Himalayan forests support a number of forest-based economic activities like timber trade.
  • Development of tourism industry is a major economic activity in the Himalayas.
  • Himalayas provide favourable terrain for development of hydro-electricity.
  • Cultivation of orchard crops like apples and oranges and cultivation of crops like tea and saffron are the major economic activities in the Himalayas.
  • Many medicinal plants and herbs grow in these mountains.

North Indian Plains

The great plains of North India, covering an area of 6,52,000 sq. km, stretches in an east-west direction. They are bordered by the Himalayas in the north and Central Indian Highlands in the south. These plains consist of very rich and fertile alluvium deposited by many perennial rivers, such as Indus, Ganga, Brahmaputra and their numerous tributaries. The plains form one of the largest agricultural belts in the world. The Northern Plains provide suitable conditions for irrigation, inland navigation, constructing roads and railways. These have helped in setting up industries. About 40 per cent of India’s population resides in the northern plains.

There are four sections of the plains.

  1. Ganga plains
    1. Upper Ganga plain—the land between the Ganga and Yamuna is called the Ganga–Yamuna doab (meaning land between two rivers), which lies in Uttar Pradesh.
    2. Middle Ganga plain—plains of Bihar
    3. Lower Ganga plain—plains of West Bengal, ending at the Ganga delta in Sundarbans.
  2. Punjab plains—plains of Punjab and Haryana, gradually merge with the Rajasthan plains.
  3. Rajasthan plains—Lying to the west of the Aravalli Hills, the Rajasthan Plains consist of
    1. Rajasthan–Bagar
    2. Marusthali–consisting of the Thar desert. Luni is the only river of significance in this desert region. Sand dunes are found on the desert surface. The crescent-shaped sand dunes are called barchans.
  4. Brahmaputra valley––known as the Assam valley.

Peninsular Plateau is a part of the ancient Gondwanaland. The northern part of the Peninsular Plateau, lying to the north of the Narmada river and formed mainly by the Malwa Plateau, is known as the Central Indian Highlands. The Deccan Plateau lies in the Indian peninsula.

Central Indian Highlands

Wide tracts of hilly country separate the Great Plains of North India from the Peninsular Plateau and coastal plains. The Central Indian Highlands are large tracts of rugged hills and plateaus, lying between the Aravalli range in the west to the Bundelkhand and Baghelkhand uplands in the east. Malwa Plateau and the Chotanagpur Plateau are significant parts of these highlands. The Aravalli range forms the oldest fold mountain of the world. Its highest peak is the Mount Guru Shikhar (1722 m). Mount Abu is a famous hill station. The east Rajasthan Upland, Madhya Bharat Pathar and Vindhyan Uplands are other features of the Central Indian Highlands. The Narmada and Tapi rivers arise from these highlands, and flow westward into the Arabian Sea through ancient rift valleys. The Chambal River forms significant badland topography while flowing through the region. Much of the area remains forested.

Deccan Plateau

The Deccan Plateau is bordered by the Satpura–Mahadeo–Maikal ranges and Rajmahal hills in the north, Eastern Ghats in the east and Western Ghats in the west. They are part of the Gondwanaland landmass and comprise ancient crystalline Pre-Cambrian rocks. The northwestern part of the Deccan Plateau is covered by basaltic rocks. Due to differential weathering and erosion, the basaltic rocks have formed flat-topped hills with steep escarpments which descend down in step-like formation towards the east. This is called the ‘Deccan Trap’ (Trap meaning steps) and covers almost entirely the state of Maharashtra. The soil is black in colour and is very important for the cultivation of cotton.

The Narmada and Tapti rivers flow through rift valleys along the northern boundary of the peninsular plateau. The Western Ghats, called Sahyadris, border the western border of the peninsular plateau. Kalsubai is the highest peak of the Western Ghats. The Western Ghats are almost continuous with only three passes or gaps which interrupt their continuity. They are the Thal Ghat and Bhor Ghat passes in Maharashtra, and the Pal Ghat gap in Kerala. The Eastern Ghats, called Malayadris, border the eastern part of the peninsular plateau. They are not as continuous as the Western Ghats and are dissected by the major east-flowing rivers like Mahanadi, Godavari, Krishna and Cauvery. Mahendragiri is a major peak. The Western Ghats meet the Eastern Ghats in the Nilgiri hills, which continue southwards as the Anaimalai range, Cardamom and Palni hills. Dodda Betta is the highest peak of the Nilgiris. Anaimudi in the Anaimalai range is the highest peak of South India. Hill stations in the Western Ghats are Mahabaleshwar and Matheran. Ooty (Ootacamund) in the Nilgiri hills, Pachmarhi in the Mahadeo hills are also famous.


The peninsular plateau is economically important as:

  • There are rich deposits of various mineral resources.
  • The rivers coming along the edge of the plateaus form waterfalls. This helps in the generation of hydro-electric power.
  • The soil is suitable for cultivation of cotton.
  • The dense forests have rich wildlife.

Coastal Plains

India’s coastline extends from the Kutch in Gujarat in the west to the Gangetic delta in the east.

The Western coastal plain lies between the Western Ghats and Arabian Sea. It extends from Gulf of Kutch in the north to Cape Comorin (Kanyakumari) in the south. The length of the western coastal plain is 1500 km. The subdivisions of the Western coastal plain are the Kutch and Kathiawar peninsulas and the Gujarat coastal plain (in Gujarat), Konkan coastal plain (in Maharashtra and Goa), Karnataka coastal plain (in Karnataka) and Malabar coastal plain (in Kerala). The Malabar coastal plain is the widest part of the western coast, made up of extremely fertile alluvial soil and has a number of lagoons and backwaters like Asthamudi and Vembanad. The western coast receives heavy rainfall from the south-west monsoon winds.

The Eastern coastal plain extends from the Gangetic delta to Cape Comorin (Kanyakumari) and lies between the Eastern Ghats and Bay of Bengal. The eastern coastal plain consists of the deltas of Mahanadi, Godavari, Krishna and Kaveri. Some salt water lagoons and lakes are present, such as the Chilka Lake in Odisha (largest lagoon in India) and Pulicat Lake in Tamil Nadu. The eastern coast is divided into the Coromandel Coast in the south and Utkal coast in the north. The Northern Circars extend from the mouth of the river Subarnarekha to the Krishna delta.

Importance of the Coastal Regions of India

  • Economic activities such as agriculture, trade, tourism, industrial development, fishing and salt making.
  • Important hinterland for major parts like Kandla, Mumbai, Nhava-Sheva, Mormugao, Mangalore, Cochin, Tuticorin, Chennai, Visakhapatnam, Paradeep, Haldia, Kolkata.

Islands of India

There are 247 islands in India, out of which 204 islands are in the Bay of Bengal and the rest are in Arabian Sea and Gulf of Mannar (between India and Sri Lanka).

The Andaman and Nicobar islands in the Bay of Bengal are crests of submerged fold mountains and are made of hard volcanic rocks. The Andamans consist of three main islands––North, Middle and South Andamans, collectively known as the Great Andamans. The Middle Andaman is the largest island of the Andamans. The Nicobar group consists of 19 islands. Great Nicobar is the largest amongst them. Indira Point, the southernmost tip of India, is in the Greater Nicobar Island. Barren Island and Narcondam Island in this group are of volcanic origin. The Barren Island volcano is an active volcano.

The islands of Arabian Sea are formed of corals. Lakshadweep, Amindivi and Minicoy are the major islands.

Pamban Island is situated between India and Sri Lanka.

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