Introduction:

• India is a vast country with varied landforms.
• In fact, our country has practically all major physical features of the earth i.e. mountains, plains, deserts, plateaus and islands.
• We find different types of rocks; some are very hard like marble which has been used for making the Taj Mahal, and some are very soft like soap stone which is used in making talcum powder.
• The colour of soil varies from one place to the other because soil is formed out of different types of rocks.
• Most of these variations are caused due to differences in rock formations.
• India is a large landmass formed during different geological periods which has influenced her relief.
• Besides geological formations, a number of processes such as weathering, erosion and deposition have created and modified the relief to its present form.

Tectonic Plate Theory:

• The tectonic plate theory describes the large scale motion of the earth’s lithosphere.
• This theory is based on continental drift which explains the formation of various continents over millions of years; as we see them today.

Plate Boundaries:

Based on the relative movement between two tectonic plates, there are three types of plate boundaries. They are as follows:

Convergent Boundary: In this case, the two adjacent tectonic plates come towards each other.

Divergent Boundary: In this case, the two adjacent plates move away from each other.

Transform Boundary: In this case, the two adjacent plates move along their borders.

• The movement of these plates has changed the position and size of the continents over millions of years.
• Such movements have also influenced the evolution of the present landform features of India.
• About 225 million years ago, the earth contained a single landmass; called Pangaea.
• That landmass was divided into two landmasses, viz. Laurasia and Gondwana Land; about 200 million years ago.

• As the figures; given here show; the landmasses further broke into different parts and experienced continental drifts at various stages.
• The Gondwana Land included the modern day India, Australia, North America, South America and Antarctica.

Formation of Himalayas:

• The oldest landmass, (the Peninsula part), was a part of the Gondwana land.
• The Gondwana land included India, Australia, South Africa, South America and Antarctica as one single land mass.
• The convectional currents split the crust into a number of pieces, thus leading to the drifting of the Indo-Australian plate after being separated from the Gondwana land, towards north.
• The northward drift resulted in the collision of the plate with the much larger Eurasian Plate.
• Due to this collision, the sedimentary rocks which were accumulated in the geosyncline known as the Tethys were folded to form the mountain system of western Asia and Himalaya.

Formation of India:

• The Indian Peninsula drifted towards the north and finally collided with the much larger Eurasian Plate.
• As a result of this collision, the sedimentary rocks which were accumulated in the geosynclines (known as Tethys) got folded and formed the mountain systems of the West Asia and Himalaya.
• Due to the uplift of the Himalayas in the Tethys Sea, the northern flank of the Indian Peninsula got subsided and formed a large basin.
• That basin was filled with sediments from the rivers which came from the mountains in the north and from the peninsula in the south.
• Thus, an extensive flat land of alluvial soil was formed which is known as the northern plains of India.

Formation of Northern Plains:

• The Himalayan uplift out of the Tethys sea and subsidence of the northern flank of the peninsular plateau resulted in the formation of a large basin.
• In due course of time this depression, gradually got filled with deposition of sediments by the rivers flowing from the mountains in the north and the peninsular plateau in the south.
• A flat land of extensive alluvial deposits led to the formation of the northern plains of India.
• Land of India displays great physical variation - Geologically, the Peninsular Plateau constitutes one of the ancient landmasses on the earth's surface.
• It was supposed to be one of the most stable land blocks.
• The Himalayas and the Northern Plains are the most recent landforms.
• From the view point of geology, Himalayan Mountains form an unstable zone.
• The whole mountain system of Himalaya represents a very youthful topography with high peaks deep valleys and fast flowing rivers.
• The northern plains are formed of alluvial deposits.
• The peninsular plateau is composed of igneous and metamorphic rocks with gently rising hills and wide valleys.

The physical features of India can be grouped under the following physiographic divisions:

1. The Himalayan Mountains or the Northern Mountains
2. The Northern Plains or the Indo-Gangetic Plains
3. The Peninsular Plateau
4. The Great Indian Desert
5. The Coastal Plains
6. The Islands

The Himalayan Mountains:

• Geologically young and structurally Fold Mountains stretch over the northern borders of India.
• Run in a west-east direction from the Indus to the Brahmaputra.
• Represents the tall high and one of the most rugged mountain barriers of the world.
• They form an arc, which covers a distance of about 2,400 Km.
• Their width varies from 400 Km in Kashmir to 150 Km in Arunachal Pradesh.
• The altitudinal variations are greater in the eastern half than those in the western half.
• The Himalayas consist of three parallel ranges in its longitudinal extent.

The Himalayas have three parallel ranges in the longitudinal extent namely:

1. Great or Inner Himalayas also called Himadri
2. Middle Himalayas or Himachal
3. Outer Himalayas or Shiwaliks

The Great or Inner Himalayas:

• The northern most range is known as the Great or Inner Himalayas or the 'Himadri'.
• These mountain ranges run in a west-east direction from the Indus to the Brahmaputra.
• It is the most continuous range consisting of the loftiest peaks with an average height of 6,000 metres.
• It contains all the prominent Himalayan peaks.
• The folds of Great Himalayas are asymmetrical in nature.
• The core of this part of Himalayas is composed granite.
• It is perennially snow bound, and a number of glaciers descend from this range.
• They remain snow-capped throughout the year.

The Lesser Himalaya or Himachal:

• This lies towards the south of the Great Himalayas.
• The altitude of peaks in this range varies from 3,700 m to 4,500 m.
• Average width of this range is 50 km.
• This range is mainly composed of highly compressed and altered rocks.
• While the Pir Panjal range forms the longest and the most important range, the Dhaula Dhar and the Mahabharat ranges are also prominent ones.
• This range consists of the famous valley of Kashmir, the Kangra and Kullu Valley in Himachal Pradesh.
• This region is well-known for its hill stations.

Outer Himalayas or Shiwaliks:

• This is the outermost range of the Himalayas.
• The outer-most range of the Himalayas is called the Shiwaliks.
• They extend over a width of 10-50 Km and have an altitude varying between 900 and 1100 meters.
• These ranges are composed of unconsolidated sediments brought down by rivers from the main Himalayan ranges located farther north.
• These valleys are covered with thick gravel and alluvium.
• The longitudinal valley lying between lesser Himalaya and the Shiwaliks are known as Duns. Dehra Dun, Kotli Dun and Patli Dun are some of the well-known Duns.

Besides the longitudinal divisions, the Himalayas have been divided on the basis of regions from west to east. These divisions have been demarcated by river valleys.

Himalayan Regions from East to West:

1. Punjab Himalayas: This part lies between the Indus and Sutlej. From west to east, this is also known as Kashmir Himalaya and Himachal Himalaya; respectively.
2. Kumaon Himalayas: This part lies between Sutlej and Kali rivers.
3. Nepal Himalayas: This part lies between the Kali and Tista rivers.
4. Assam Himalayas: This part lies between the Tista and Dihang rivers. The Brahmaputra marks the eastern most boundaries of the Himalayas.

Eastern Hills and Mountains: 

• The Brahmaputra marks the eastern-most boundary of the Himalayas.
• Beyond the Dihang gorge, the Himalayas bend sharply to the south and spread along the eastern boundary of India.
• They are known as the Purvachal or the Eastern hills and mountains.
• These hills running through the north-eastern states are mostly composed of strong sandstones, which are sedimentary rocks.
• Covered with dense forests, they mostly run as parallel ranges and valleys.
• The Purvachal comprises the Patkai hills, the Naga Hills, the Manipur hills and the Mizo hills.

The Northern Plains:

• The northern plain of India is formed by three river systems, viz. the Indus, the Ganga and the Brahmaputra; along with their tributaries.
• This plain is composed of alluvial soil which has been deposited over millions of years.
• The total area of the northern plain is about 7 lakh square kilometer.
• It is about 2400 km long and about 240 to 320 km broad, is a densely populated physiographic division, and is agriculturally a very productive part of India.
• The rivers coming from northern mountains are involved in depositional work.
• In the lower course, due to gentle slope, the velocity of the river decreases which results in the formation of Riverine islands.
• The rivers in their lower course split into numerous channels due to the deposition of silt. These channels are known as distributaries.

Do you know?

Majuli, in the Brahmaputra River, is the largest inhabited Riverine island in the world

The northern plain is divided into three sections, viz. the Punjab Plain, the Ganga Plain and the Brahmaputra Plain.

Punjab Plains: 

• The Western part of the Northern Plain is referred to as the Punjab Plains.
• Formed by the Indus and its tributaries, the larger part of this plain lies in Pakistan.
• The Indus and its tributaries-the Jhelum, the Chenab, the Ravi, the Beas and the Satluj originate in the Himalaya.
• This section of the plain is dominated by the doabs.

Do you know?

‘Doab’ is made up of two words — ‘do’ meaning two and ‘ab’ meaning water. Similarly ‘Punjab’, is also made up two words - ‘Punj’ meaning five and ‘ab’ meaning water

Ganga Plains: 

• The Ganga plain extends between Ghaggar and Teesta rivers.
• It is spread over the states of North India, Haryana, Delhi U.P. Bihar, partly Jharkhand and West Bengal to its East

Brahmaputra Plains: 

• This plain forms the eastern part of the northern plain and lies in Assam.
• In Assam lies the Brahmaputra plain and extends from West Bengal, through Assam and Bangladesh to India's eastern border.

Based on the relief features; the northern plain can be divided into four regions:

Bhabar: 

• After descending from the mountains, the rivers deposit pebbles in a narrow belt.
• The width of this belt is about 8 to 16 km and it lies parallel to the slopes of the Shiwaliks.
• This region is known as bhabar.
• All the streams disappear in this bhabar belt.

Terai: 

• South of this belt, the streams and rivers re-emerge and create a wet swampy and marshy region known as terai.
• This was a thickly forested region full of wildlife.
• The forests have been cleared to create agricultural land and to settle migrants from Pakistan after partition.
• Locate Dudhwa National Park in this region.

Bhangar: 

• The largest part of the northern plain is formed of older alluvium.
• They lie above the flood plains of the rivers and present a terrace like feature.
• This part is known as bhangar.
• The soil in this region contains calcareous deposits locally known as kankar.

Khadar: 

• The newer, younger deposits of the flood plains are called khadar.
• They are renewed almost every year and so are fertile, thus, ideal for intensive agriculture.

The Peninsular Plateau:

• The peninsular plateau is a tableland.
• It is composed of the oldest rocks (composed of the old crystalline, igneous and metamorphic rocks) because it was formed from the drifted part of the Gondwana land.
• Broad and shallow valleys and rounded hills are the characteristic features of this plateau.

The plateau can be broadly divided into two regions, viz. the Central Highlands and the Deccan Plateau.

The Central Highlands - The part of the peninsular plateau lying to the north of the Narmada River, covering a major area of the Malwa plateau, is known as the Central Highlands.

                                                                       Or

Malwa plateau and Chota Nagpur Plateau together are called Central Highlands.

• The Central Highlands lies to the north of the Narmada River.
• It covers the major portion of the Malwa plateau.
• The Vindhyan range is bounded by the Satpura range on the south and the Aravalis on the northwest.
• The further westward extension gradually merges with the sandy and rocky desert of Rajasthan.
• The flow of the rivers draining this region, namely the Chambal, the Sind, the Betwa and the Ken is from southwest to northeast, thus indicating the slope.
• It is wider in the west and narrower in the east.
• The rivers in this region flow from southwest to northeast; which indicates the slope of this region.
• Bundelkhand and Baghelkhand mark the eastward extension of this plateau.
• The plateau further extends eastwards into the Chhotanagpur plateau.
• The Chhotanagpur plateau marks the further eastward extension, drained by the Damodar river.

The Deccan Plateau:

• The Deccan Plateau lies to the south of the Narmada River.
• It is triangular in shape.
• The Satpura range flanks its broad base in the north.
• While the Mahadev, the Kaimur hills and the Maikal range form its easter extensions.
• The Deccan Plateau is higher in the west and slopes gently eastwards.
• An extension of the Plateau is also visible in the northeast-locally known as the Meghalaya, Karbi-Anglong Plateau and North Cachar Hills.
• It is separated by a fault from the Chotanagpur Plateau.
• Three prominent hill ranges from the west to east are the Garo, the Khasi and the Jaintia Hills.

The Western and the Eastern Ghats:

• The Western Ghats and the Eastern Ghats mark the western and the eastern edges of the Deccan Plateau.
• Western Ghats le parallel to the western coast.
• They are continuous and can be crossed through passes only.
• The Western Ghats are higher than the Eastern Ghats.
• Their average elevation is 900-1600 metres as against 600 metres of the Eastern Ghats.
• The Eastern Ghats stretch from the Mahanadi Valley to the Nigiris in the south.
• The Eastern Ghats are discontinuous and irregular and dissected by rivers draining into the Bay of Bengal.
• The Western Ghats cause orographic rain by facing the rain bearing moist winds to rise along the western slopes of the Ghats.
• The Western Ghats are known by different local names.
• The height of the Western Ghats progressively increases from north to south.
• The highest peaks include the Anai Mudi (2,695metres) and the Doda Betta (2,637 metres) Mahendragiri (1,501 metres) is the highest peak in the Eastern Ghats.
• Shevroy Hills and the Javadi Hills are located to the southeast of the Eastern Ghats.
• Locate the famous hill stations of Udagamandalam, popularly known as Ooty and the Kodaikanal.

Features of the peninsular plateau

• One of the distinct features of the peninsular plateau is the black soil area known as Deccan Trap.
• This is of volcanic origin hence the rocks are igneous.
• Actually these rocks have denuded over time and are responsible for the formation of black soil.
• The Araval Hills be on the western and north western margins of the peninsular plateau.
• These are highly eroded hills and are found as broken hills.

The Indian Desert:

• The Indian desert lies towards the western margins of the Aravali Hills.
• It is an undulating sandy plain covered with sand dunes.
• This region receives very low rainfall below 150 mm per year.
• It has arid climate with low vegetation cover.
• Streams appear during the rainy season.
• Soon after they disappear into the sand as they do not have enough water to reach the sea.
• Luni is the only large river in this region.
• Barchans (crescent shaped dunes) cover larger areas.
• But longitudinal dunes become more prominent near the Indo-Pakistan boundary.
• If you visit Jaisalmer, you may go to see a group of barchans.

The Coastal Plains:

• The Peninsular plateau is flanked by stretch of narrow coastal strips, running along the Arabian Sea on the west and the Bay of Bengal on the east.
• The western coast, sandwiched between the Western Ghats and the Arabian Sea, is a narrow plain.

Western Coastal Plain: - It consists of three sections:

1. The northern part of the coast is called the Konkan (Mumbai – Goa).
2. The central stretch is called the Kannad Plain.
3. While the southern stretch is referred to as the Malabar Coast.

Eastern Coastal Plain:

• The plains along the Bay of Bengal are wide and level.

• In the northern part, it is referred to as the Northern Circar.
• While the southern part is known as the Coromandel Coast.
• Large rivers, such as the Mahanadi, the Godavari, the Krishna and the Kaveri have formed extensive delta on this coast.
• Lake Chilika is an important feature along the eastern coast.

Do you know?

The Chilika Lake is the largest salt water lake in India. It lies in the state of Odisha, to the south of the Mahanadi delta.

The Islands:

Lakshadweep

• The Lakshadweep Islands group in the Arabian Sea is close to Kerala.
• This group of islands is composed of small coral islands.
• The Lakshadweep Islands were earlier known as Laccadive, Minicoy and Amindive.
• In 1973, these were named as Lakshadweep. It covers small area of 32 sq km.
• Kavaratti Island is the administrative headquarters of Lakshadweep.
• The island group has great diversity of flora and fauna.
• The Pitti Island, which is uninhabited, has a bird sanctuary.

Coral:

• Coral polyps are short-lived microscopic organisms, which live in colonies.
• They flourish in shallow, mud-free and warm waters.
• They secrete calcium carbonate.
• The coral secretion and their skeletons from coral deposits in the form of reefs.
• They are mainly of three kinds: barrier reef. fringing reef and atolls.
• The Great Barrier Reef of Australia is a good example of the first kind of coral reefs.
• Atolls are circular or horse shoe-shaped coral reefs.

Andaman and Nicobar

• The elongated chain of islands located in the Bay of Bengal extending from north to south are Andaman and Nicobar islands.
• They are bigger in size and are more numerous and scattered.
• The entire group of islands is divided into two broad categories.
• The Andaman in the north and the Nicobar in the south.
• It is believed that these islands are an elevated portion of submarine mountains.
• These island groups are of great strategic importance for the country.
• There is great diversity of flora and fauna in this group of islands too.
• These islands lie close to equator and experience equatorial climate and have thick forest cover.

Do you know?

India’s only active volcano is found on Barren island in Andaman and Nicobar group of Islands.

Influence of physical features:

• Each region complements the other and makes the country richer in its natural resources.
• The mountains are the major sources of water and forest wealth.
• The northern plains are the granaries of the country.
• They provide the base for early civilisations.
• The plateau is a storehouse of minerals which has played a crucial role in the industrialization of the country.
• The coastal region and island groups provide sites for fishing and port activities.
• Thus, the diverse physical features of the land have immense future possibilities of development