Indian subcontinent
According to NCERT, Indian subcontinent – Pakistan, Nepal, Bhutan, India and Bangladesh
Generally, includes the countries of Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, and Sri Lanka. Sometimes, the British Indian Ocean Territory is also included.
The terms Indian subcontinent and South Asia are often used interchangeably to denote the region, although the geopolitical term of South Asia frequently includes Afghanistan. The United Nations geosphere for Asia also includes Iran in Southern Asia.
Geographically, it is the peninsular region in South-Central Asia, delineated by the Himalayas in the north, the Hindu Kush in the west, and the Arakanese in the east.
Indian Geological regions
The Peninsular block
Himalayas and other Peninsular mountains
Indo Ganga Brahmaputra Plain
Physiography
The Northern and North-eastern Mountains
The Northern Plain
The Peninsular Plateau
The Indian Desert
The Coastal Plains
The Islands
The Northern and North Eastern Mountains
2500 km in length and 160 (Arunachal Pradesh) to 400 km (Kashmir) in width
Altitudinal variations are greater in the eastern half than those in the western half
Weak and flexible sedimentary rocks
Regional divisions
Punjab Himalayas – between Indus and Sutlej – also known as Kashmir and Himachal Himalayas
Kumaon Himalayas – Sutlej and Kali
Nepal Himalayas – Kali and Teesta
Important peaks are the Mt. Everest, Kanchenjunga, Makalu, Dhaula Giri, Annapurna, Manaslu, and Gosainath
Assam Himalayas – Teesta and Dihang
Trans Himalayas
Tertiary granite, Tethys sediments are raised as trans Himalayan ranges – has marine fossils
Karakoram, Ladakh, Zaskar and Kailash on the east in Tibet
Karakoram
It is known for its glaciers – Hispar, Biafo, Baltora, Siachen glacier
K2 or Godwin Austin – highest peak
Ladakh
Stok Kangri – highest peak
Kailash range
- Eastern continuation of Ladakh range in Tibet
- Man Sarovar and Rakshastal are near Kailash range
- Indus, Sutlej and Brahmaputra originate her
- Mt. Kailash – highest peak
Zaskar
Greater or Inner Himalayas or Himadri
Most continuous of the loftiest peaks (6000 m)
2400 km in length
Folds are asymmetrical
Southern slope is steep and northern slope is gentle – hog back shaped mountain
Core part is composed of granite
Important glaciers – Gangotri (Bhagirathi) and Satopanth (Alaknanda)
Important passes – Shipkila pass in Himachal Pradesh between India and China – Sutlej enters
Himachal or Lesser Himalayas or Middle Himalayas or Lower Himalayas or Inner Himalayas
From the Indus River in Pakistan across northern India, Nepal and Bhutan but then the two ranges become increasingly difficult to differentiate east of Bhutan as the ranges approach the Brahmaputra River.
Most rugged mountain system
Highly compressed and altered rocks
Altitude – 3700 to 4500 m
Average width – 50 km
- Pir Panjal – J&K - Longest
- Dauladhar – Himachal Pradesh
- Nag Tiba - Uttarakhand
- Mussorie – Uttarakhand (Kumaon)
- Mahabharat – Nepal
Has Kashmir Valley, Kangra and Kullu valley in HP
Well known for hill stations – Mussoorie, Nainital, Ranikhet, Shimla, Darjeeling
Significant for high rock erosion
Outer Himalayas or Shiwaliks or Churia Hills
Width – 10 to 50 km
Altitude – 900 to 1100 m
From the Indus River to the Brahmaputra River; Between the Teesta and Raidāk Rivers in Assam is a gap (absent) of about 90 km
Shivaliks is known as Pothothar (Potwar) Plateau in Pakistan where Islamabad is located
- Delhi ridge is mentioned as Potwar plateau in NCERT
Made up of sand stone, conglomerate, limestones – most of the Shivaliks is formed from the eroded debris from lesser Himalayas – rest due to crustal bending
Composed of unconsolidated sediments brought down by rivers from main Himalayan ranges
Valleys are covered with thick gravel and alluvium
The longitudinal valley lying between lesser Himalaya and Shivaliks are known as Duns
- Duns are alluvium deposited by mountain streams – to form a plain like region
- Dehra, Kotli, Patli, Jammu Dun, Pathankot Dun, Kathmandu
- Dehra Dun is the largest of all dun
- Jammu Dun and Kathmandu Dun are found in Kashmir Himalayas
Kashmir or North-western Himalayas
Karakoram, Ladakh, Zaskar, Greater Himalayas, Pir Panjal ranges
- The Outer Himalayas of this Kashmir region area called Jammu hills
The northeastern part of the Kashmir Himalayas is a cold desert, which lies between the Greater Himalayas and the Karakoram ranges.
Ladakh cold desert is bound by Karakoram and Zanskar
Kashmir Valley and Dal Lake in Srinagar – Intermontane valley between the Great Himalayas and the Pir Panjal range. (Lesser Himalayas)
- Kashmir valley is drained by Jhelum river.
- Jhelum is still in its youth stage and yet forms meanders – a typical feature associated with the mature stage in the evolution of fluvial land form
- Reason - due to the flat terrain of the Kashmir valley
- Dal Lake is considered to be a cut of portion of Jhelum river
- Srinagar is located on the banks of Jhelum river.
The Kashmir Himalayas are also famous for Karewa formations, which are useful for the cultivation of Zafran, a local variety of saffron, apple and other dry fruit cultivation.
Karewas are the thick deposits of glacial clay and other materials embedded with moraines.
Passes of the region
- Zoji La on the Great Himalayas
- Banihal pass on the Pir Panjal,
- Photu La on the Zaskar and
- Khardung La on the Ladakh range.
Important fresh lakes - Dal and Wular and salt water lakes - Pangong Tso, Tso Kar and Tso Moriri.
Drained by the river Indus, Jhelum and Chenab.
Pilgrimage - Vaishno Devi, Amarnath Cave, Charar-e-Sharif,
The southernmost part of this region consists of longitudinal valleys known as ‘duns’ - Jammu dun and Pathankot dun.
Himachal and Uttarakhand Himalayas
Between Ravi and Kali
- Drained by Ganga and Indus river systems
- Tributaries of the Indus include the river Ravi, the Beas and the Satluj, and the tributaries of Ganga flowing through this region include the Yamuna and the Ghaghara
Kumaon Himalayas – Named after the Kumaon tribes
All three sections of Himalayas are present and very much prominent in Kumaon Himalayas
- Great Himalayan range, the Lesser Himalayas (which is locally known as Dhaoladhar in Himachal Pradesh and Nagtibha in Uttarakhand) and the Shiwalik range from the North to the South.
Lesser Himalayas attracted the British administration – hill stations as Dharamshala, Mussoorie, Shimla, Kaosani and the cantonment towns and health resorts such as Shimla, Nainital, Mussoorie, Kasauli, Almora, Lansdowne and Ranikhet, Bageshwar etc. were developed in this region.
- HP – Dharmashala, Shimla, Kasauli
- Uttarakhand – Mussorie, Kaosani, Lansdowne, Almora, Ranikhet, Bageshwar
The two distinguishing features of this region are the ‘Shiwalik’ and ‘Dun formations’.
- The word shiwalik has its origin in the geological formation found in and around a place called Sivawala near Dehra Dun which was once a headquarter of the Imperial Survey and which subsequently established its permanent headquarters at Dehra Dun.
The Northern part of Himachal Himalayas is cold desert – Lahaul and Spiti
Important duns
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.
In the Great Himalayan range, the valleys are mostly inhabited by the Bhotias. These are nomadic groups who migrate to ‘Bugyals’ (the summer glasslands in the higher reaches) during summer months and return to the valleys during winters.
The famous ‘Valley of flowers’ NP is also situated in this region.
The places of pilgrimage such as the Gangotri, Yamunotri, Kedarnath, Badrinath and Hemkund Sahib (Uttarakhand) are also situated in this part.
The region is also known to have five famous Prayags (river confluences).
Pindari (source of pindar river which meets Alaknanda at Karnaprayag), Gangotri, and Milam (Source of Goriganga) are important glaciers in this division.
Darjeeling and Sikkim Himalayas:
Between Nepal Himalayas and Bhutan Himalayas
The higher reaches of this region are inhabited by Lepcha tribes while the southern part, particularly the Darjiling Himalayas, has a mixed population of Nepalis, Bengalis and tribals from Central India.
As compared to the other sections of the Himalayas, these along with the Arunachal Himalayas are conspicuous by the absence of the Shiwalik formations.
- In place of the Shiwaliks here, the ‘duar formations’ are important, which have also been used for the development of tea gardens.
- Duars – alluvial plains on foothills of Lesser Himalayas due to the absence of Shivaliks – Present in northeastern Himalayas and not in north western Himalays
Drained by Teesta river from Zemu Glacier of Khanchenjunga
Sikkim and Darjiling Himalayas are also known for various types of orchids – rich in flora and fauna
Arunachal Himalayas
From Bhutan Himalayas to Diphu pass – Between Teesta and Brahmaputra
- Namcha Barva in Greater Himalayas is the easternmost point of Arunachal Pradesh
Southwest to northeast orientation
Outer Himalayas are divided into small hills by the rivers dissecting them – Dafla, Miri, Abhor and Mishmi – named after the tribes
Peaks – Kangto in AP and Namcha Barwa in Tibet
- Kangto peak is the highest point in Arunachal Pradesh
- Kangto glacier is the source of a tributary of Kameng river
- It is a virgin peak – meaning unclimbed mountain
Hydroelectrical potential is high
Jhum cultivation
Tribals from west to east - Monpa, Abor, Mishmi, Nyishi and the Nagas.
Eastern hills or Purvanchal
North to South
Has strong sandstones (sedimentary rocks)
Patkai Bum, Naga Hills, Manipur Hills, Mizo or Lushai hills
These are low hills – jhum cultivation
The Purvanchal is joined by Meghalaya Plateau in the west and its extension of the Myanmar mountain chain continues to Andaman and Nicobar Islands and the Archipelago of Indonesia.
Loktak lake of Manipur is surrounded by hills on all sides
Mizoram - known as the ‘Molassis basin’ which is made up of soft unconsolidated deposits.
The rivers in the eastern part of Manipur are the tributaries of Chindwin, which in turn is a tributary of the Irrawady of Myanmar.
Northern Plains
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.
- When the Indian plate collided with the Eurasian plate The anticline fold formed was Himalayas
- The synclinal depression was deposited with the sediments or alluvium by the Himalayan rivers giving rise to the Northern plains
7 lakh sq km
3200 km from east to west; Average width – 150 to 300 km
Maximum depth – 1000 to 2000 m – depth of the deposit decreases from west to east
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.
Bhabar
Narrow belt (8-10 km) parallel to the Shiwalik foothills at the break-up of the slope – from Indus to Tista
Merger of alluvial fans
Streams and rivers coming from the mountains, deposit heavy materials (Coarse deposits) of rocks and boulders, and at times, disappear in this zone.
The porosity of this plain is high
It is wider in the western plains than in the east
This plane is not suitable for cultivation, only big trees with large roots thrive in this region
Terai (northern fringes of Uttarakhand, UP and Bihar)
South of Bhabar (10 to 20 km)
Most of the streams and rivers re-emerge without having any properly demarcated channel, thereby, creating marshy and swampy conditions known as the Terai.
- Those rivers remerge and join to form large rivers
- Terai region will have shallow waters above the surface
This has a luxurious growth of natural vegetation (thick forested region) and houses a varied wild life (biodiversity rich) - zone of excessive dampness thick forest and rich wildlife.
Terai region is more prominent in the east due to higher rainfall
The Tarai is wider in the eastern parts of the great Plains, especially in Brahmaputra valley due to heavy rainfall. In many states, the tarai forest have been cleared for cultivation.
This part of the northern plains have national parks and wildlife sanctuaries
North east India has pristine terai region. Whereas in UP and Bihar, the terai has been reclaimed for agriculture mostly – sugarcane, rice and wheat
Terai soils are nitrogen rich and have humus content
Terai Arc Landscape (TAL)
- Stretch from Yamuna and Bhagmati spanning India and Nepal
- Spread across Uttarakhand, UP and Bihar and low lying hills of Nepal
Alluvial plains
Bhangar - Old alluvial deposits
- Largest part of the northern plain
- Above the floods plains and presents a terrace like feature
- Soil – Dark, humus rich and productive
- Has calcareous deposits known as kankar or calcium carbonate nodules
- Less fertile than Khadar due to older alluvium
- Contains fossils of various animals and humans like rhinoceros, hippopotamus, elephants
- Variations – includes Barind plains in Bengal and Bhur Formations in Ganga Yamuna Doab
Khadar – new alluvial deposits
- Renewed almost every year – floodplains adjacent to the rivers – fertile and ideal for intensive agriculture
The states of Haryana and Delhi form a water divide between the Indus and the Ganga river systems.
Divisions
- Rajasthan Plain
- Western aspect is Marusthali; eastern aspect is semi arid called Bagar plains
- North Eastern aspect of Rajasthan is Ghaggar plains – alluvial tract left by Saraswati
- South western aspect of Rajsthan is Rohi Plains - fertile
- Punjab Haryana plains – formed by Indus and its tributaries – larger part of this plain lies in Pakistan – dominated by doabs (two water) – Punjab (5 water)
- Three rivers splits the Panjab plains in India (Ravi, Beas and Sutlej)
- Bari doab between Ravi and Beas
- Bist doab between Beas and Sutlej
- Malwa Plain – south of Sutlej
- Southern and south western aspect of Punjab plain is Haryana Bhiwani Bagar plain
Important features
- • Dhayas – small streams will have raised banks due to deposition
- • Bet – new alluvium is locally known as Bet or Bet lands – otherwise known as Khadar
- Ganga plain – between Ghaggar and Teesta river – Haryana, Delhi, UP, Bihar, partly Jharkhand and West Bengal
- Upper Ganga plain – Ganga Yamuna doab
- Bhurs – fine sand deposits by wind – due to its proximity with Thar desert
- Middle Ganga plain
- Most of the Eastern UP and Bihar till Patna
- Rivers meanders, oz bow lakes
- Lower Ganga plain
- Bounded by Chotanagpur plateau, Patna, Assam and Bangladesh
- Largely monotonous without much of undulations and other land features
- South Western aspect of lower Ganga plain (east of Chotanagpur plateau) is known as Rahr plain – drained by Damodar and Subarnarekha river
- South eastern aspect of lower Ganga plain is Sudarbans delta
- Brahmaputra plain or Assam valley
- Upper Assam Valley and Lower Assam Valley by 94 degree E Longitude
- Upper – largely monotonous
- Lower – interspersed by hills of Meghalaya plateau
- Brahmaputra river – braiding pattern
Peninsular Plateau
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.
- Karbi Anglong and Meghalaya Plateau in the northeast and Jaisalmer in the west where it has been covered by the longitudinal sand ridges and barchans are also extensions of this block
The Peninsular India is made up of a series of patland plateaus such as the Hazaribagh plateau, the Palamu plateau, the Ranchi plateau, the Malwa plateau, the Coimbatore plateau and Karnataka Plateau
- Patland plateau or Pat is the local name for lava- capped Mesas
General elevation of the plateau decreases from the west to east (north west to south east)
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.
- A tor or castle koppie or kopje, is a large, free-standing rock outcrop that rises abruptly from the surrounding smooth and gentle slopes of a rounded hill summit or ridge crest.
The northwestern part of the plateau has a complex relief of gullies, ravines and gorges. The ravines of Chambal, Bhind and Morena are some of the well-known examples. (All in MP)
Bhima fault - transverse fault located in the Southern part of the Bhima basin in Maharashtra
The rift valleys of the Narmada, the Tapi and the Damodar and the Satpura block mountains are examples of faulting
Deccan plateau has mostly igneous rocks and the Central Highlands has mostly metamorphic rocks
Central Indian Tectonic Zone
Because of this India has three rift valleys
- Sonata rift valley
- So – Son, Na – Narmada, Ta – Tapi
- Cambay rift valley in Gujarat
- Kutch rift valley in Gujarat
Four rivers of India flow in rift valley – Narmada, Tapi, Son and Damodar
Deccan Plateau
This is bordered by the Western Ghats in the west, Eastern Ghats in the east and the Satpura in the north – south of river Narmada
- Mahadeo, Kaimur hills and Maikal range are its eastward expansions
Black soil – Western and northwestern part of the Deccan plateau
Western Ghats
- Formed due to faulting only – can be considered as block mountain also – they are also escarpments
- They are faulted, eroded and submerged western end of Deccan plateau
- From South of Tapi to Southern tip of India (Agasthiya Malai is the southern most)
- 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.
- Tapi valley and Satmala Hills (Nasik, Maharashtra) form the northern most tip of Western Ghats
- Their average elevation is about 1,500 m with the height increasing from north to south.
- ‘Anaimudi’ (2,695 m) in Kerala, the highest peak of Peninsular plateau is located on the Anaimalai hills of the Western Ghats followed by Dodabetta (2,637 m) in TN on the Nilgiri hills.
- Highest peaks in Maharashtra – Kalsubai (1), Salher (2), Dhodap hill (3)
- Passes in Western Ghats (north to south)
- Thal Ghat or Kasara Ghat – between Mumbai and Nasik (passes through Nasik)
- Bhor ghat – Between Mumbai and Pune
- Chorla Ghat - intersection of the borders of the states of Goa, Karnataka,[1] and Maharashtra
- Pal Ghat in Kerala
- Shenkota in TN – southern most
- Ooty in Nilgiri Hills (Queen of Hill Stations) and Sigur Plateau in Nilgiris
- Kodaikanal (Princess of hill stations) in upper Palani Hills which is eastward expansion of Western Ghats
- Western Ghats are the typical example of escarpment. The characteristics of escarpment are
- Runs parallel to the coast
- Runs for hundreds or thousands of km
- Steep slope for atleast 1 km height
- Show remarkable continuity and linearity despite structural variations
- Display erosional and youthful characteristics
- Tall waterfalls on the side of Arabian sea coast
- Jog falls – highest waterfall – Sharavati river in Karnataka
- Eastern Ghats
- Residual hills – eroded Deccan plateau
- Eastern Ghats are neither continuous nor have same composition
- Comprising the discontinuous and low hills are highly eroded by the rivers such as the Mahanadi, the Godavari, the Krishna, the Kaveri, etc
- They stretch from Mahanadi valley to Nilgiris
- Mahendragiri (1501 m) in Odisha is the highest peak
- But presently Jindhagada is considered to be the highest peak – Andhra
- Divisions
- Eastern Hills – Northern Circar – part in Odisha
- Cuddapah ranges in AP
- TN Hills
North to South
- Nallamala, Venukonda, Palkonda, Nagari, Seshachalam in AP
- Javadi, Shevaroy, Punchamalai, Sirumalai in TN
- Sirumalai is the last mountain range of Eastern Ghats
- South of Sirumalai
- Palani Hills – eastward extension of Western Ghats
- Varushnad hills – south of Palani
- Eastern Ghats are older than Western Ghats
- Biligiriranga Hills form an ecological corridor between Eastern and Western Ghats
North Deccan
- Maharashtra plateau – Deccan traps – basaltic – black soil
- Mahanadi basin
- Chhattisgarh plain – Dhalli Rajahara hills (iron ore) and Korba coal field – Bhilai steel plant
- Odisha uplands – Garjat hills (coal)
- Dandakaranya plateau – tri junction of Chhattisgarh, Odisha and AP
- Bailadila (iron) in Abujhmar hills
South Deccan
- Karnataka plateau
- Malnad – western portion – hilly terrain
- Maidan – eastern portion – relatively plain
- Telangana plateau
- TN uplands
- Charnockites mineral in Javadi and Shevaroy hills – metamorphic rocks used as gem stones and pottery – non metallic mineral
Central Highlands
The part of Peninsula plateau lying north of the Narmada river covering a major area of the Malwa plateau is known as the Central Highlands
An eastern extension of the Central Highland is formed by the Rajmahal hills.
Central Highlands are wider in the west and narrower in the east.
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.
North Central Highland
- Aravalli range
- North Western aspect of Aravalli range is Jarga hills
- Goranghat pass – between Guru Shikar and Mt. Abu
- Malwa plateau – between Vindhyas and Arabian Sea
- Drained by two system of rivers
- Mahi and Sabarmati
- Tributaries of Chambal
South Central Highland
- Vindhayas, Satpuras, Bundelkhand plateau, Baghelkhand
- Vindhyan
- From Jobat in Gujarat to Sasaram in Bihar – 1200 km in length
- Block mountains caused due to normal faulting
- Slope is steep on south and gentle on north aspect – escarpment
- General elevation – 300 to 600 m
- Eastern aspect is continued as Bharner and Kaimur range
- Satpura
- 7 hills – but 3 are important – Rajpipla Hills, Mahadeo Hills and Maikala hills – 900 km in length
- Block mountains caused due to normal faulting
- General elevation – 900 to 1000 m
- Dhupgarh – highest peak in the range
- Amarkantak plateau – meeting point of Vindhya and Satpura - Narmada, Mahanadi and Son
- The Satpura range is formed by a series of scarped plateaus on the south.
- The general elevation of the Central Highlands ranges between 700-1,000 m and it slopes towards the north and northeastern directions. (from southwest to northeast)
- This slope is visible from the tributaries of Yamuna
- Most of the tributaries of the river Yamuna have their origin in the Vindhyan and Kaimur ranges.
- Banas is the only significant tributary of the river Chambal that originates from the Aravalli in the west.
North-eastern Plateau:
In fact it is an extension of the main Peninsular plateau. It is believed that due to the force exerted by the northeastward movement of the Indian plate at the time of the Himalayan origin, a huge fault was created between the Rajmahal hills and the Meghalaya plateau – Malda fault or malda gap
- Malda is occupied by the Ganga river and filled by sediments now – Bangladesh
- Rocks in Meghalaya plateau and Chotanagpur plateau are similar – archean granites
- Meghalaya is also rich in iron, coal and other metallic minerals similar to Chotanagpur plateau
Later, this depression got filled up by the deposition activity of the numerous rivers.
Today, the Meghalaya and Karbi Anglong plateau (North Cachar Hills and Mikir Hills) stand detached from the main Peninsular Block.
The Meghalaya plateau is further sub-divided into three: (i) The Garo Hills; (ii) The Khasi Hills; (iii) The Jaintia Hills, named after the tribal groups inhabiting this region.
- Shillong peak is the highest peak in Megahalaya
An extension of this is also seen in the Karbi Anglong plateau (Mikir hills and North Cachar Hills) of Assam.
Similar to the Chotanagpur plateau, the Meghalaya plateau is also rich in mineral resources like coal, iron ore, sillimanite, limestone and uranium.
This area receives maximum rainfall from the south west monsoon.
- As a result, the Meghalaya plateau has a highly eroded surface. Cherrapunji displays a bare rocky surface devoid of any permanent vegetation cover.
Indian Desert
• Northwest of Aravali hills – great Indian desert - Also called Marusthali
• Less than 15 cm per year
• During Mesozoic era – region was under the sea
This can be corroborated by the evidence available at wood fossils park at Aakal and marine deposits around Brahmsar, near Jaisalmer (The approximate age of the woodfossils is estimated to be 180 million years).
• Though the underlying rock structure of the desert is an extension of the Peninsular plateau, yet, due to extreme arid conditions, its surface features have been carved by physical weathering and wind actions.
• Barchans cover larger areas but longitudinal dunes become prominent near the Indo Pakistan border
• On the basis of the orientation, the desert can be divided into two parts: the northern part is sloping towards Sindh and the southern towards the Rann of Kachchh.
• Oasis is found in the southern part
• Most of the rivers in this region are ephemeral. Luni river flowing in the southern part of the desert is of some significance.
• The lakes and the playas have brackish water which is the main source of obtaining salt.
Coastal Plains
• Western coastal plains
Submerged coastal plain and narrow
- Arabian sea side is faulted and has steep slope
- Erosion is more
City of Dwaraka which was once a part of the Indian mainland situated along the west coast is submerged under water.
- Because of this submergence it is a narrow belt and provides natural conditions for the development of ports and harbours.
- Divisions
- the Kachchh and Kathiawar coast in Gujarat,
- Konkan coast in Maharashtra and Goa,
- Kannad coast in Karnataka and
- Malabar Coast in Kerala
- Western coastal plains are narrow in the middle and get broader towards north and south.
- 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.
- Backwaters - a part of a river not reached by the current, where the water is stagnant.
- Every year the famous Nehru Trophy Vallamkali (boat race) is held in Punnamada Kayal (Vembanad lake) in Kerala.
- Eastern Coastal plain
- Broader and emergent coast – coastal plains are added – deposition is prominent
- Even Malabar coast is coast of emergence
- Continental shelf extends up to 500 km into the sea which makes it difficult for the development of good ports and harbours.
- Divisions
- North – Northern Circar
- Odisha coast is called Utkal coast
- South – Coromandel Coast
- Casuarina is largely found along the coromandel coast
Deltas and estuaries
• Steep slope and gradual slope
• Short course and long course
• Rift valley rivers do not form delta
Bottom of rift valleys are hard rocks and resist erosion
• Submergent coast and emergent coast
Western Coast and Eastern Coast
Western Coast
Continental slope is steeper and Continental shelf is very narrow
Continental slope is very steep dur to subsidence of Arabian sea floor.
Submergent coast
Eastern Coast
Continental shelf is wider – due to river deposits (peninsular India is tilted towards east – reason for many east flowing rivers)
Artificial harbours are created by dredging the shelf. Chennai is one of the oldest artificial harbour.
Emergent coast
West flowing rivers form only estuaries
- It flows only for a shorter length and erodes only less sediments
- Narmada and Tapi flows in a rift valley and it doesn’t carry huge sediments.
- Continental slope is steeper and shelf is narrow, the river deposits get sedimented into the sea and cannot form delta
- East flowing rivers form deltas
- Continental shelf is wider and rivers bring large amount of sediments
- Brazilian current takes away the deposits of Amazon river. Thus Amazon does not forms delta
ISLANDS
Andaman and Nicobar Islands (572 Islands – 30 are inhabited)
• These islands receive convectional rainfall and have an equatorial type of vegetation.
• Some of the islands are fringed with coral reefs.
• Saltwater crocodiles are also found in abundance.
• The State Animal of Andaman and Nicobar Islands – dugong
• The islands host the Andaman and Nicobar Command, the only tri-service geographical command of the Indian Armed Forces.
• Some important mountain peaks in Andaman and Nicobar islands
Saddle peak (North Andaman – 738 m) – highest peak in Andaman and Nicobar Islands
Mount Thullier (Great Nicobar – 642 m) – highest point in Nicobar Islands
Mount Diavolo (Middle Andaman – 515 m),
Mount Koyob (South Andaman – 460 m)
Important channels
Coco Channel - North Andaman of Great Andaman and Coco Islands of Myanmar
- Three Coco Islands and Preparis Island in the archipelago's north belong to Myanmar.
- Cocos Islands belong to Australia
Duncan Passage – Rutland Island of Great Andaman and Little Andaman
10 degree channel – Little Andaman of Andaman Islands and Car Nicobar of Nicobar Islands
St George’s Channel – Little Nicobar and Great Nicobar
Great Channel of 6 degree channel - Indira Point of Great Nicobar and Sabang island of Aceh province of Sumatra island of Indonesia
Andaman Islands
The Andaman islands consist of four groups:
- Great Andaman
- East Volcano Islands (Narcondam in north and Barren Island in south)
- Ritchie's Archipelago
- Little Andaman
Great Andaman is the main archipelago of the Andaman Islands of India. It comprises seven major islands.
- From north to south, these are North Andaman, Interview Island, Middle Andaman, Long Island, Baratang Island, South Andaman, and Rutland Island.
Port Blair, the capital of Andaman Nicobar Islands lies in the South Andaman.
The North and South Sentinel Islands – present on west side of Andaman Islands
- belong to South Andaman and are between the South Andaman and Duncan Passage
Ritchie's Archipelago between and east of Middle Andaman and South Andaman.
- 2018 - Ross Island was renamed as Netaji Subhash Chandra Bose Island; Neil Island as Shaheed Island; and Havelock Island as Swaraj Island.
Narcondam Island (east of North Andaman) – dormant volcano
Barren Island – east of Middle Andaman - only active volcano in South Asia last erupted in 2017.
Baratang Island (between Middle and South Andaman) – has mud volcanoes - erupted sporadically, with recent eruptions in 2005.
Mahatma Gandhi National Park in South Andaman which are on two island groups - Labyrinth Islands and Twin Islands.
Nicobar Islands
Important Islands from North to South – Car Nicobar (Northernmost), Little Nicobar and Great Nicobar (Southernmost)
Great Nicobar is the largest island among Nicobar Islands
Indira Point - 6o 47’ N – Southernmost point of India – in Great Nicobar (formerly known as Pygmalion Point)
UNESCO has declared the Great Nicobar Island as one of the World Network of Biosphere Reserves.
Lakshadweep Islands
Lakshadweep means "one lakh islands" in Sanskrit
Malayalam most spoken language in the territory.
There are around 36 islands of which 11 are inhabited.
1973 – renamed as Lakshadweep
These islands are located at a distance of 280 km-480 km off the Kerala coast.
The entire island group is built of coral deposits.
Most of the islands have low elevation and do not rise more than five metre above sea level (Extremely Vulnerable to sea level change).
The islands form the smallest Union Territory of India by both area and population . It is a uni-district UT.
The islands are grouped North to South as follows:
- Amindivi Islands (Amini, Keltan, Chetlat, Kadmat, Bitra, Perumal Par).
- Laccadive Islands or Cannanore Islands (Andrott, Agatti, Kalpeni, Kavaratti, Pitti, Bangaram Atoll, Suheli Par)
- Minicoy Island – southernmost island
Channels of Lakshadweep
- 11 degree channel – Amindivi islands and Laccadive islands
- 9 degree channel or Mamala channel – Laccadive islands and Minicoy island
- 8 degree channel – Minicoy island of Lakshadweep and Maldives
- Andrott Island of Laccadive Islands – largest island by area
- Minicoy island – second largest island and most advanced island
- The Pitti Island of Laccadive Islands which is uninhabited, has a bird sanctuary.
- The entry to Lakshadweep islands is restricted. One requires an entry permit issued by Lakshadweep Administration to visit these islands.