Checkout handpicked notes of NCERT class 9 Geography chapter 2 notes (The Physical Features of India) by Vibha Madam, and don’t forget to share your valuable comments in the comment below to motivate our author.
Physical features of India
Factors which influence the formation of land
- Geographical activities
Due to the internal heat of the earth the current of semi molten rocks move towards The crust, and tear it apart, dividing it into large fragments which are called tectonic plates.
Three Types of plate movements
- Convergent- Movement of plates toward each other
- Divergent- Two plates moves away from each other
- Transforms- two plates move horizontally passing each other
Theory of plate tectonics
According to this theory, The crust of the earth has been formed out of seven major and minor plates. The stress of the plates results in the building of stresses within the plate and the continual rock above, leading to folding and faulting and volcanic activities.
The seven major tectonic plates
- The Pacific
- The North American
- The south American
- The Eurasian
- The African
- The Indo-Australian
- The Antarctic places
When rock strata are subjected to compressional forces, they are often deformed by being in a process called holding.
When the rocks are subjected to tensional forces, they are stretched in the opposite direction. Due to this stretching the Rocks get fractured. Such fracturing of the rock is called faulting.
Formation of the Himalayas
- The Indo-Australian plate collided with the much larger Eurasian plate.
- The northern edge of the Indo-Australian was posed Beneath The Eurasian plate.
- Under the impact of this collision, the sedimentary rocks of the enclosed Ocean were folded to form the mountain system.
Formation of plains
- To the south of the Himalayas, a basin or depression was formed.
- The North Indian plain was born between the Himalayas and the peninsular plateau.
Formation of Peninsular plateau and the Arabian Sea
When the Himalayas were being formed, two major events affected the plateau. First the enormous volcanic outbreak in the North Western part of plateau. The second Arabian Sea was formed due to the subsidence of this land mass.
Relief and physical division of India
- The Himalayan mountains
- The northern plains
- The peninsular plateau
- The coastal plains
- The great Indian desert
- The Islands
The Himalayan mountains
- From Kashmir to Assam
- About 2400 km long and 150- 450 km wide
- Stretch from the Indus river (W) to the Brahmaputra river (E)
- The Altitude is Greater in Eastern half
Three parallel ranges
- The Himadri
- The Himachal
- The Shiwaliks
- Elevation – more than 6000 metre
- Important peak – Mount Everest (8848m) Nepal Kanchenjunga 3598m Sikkim
- Glaciers- Gangotri Yamunotri
- Elevation- 3700 m to 4500 mm width 50 kilometre
- Important Hill- Dalhousie Dharamshala Shimla
- Range- Pir Panjal, Dhaula Dhar
- Altitude – between 900m – 1100m
- Width- 10 – 50 km
- Duns – Dehradun, Patlidun
Division of Himalaya on the basis of regions
Western Himalayas- Punjab Himalaya between Indus and Satluj river
The central Himalaya- Kumaon between Satluj and Kali river
The Eastern Himalayas – between Kali and Tista river [ Nepal]
The Assam Hills – between Tista and river Dihang (Purvanchal) imp hills ;- patkai, Naga, Manipur, Mizo hills
The Eastern Himalayas – Purvanchal beyond Dihang gorge
Ques– Why are the Himalayas called young fold mountains?
Ans– The Himalayas are not very old, they are of recent birth.
Ques– In which state Garo, Khasi, Jaintia hills are located?
The Northern plains
Stretching about 2400 kilometre long and 240to 320 km broad from west to east. This plane has been formed by the interplay of the three major rivers i.e., the Indus, the Ganga, the Brahmaputra. This vast plains can be divided into two:
The Indus River Basin
It is known as the Punjab Plains. This region is drained by the Indus and its tributaries i.e., Jhelum Chenab Beas Ravi and Sutlej.
The Ganga Brahmaputra Basin
Ganga enters the (UP) Haridwar Brahmaputra enters Arunachal Pradesh. It is joined in Bangladesh (Meghna).
The Ganga plain extends between Ghaghra and Teesta river. it is spread over the states of North India, Haryana, Delhi, UP, Bihar, Jharkhand and West Bengal to its East.
Plains are divided into:
Bhabar- Stretch of this belt about 8 to 16 kilometre in width. It is a narrow belt covered with pebbles lying from Indus to Tista.
Tarai- it is wet and marshy. It has thick forest .
Bhangar- It is composed of old alluvium. It is less fertile as compared to the khadar.
Khadar- It is composed of new alluvium. It is very fertile.
Importance of Northern Plains:
- These plains are the granaries of India.
- These plains are of great economic and social significance.
- The plains have a good network of roads and railways.
- This region has sufficient employment opportunities.
- This plain is a site of the ancient civilizations of Mohenjo-Daro and Harappa.
The Peninsular Plateau:
It was formed due to the breaking and drifting of the Gondwana land and thus making it a part of the oldest landmass. This plateau consists of two broad divisions:
The Central highland:
- It is linked to the north of the Narmada river.
- It is known as the Malwa plateau.
- It is bounded by the Aravalli range in West and the Vindhya range in south.
- Malwa plateau extends upto the Chhota Nagpur Plateau.
- Important river- Chambal, Sind, Son, Damodar.
- Local name of Chota Nagpur is Bundelkhand and Baghelkhand.
The Deccan Plateau:
- Extension of the plateau is visible in the North East
- Three prominent Hills Garo, Khasi, Jaintia.
- The Western Ghats and Eastern Ghats at two ages of DP.
a) Western Ghats:
- The Western Ghats are higher than the Eastern Ghats.
- Average elevation 900 to 1600 metre.
- These Ghats receive orographic rainfall.
- The height of this Ghat increases from north to south.
- Highest peak- The Anai Mudi 2695 metre and the Doda Betta 2637 metre
b) Eastern Ghats:
- It stretched from the Mahanadi Valley to Nilgiris.
- Average elevation 600m.
- These Ghats are discontinuous and irregular.
- Highest peak- Mahendra Giri 1501m.
The Coastal plains
a) The Western coast:
- It consists of 3 sections- Kannada, Konkan, Malabar.
- Northern part of the cost is called konkan( Maharashtra and Karnataka)
- The Southern part is called Malabar Coast.
- Important river- Narmada, Tapi, Mahi.
- Natural harbours- Mumbai, Marmagao.
b) The Eastern coast:
- Extend from SubarnaRekha river (north) to Kanyakumari (South) 1100km
- It is broader than Western Plains.
- Rivers -mahanadi, Godavari, Krishna, Kaveri.
- Southern Part- Coromandel Coast
Delta- Ganga-Brahmaputra Delta
Lake- Chilika (Odisha)
The Great Indian Desert
- Extends in Rajasthan upto Sind in Pakistan.
- Only river- Luni
- It lies to the west of the Aravalli range
- The region receives very low rainfall and is covered with sand.
The Island groups
Main Island- Lakshadweep, Andaman and Nicobar.
Lakshadweep (Coral Island):
- Located in the Arabian Sea
- 36 groups of island
- Former names of Lakshadweep i.es., Laccadive, Minicoy, Amindivik.
- Renamed Lakshadweep in 1973.
- Headquarter- Kavaratti Island
- Pitti Bird Sanctuary is in Lakshadweep
Andaman and Nicobar Island
- Located in the Bay of Bengal.
- Indira Point is located in great Nicobar.
- Group of island 200
- Capital- Portblair
India as a geographical unit
India’s physical divisions are interrelated and interdependent. mountains play an important role in causing rain in the Northern Plains. It also protects India from cold winds. This reason is important for large forest and water power resources.
Northern Plains are the most important producer of Agricultural Products.
The peninsular plateau is important for the mineral resources.
The coastal plains are also important for Agricultural Products. The coastal region and Island groups provide sites for fishing and Port activities .
Thus, inspite of the physical diversity there is unity in India.
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