Revision notes class 9th S.st (Geography) Ch:2

   Physical features of India

                 Chapter: 2

🔆Introduction

 

🔅India has all major physical features of the earth , i.e. mountains , plains , deserts , plateaus and Islands.

🔅In India the soil colour varies from place to place as it is formed from different types of rocks.

🔅India is a large land mass formed during different geological periods.

🔅India's relief features are outcome of other processes like weathering , erosion and deposition.

🔅India has varied physical features whose formation can be explained on the basis of the 'Theory of Plate Tectonics'.

🔅According to the theory of Plate Tectonics the 7 major and minor plates that form the earth's crust keep moving , causing stress and thus leading to folding , faulting and volcanic activity.

🔅Plates can have convergent ,divergent and transform boundaries.

🔅India's Peninsular part is made from one of the oldest landmass of the world's 'Gondwana land'. It was a single land mass comprising of India ,Australia ,South Africa ,South America and Antarctica.

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

1)The Himalayan mountains

2)The Northern plains

3)The Peninsular plateau

4)The Indian desert

5)The Coastal plains

6)The Islands

🔆The Himalayan Mountains

🔅The Himalayas are young-fold mountains which are the loftiest and one of the most rugged mountains barriers of the world.

🔅The Himalayas 2400 km long , 400 kilometre to 150 kilometre from Kashmir to Arunachal Pradesh respectively.

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

🔅Great or Inner Himalayas also called Himadri. It is the highest mountains range with average height 6000 m.

🔅The range lying to the south of the Himadri forms the most rugged mountains system and is known as Himachal or lesser Himalaya.

🔅Middle Himalayas or Himachal. The altitude varies  between 3700 and 4500 m. It includes range like Pir panjal , Dhauladhar and Mahabharat.

🔅Outer Himalayas or Shivalik. It is outermost range with 900 to 1100 m average altitude.

🔅The outermost range of the Himalayas is called the siwaliks. The extend over a width of 10-50 km and have an altitude varying between 900 and 1100 metres.

🔅The longitudinal valley lying between lesser Himalaya and the Shivaliks are known as Duns. Dehradun , Kotli Dun and Patli Dun are some of the well- known Duns.

             The Himalayas   

🔅The Himalayas can be divided into four sections:

🔅Punjab Himalayas : The part of Himalayas lying between Indus and satluj has been traditionally known as Punjab Himalaya but it is also known regionally as Kashmir and Himachal Himalaya from west to east respectively.

🔅Kumaon Himalayas : The part of the Himalayas lying between satluj and Kali rivers is known as Kumaon Himalayas.

🔅The Kali and Teesta rivers demarcate the Nepal Himalayas and the part lying between Teesta and Dihang rivers is known as Assam Himalayas.

🔅The Purvanchal comprises the Patkai hills , the Naga hills , the Manipur hills and the Mizo hills.

🔅Assam Himalayas (Eastern Himalayas)- Between Tista and the Dihang (Tsangpo).

                 Mizo Hills

🔆The Northern plain

🔅The Northern plain has been formed by the interplay of the three major river systems namely - the Indus , the Ganga and the Brahmaputra along with their tributaries. The plane is formed of alluvial soil.

🔅It spreads over an area of 7 lakh square kilometre. The plain being about 2400 km long and 240 to 320 km broad , is a densely populated physiographic division.

🔅The rivers in their lower course split into numerous channels due to the deposition of silt. These channels are known as distributaries.

🔅The rivers that flow to the plains from the mountains are involved in depositional work.

🔅The Indus and its tributaries - the Jhelum , the Chenab , the Ravi , the Beas and the Satluj originate in the Himalaya.

🔅'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.

🔅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 particularly in Assam lies the Brahmaputra plain.

🔆The Northern plains can be divided into four regions.

🔅The rivers, after descending from the mountains deposit pebbles in a narrow belt of about 8 to 16 kilometre in width lying parallel to the slopes of the Shivaliks. It is known as Bhabar.

🔅The streams and rivers re - emerge and create a wet , swampy and marshy region known as terai.

🔅The largest part of the northern plain is  formed of older alluvium. It lies above the flood plains of the rivers and presents a terrace - like feature. This part is known as Bhangar.

🔅The soil  in this region contains calcareous deposits, locally known as Kankar.

🔅The newer, younger deposits of the food flood plains are called Khadar.

🔆The Peninsular Plateau

🔅The Peninsular plateau is a tableland composed of the old crystalline, igneous and metamorphic rocks.

🔅It was formed due to the breaking and drifting of the Gondwana land.

🔅The plateau consists of two broad division namely, the Central Highlands and the Deccan Plateau.

🔅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.

🔅The Central Highlands are wider in the West but narrower in the East.

🔅The eastward extension of peninsular plateau are locally known as Bundelkhand and Baghelkhand.

🔅The Chhota Nagpur plateau marks the further eastward extension, drained by the Damodar river.

🔅The Deccan plateau , a triangular mass, lies to the south of the river Narmada.

🔅Three prominent hill ranges from the west to the east are the Garo, the Khasi and the Jaintia Hills.

🔅The Western ghats and the Eastern ghats mark the Western and the eastern edges of the Deccan plateau respectively.

🔅The Western Ghats are higher than the Eastern Ghats.

🔅The average elevation is 900 -1600 metres as against 600 metres of the Eastern Ghats.

🔅The highest peaks include the Anai Mudi (2,695 metres) and the Doda Betta (2,637 metres) .

🔅Mahendragiri (1501metres) is the highest peak in the Eastern Ghats.

🔅The distinct features of the Peninsular plateau is the black soil area known as Deccan Trap.

🔆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.

🔅Luni is the only large river in this region.

🔆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 northern part of the coast is called the konkan (Mumbai -Goa), the central stretch is called the Kannad 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.

🔆The Islands

🔅The Lakshadweep Islands group lying close to the Malabar coast of Kerala. This group of island is composed of small coral islands. Earlier they were known as Laccadive, Minicoy and Amindive. In ,1973 these were named as Lakshadweep.

🔅It covers small area of 32 square kilometre.

🔅Kavaratti Island is the administrative headquarters of Lakshadweep.

🔅This Island group has great diversity of flora and fauna.

🔅The Pitti Island, which is uninhabited, has a bird sanctuary.

🔅The Andaman and Nicobar Island are an alongated chain of islands located in the Bay of Bengal.

🔅The Andaman and Nicobar Islands are an elevated portion of submarine mountains.