Class 9 Geography Chapter 2 Notes - Physical Features of India

Major Physiographic Divisions

India's major physiographic divisions include distinct landforms such as mountains, plateaus, plains, deserts, and coastal regions, each contributing to the country's diverse geography.

Let's discuss each of them individually:

1. The Himalayan Mountains

The Himalayas are young fold mountains located in northern India. They stretch in a west-east direction from the Indus River to the Brahmaputra River. The range forms an arc covering about 2,400 km. The width varies, being 400 km in Kashmir and narrowing to 150 km in Arunachal Pradesh.

Himalayas on map

Three Parallel Ranges

The Himalayas consist of three parallel ranges:

• Great Himalayas (Inner Himalayas): Highest peaks, made of granite, and snow-covered year-round.
• Lesser Himalayas (Himachal): Composed of compressed and altered rocks.
• Shiwaliks: The outer-most range, formed by river-borne sediments.

Valleys and Duns: Valleys are located between the Lesser Himalayas and Shiwaliks, known as Duns, which are fertile regions.

Regional Division: The Himalayas are divided into several regions based on river valleys: Punjab, Kashmir, Himachal, Kumaon, Nepal, and Assam Himalayas.

Eastern Extension (Purvachal Hills)

• The Brahmaputra River marks the eastern boundary.
• Beyond the Dthang gorge, the range bends south, forming the Purvachal hills, including Patkai, Naga, Mizo, and Manipur hills.
• These hills are made of strong sandstone and are densely forested.

2. The Nothern Plain

The northern plain is formed by the interplay of the Indus, Ganga, and Brahmaputra rivers. The plain is formed by the deposition of alluvium over millions of years. It is a fertile and densely populated part of India. The rivers in the lower course form riverine islands and distributaries.

Divisions of Northern Plains:
(i) Punjab Plains: The western part of the Northern Plain, is formed by the Indus and her 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 Himalayas. This section of the plain is dominated by the doabs.
(ii) Ganga Plain: Extends between Ghaggar and Teesta rivers. it is spread over the states of north India, Haryana, Delhi, U.P., Bihar, party Jharkhand, and West Bengal.
(iii) Brahmaputra Plain: Lies in the east of Ganga plain, particularly in Assam.

Divisions of Northern Plains

• Varied Topography: The Northern Plains are not completely flat and have diverse landforms with variations in river features
• Divisions Based on River Features: The plains can be divided into four distinct regions based on river deposit patterns and landforms.
• Bhabar Belt: The Bhabar is a narrow belt where rivers deposit pebbles. This region lies at the foothills of the Himalayas.
• Terai Region: South of the Bhabar is the Terai, a wet and marshy region. The area used to be densely forested but has been largely cleared for agriculture. Dudhwa National Park is situated in this region.
• Bhangar: Older Alluvium: The largest part of the Northern Plains consists of Bhangar, which is made up of older alluvium. This region contains calcareous deposits known as Kankar.
• Khadar Fertile Floodplains: The Khadar are the fertile floodplains of rivers, renewed annually by river deposits, making them highly suitable for agriculture.

3. The Peninsular Plateau

The Peninsular plateau is a tableland composed of old crystalline, igneous, and metamorphic rocks. It was formed due to the breaking and drifting of the Gondwana land. The plateau has broad and shallow valleys and rounded hills. It consists of two divisions: the Central Highlands and the Deccan Plateau.

The Central Highlands

• Location and Boundaries: The Central Highlands lie to the north of the Narmada River and include the Malwa Plateau. The region is bounded by the Vindhyan Range to the north, the Satpura Range to the south, and the Aravalli Range to the northwest.
• Slope and River Flow: The slope of the Central Highlands is from southwest to northeast, as indicated by the flow of rivers. The highlands are wider in the west and narrow down towards the east.
• Extensions of the Central Highlands: The Bundelkhand and Baghelkhand are the eastern extensions of this region. The Chotanagpur Plateau, further east, is drained by the Damodar River.

The Deccan Plateau

• Location and Boundaries: The Deccan Plateau lies to the south of the Narmada River, flanked by the Satpura Range in the north. The plateau slopes gently eastward and is higher in the west.
• Northeastern Extensions: The Meghalaya, Karbi-Anglong Plateau, and North Cachar Hills form the northeastern extensions of the Deccan Plateau. The Garo, Khasi, and Jaintia Hills are prominent hill ranges in this region.
• Western and Eastern Edges: The Western Ghats and Eastern Ghats mark the western and eastern boundaries of the Deccan Plateau, respectively.
  
  

4. The Indian Desert

The Indian desert is located towards the western margins of the Aravall Hills. It is an undulating sandy plain covered with sand dunes. The region receives very low rainfall, below 150 mm per year.

• The desert has an arid climate with low vegetation cover.
• Streams appear during the rainy season but disappear into the sand as they don't reach the sea.
• The Luni river is the only large river in this region.
• Barchans (crescent-shaped dunes) cover larger areas, while longitudinal dunes are more prominent near the Indo-Pakistan boundary.
• Visitors to Jalsalmer can see a group of barchans.

5. The Coastal Plains

The Peninsular plateau is flanked by narrow coastal strips on the Arabian Sea and Bay of Bengal. The western coast consists of three sections: Konkan, Kannad Plain, and Malabar coast.

• The plains along the Bay of Bengal are wide and level.
• The northern part is called the Northern Circar and the southern part is known as the Coromandel Coast.
• Large rivers such as Mahanadi, Godavari, Krishna, and Kaveri have formed extensive deltas on this coast.
• Lake Chilika is an important feature along the eastern coast.

6. The Islands

India has a vast mainland and two groups of islands. The Lakshadweep Islands group is located close to the Malabar coast of Kerala and is composed of small coral islands. The Andaman and Nicobar Islands are larger and more scattered, located in the Bay of Bengal.

• The Andaman Islands are in the north and the Nicobar Islands are in the south
• Both island groups have diverse flora and fauna and are of strategic importance
• Each physiographic unit in India has unique features that complement each other and contribute to the country's natural resources
• Mountains provide water and forest wealth, northern plains are granaries, plateaus have minerals, coastal regions and island groups are important for fishing and port activities
• The diverse physical features of India have great potential for development.

Difficult Words

1. Fold Mountains: These are mountains that are formed primarily through the effects of folding on layers within the upper part of the Earth's crust. The Himalayas are an example of young fold mountains formed from the collision of tectonic plates.

2. Alluvial Deposits: Sediments deposited by rivers or floodwaters. In the context of the Northern Plains of India, these deposits create fertile land ideal for agriculture.

3. Igneous and Metamorphic Rocks: Igneous rocks are formed from the solidification of molten magma. Metamorphic rocks have been transformed by heat, pressure, or other natural processes from another type of rock.

4. Tableland: A plateau or a flat-topped area that is elevated significantly above the surrounding area.

5. Gondwana Land: A supercontinent that existed from the Late Paleozoic into the Mesozoic era. It later broke up to form continents including Africa, South America, Australia, and India.

6. Bhabar and Terai: Bhabar refers to a narrow belt of land at the foothills of the Himalayas along the Ganges River, characterized by pebbles and porous soil. Terai is the marshy land just south of the Bhabar belt, known for its rich biodiversity and fertile soil.

7. Deccan Trap: A large igneous province located on the Deccan Plateau of west-central India and one of the largest volcanic features on Earth. It consists of multiple layers of solidified flood basalt that are more than 2,000 meters thick over an area of 500,000 square kilometers.

8. Aravalli Range: One of the oldest mountain ranges in India, running northeast to southwest across Rajasthan in western India.

9. Duns: Valleys lying between the Lesser Himalayas and the Shiwaliks, filled with alluvial deposits.

10. Kankar: Calcareous or calcite nodules found in the alluvial or sedimentary soils in the dryer parts of India.

11. Deccan Plateau: A large plateau in India, making up most of the southern part of the country. It is made up of ancient crystalline, igneous, and metamorphic rocks.

12. Coromandel Coast: The southeastern coast of India along the Bay of Bengal, from Cape Comorin (Kanyakumari) in the south to False Divi Point in the north in Andhra Pradesh.

13. Coral Islands: Islands formed from coral detritus and associated organic material. They typically occur in tropical and subtropical areas, such as the Lakshadweep Islands off the southwest coast of India.