CBSE Class 9 Social Science Geography Chapter 2 Notes: Physical Features of India

Must-Remember Key Points

• India's landmass has been formed during different geological periods through processes like weathering, erosion, deposition, and tectonic activity.
• The Theory of Plate Tectonics explains the formation of most of India's physical features, including the Himalayas.
• India is divided into six major physiographic divisions: The Himalayan Mountains, The Northern Plains, The Peninsular Plateau, The Indian Desert, The Coastal Plains, and The Islands.
• The Himalayas are geologically young and structurally fold mountains that run in a west-east direction.
• The Northern Plain is formed by the interplay of three major river systems: the Indus, the Ganga, and the Brahmaputra, along with their tributaries. It is composed of fertile alluvial soil.
• The Peninsular Plateau is a tableland composed of old crystalline, igneous, and metamorphic rocks. It is the oldest landmass of India.
• The Western Ghats are higher and more continuous than the Eastern Ghats.
• The Indian Desert (Thar Desert) lies towards the western margins of the Aravali Hills and receives very low rainfall (below 150 mm per year).
• India has two major island groups: the Lakshadweep Islands in the Arabian Sea (coral islands) and the Andaman and Nicobar Islands in the Bay of Bengal (elevated portion of submarine mountains).

Key Terms for Exams

Plate Tectonics

The theory that Earth's outer shell is divided into several large, rigid plates that glide over the mantle. Their movement causes earthquakes, volcanoes, and the formation of mountains.

Gondwana Land

An ancient supercontinent that included India, Australia, South Africa, South America, and Antarctica as one single landmass.

Bhabar

A narrow belt, about 8 to 16 km in width, lying parallel to the slopes of the Shiwaliks where rivers deposit pebbles. Streams disappear in this region.

Terai

A wet, swampy, and marshy region south of the Bhabar belt where the streams and rivers re-emerge. It was once thickly forested.

Bhangar

The largest part of the northern plain, formed of older alluvium. It lies above the flood plains and presents a terrace-like feature. It is less fertile and contains calcareous deposits called 'Kankar'.

Khadar

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

Duns

Longitudinal valleys lying between the lesser Himalayas (Himachal) and the Shiwaliks. Examples: Dehra Dun, Kotli Dun, and Patli Dun.

Pass

A natural gap or route through a mountain range. Examples: Nathu La, Shipki La in the Himalayas.

Doab

A piece of land lying between two converging or confluent rivers. 'Do' means two and 'ab' means water.

Formation of the Himalayas and the Northern Plains

The formation of India's most prominent physical features is a fascinating story rooted in the Theory of Plate Tectonics. Millions of years ago, the landmass of India was part of the southern supercontinent called Gondwana Land. Convectional currents in the Earth's mantle caused the crust to split into a number of plates. The Indo-Australian plate, after separating from Gondwana Land, began drifting northwards.

This northward drift resulted in a massive collision with the much larger Eurasian Plate. Due to this collision, the sedimentary rocks which had accumulated in the geosyncline known as the Tethys Sea, located between the two landmasses, were uplifted and folded. This process of folding resulted in the formation of the mountain system we know today as the Himalayas. These are geologically young and structurally unstable mountains.

Simultaneously, the Himalayan uplift and the subsidence of the northern flank of the Peninsular Plateau created a large basin. Over millions of years, this depression was gradually filled with sediments deposited by the rivers flowing from the mountains in the north (Indus, Ganga, Brahmaputra) and the plateau in the south. This extensive deposition of alluvium led to the creation of the vast, flat, and fertile Northern Plains of India.

The Six Major Physiographic Divisions

Comparison: Western Ghats vs. Eastern Ghats

Exam Tip: Master the Map

Map-based questions are a guaranteed feature from this chapter. You must practice locating and labeling key features. Create a checklist:

• Mountain Ranges: Karakoram, Zaskar, Pir Panjal, Shiwalik, Aravali.
• Mountain Peaks: K2, Kanchenjunga, Anai Mudi.
• Plateaus: Deccan Plateau, Chotanagpur Plateau, Malwa Plateau.
• Coastal Plains: Konkan, Malabar, Coromandel, Northern Circar.
• Ghats: Western Ghats and Eastern Ghats.

Use a blank political map of India and practice marking these at least 3-4 times before the exam. This will secure you easy marks.

Practice Questions with Solutions

• Name the three parallel ranges of the Himalayas in order of their location from north to south. 1. The Great or Inner Himalayas (Himadri) 2. The Lesser Himalaya (Himachal) 3. The Outer Himalayas (Shiwaliks)
• What is the difference between Bhangar and Khadar soil? Bhangar is the older alluvial soil found away from the river beds, it is less fertile and contains 'kankar' nodules. Khadar is the newer alluvial soil found in floodplains, it is very fertile and renewed annually.
• Which two geological features make up the Peninsular Plateau? The Peninsular Plateau consists of two broad divisions: The Central Highlands and The Deccan Plateau.
• How are the Andaman & Nicobar Islands different from the Lakshadweep Islands in their formation? The Andaman & Nicobar Islands are an elevated portion of submarine mountains, whereas the Lakshadweep Islands are composed of small coral atolls.

Frequently Asked Questions

Frequently Asked Questions