Physical Features of India

Chapter summary

India is unique among the world's countries in the extraordinary variety of its physical features — towering young fold mountains in the north, vast alluvial plains in the heartland, ancient plateaus in the south, a desert in the west, palm-fringed coastal plains, and tropical islands in two seas. This chapter explains how this diversity came about.

The chapter's central insight is that physical features are not static — they are the result of geological processes operating over millions of years. The Himalayas are young, formed by ongoing collision of plates. The Peninsular Plateau is ancient — its rocks date to over 3 billion years. The Northern Plains are recent — depositional work by rivers within the last few hundred thousand years. The Indian Desert was once a part of the ancient Tethys Sea.

The chapter then walks through the six physiographic divisions systematically — their location, formation, sub-divisions, key features, and economic significance. Each region has been shaped by a distinct geological process, and each plays a distinct role in Indian agriculture, settlement, and economy.

Plate tectonics and how India came to look this way

The Earth's outer shell — the lithosphere — is broken into about a dozen large pieces called tectonic plates. These plates float on the partially molten mantle below and move at speeds of a few centimetres per year. India's geological story is essentially the story of one such plate: the Indian Plate.

Around 200 million years ago, the Indian Plate was part of the ancient supercontinent of Gondwanaland, in the southern hemisphere, alongside Africa, Antarctica, Australia and South America. Around 50 million years ago, Gondwanaland broke up, and the Indian Plate began drifting northward. Around 50 million years ago, it collided with the Eurasian Plate.

The collision had three major consequences:

1. The sediments in the Tethys Sea between the two plates were compressed and folded upward, forming the Himalayas.
2. The southern part of the Indian Plate (the Peninsular Plateau) was pushed up but remained largely unfolded — preserving its ancient rocks.
3. A long, narrow foredeep formed at the foot of the Himalayas, which was gradually filled by sediments brought down by rivers — becoming the Northern Plains.

The collision is still ongoing. The Indian Plate continues to push northward at about 5 cm per year, causing the Himalayas to continue rising at about 1 cm per year. This is also why the Himalayan region is seismically active — major earthquakes (Kashmir 2005, Nepal 2015, Sikkim 2011) all reflect ongoing plate stress.

1. The Himalayan Mountains

The three parallel ranges

The Himalayas consist of three almost parallel ranges, with their longitudinal valleys lying in between:

Regional sub-divisions

The Himalayas are also divided regionally from west to east into:

• Punjab Himalayas (between Indus and Sutlej) — known as Kashmir or Himachal Himalayas regionally.
• Kumaon Himalayas (between Sutlej and Kali) — includes parts of Uttarakhand.
• Nepal Himalayas (between Kali and Tista).
• Assam Himalayas (between Tista and Brahmaputra) — includes Arunachal Pradesh.

Beyond the main Himalayas to the south lie the Purvanchal — the eastern extension running through the Northeast: Patkai Hills, Naga Hills, Manipur Hills, Mizo Hills. These are composed of strong sandstones and limestone.

2. The Northern Plains

The three sections

• The Punjab Plain — formed by the Indus and its tributaries (Jhelum, Chenab, Ravi, Beas, Sutlej). The land is mostly made up of "doabs" — the term means "two waters" referring to land between two rivers.
• The Ganga Plain — between Ghaggar and Tista rivers. Covers Haryana, Delhi, UP, Bihar, parts of Jharkhand and West Bengal. Lower Ganga forms the Sundarban Delta — the world's largest.
• The Brahmaputra Plain — Assam region. The Brahmaputra carries enormous silt loads (highest in the world after Yangtze), causing both fertility and frequent flooding.

Four longitudinal divisions of the Plains

According to the variations in relief features, the Northern Plains can be divided into four regions running parallel to the Himalayas:

1. Bhabar — narrow belt (8-16 km wide) of pebbles and boulders deposited by rivers descending from mountains. Streams disappear underground.
2. Terai — wet, swampy belt south of Bhabar where underground streams re-emerge. Originally forested, now mostly cleared for agriculture.
3. Bhangar — older alluvium above the floodplains; contains "kankar" (calcareous concretions).
4. Khadar — newer alluvium in the floodplains, renewed annually by floods. Most fertile soil.

3. The Peninsular Plateau

Two main divisions

The Central Highlands — north of the Narmada river. Composed of the Aravalli Range (one of the oldest mountain systems in the world, much eroded), the Vindhyan Range, the Satpura Range, the Maikal Range. Major rivers: Chambal, Sind, Betwa, Ken — all flowing northeast and joining the Yamuna or Ganga.

The Deccan Plateau — south of the Narmada. A triangular landmass bounded by Western Ghats in the west and Eastern Ghats in the east. The plateau slopes gently to the east, which is why most of its rivers (Godavari, Krishna, Kaveri, Mahanadi) flow east into the Bay of Bengal.

The Western and Eastern Ghats

The Deccan Trap — black soil region in the northwest of the Deccan Plateau — was formed by volcanic activity around 60-65 million years ago. The thick black soil here (called regur) is rich in lime and magnesium and ideal for cotton cultivation.

4. The Indian Desert

The Thar Desert has crescent-shaped dunes called barchans and longitudinal dunes that move with the wind. Vegetation is sparse; vegetation includes xerophytic plants like the khejri tree. The only river is the Luni, which flows only after rains and disappears in the Rann of Kutch.

5. The Coastal Plains

The Western Coastal Plain

Narrow (50-100 km wide). Lies between the Western Ghats and the Arabian Sea. Divided into:

• Konkan Coast (Mumbai to Goa)
• Kannad Plain (Goa to Mangalore)
• Malabar Coast (Mangalore to Kanyakumari)

The coast has many natural harbours — Mumbai, Mormugao, New Mangalore, Cochin. Backwaters (kayals) in Kerala are famous tourist attractions.

The Eastern Coastal Plain

Wider (100-130 km wide). Lies between the Eastern Ghats and the Bay of Bengal. Divided into:

• Northern Circars / Utkal Coast (Mahanadi to Krishna delta)
• Coromandel Coast (Krishna delta to Kanyakumari)

The coast features deltas of major rivers — Mahanadi, Godavari, Krishna, Kaveri. The largest is the Sundarban Delta formed by the Ganga-Brahmaputra. Lake Chilika is Asia's largest brackish water lake.

6. The Islands

India has two major island groups:

Lakshadweep Islands (Arabian Sea)

• 36 coral islands, of which only 10 are inhabited. Smallest UT by area.
• Made of coral atolls — built by colonies of tiny marine creatures over thousands of years.
• Capital: Kavaratti.

Andaman and Nicobar Islands (Bay of Bengal)

• Larger and more numerous than Lakshadweep — about 572 islands, of which 38 are inhabited.
• Believed to be the elevated portions of submarine mountain ranges connecting the Arakan Yoma in Myanmar with the Sumatran Archipelago.
• Capital: Port Blair.
• Hosts Indian Navy's tri-services command — strategic importance.
• Indira Point (Great Nicobar) is the southernmost point of the Indian Union.

NCERT exercise Q&A (with explanations)

UPSC / MPSC previous year questions on this chapter