Introduction
India is known for its diverse landforms. From the towering Himalayan mountains to the vast Northern plains, the dry deserts of Rajasthan to the lush coastal areas, India has almost every major physical feature found on Earth.
Why are these features important?
- Agriculture and livelihood
- Weather and climate
- Natural resources
- Human settlements
How Were These Physical Features Formed?
Theory of Plate Tectonics
| Type of Plate Boundary | Movement | Effect |
|---|---|---|
| Convergent | Plates come towards each other | Mountains form (e.g., Himalayas) |
| Divergent | Plates move apart | New landforms form (ridges, valleys) |
| Transform | Plates slide past each other | Earthquakes occur |
Question: What is the Theory of Plate Tectonics? Answer: It explains the movement of Earth's lithospheric plates and how they shape the surface, forming mountains, valleys, and causing earthquakes.
Gondwana Land: The Origin
- Millions of years ago, India was part of Gondwana land, a supercontinent in the southern hemisphere.
- It slowly drifted northward and collided with Eurasian plate, forming the Himalayas and the Northern Plains.
Major Physical Divisions of India
| Division | Key Feature |
|---|---|
| Himalayan Mountains | Lofty young fold mountains |
| Northern Plains | Fertile alluvial plains |
| Peninsular Plateau | Ancient igneous rocks |
| Indian Desert | Arid region with sand dunes |
| Coastal Plains | Narrow plains near coasts |
| Islands | Coral/volcanic island groups |
The Himalayan Mountains
- Form India's northern boundary, stretching 2,400 km west to east.
- Width varies: 400 km (Kashmir) to 150 km (Arunachal Pradesh).
- Young, active fold mountains made from sedimentary rocks.
Longitudinal Divisions of Himalayas
| Range | Altitude | Features |
|---|---|---|
| Himadri (Greater Himalayas) | Avg. 6000 m | Highest peaks (e.g., Mt. Everest), snow-covered, glaciers, granite core |
| Himachal (Lesser Himalayas) | 3,700–4,500 m | Pir Panjal, Dhauladhar ranges, famous valleys (Kullu, Kangra), hill stations |
| Shiwaliks (Outer Himalayas) | 900–1100 m | Made of unconsolidated sediments; includes Duns like Dehra Dun |
Regional Divisions (West to East)
| Region | Rivers Between |
|---|---|
| Punjab Himalayas | Indus – Satluj |
| Kumaon Himalayas | Satluj – Kali |
| Nepal Himalayas | Kali – Tista |
| Assam Himalayas | Tista – Dihang |
Purvanchal Hills (Eastern Hills)
- Located in Northeast India, south of Brahmaputra.
- Includes Patkai, Naga, Manipur, and Mizo hills.
- Made of sandstone; covered with dense forests.
The Northern Plains
- Formed by deposition of alluvium from Indus, Ganga, and Brahmaputra rivers.
- Area: 7 lakh sq. km; Length: 2400 km; Breadth: 240–320 km.
- One of the most fertile and densely populated regions.
Question: Why are the Northern Plains so densely populated? Answer: Because of their fertile soil, abundant water supply, and flat terrain, which support agriculture and human settlements.
Divisions of the Northern Plains
| Region | Location |
|---|---|
| Punjab Plains | Formed by Indus & tributaries |
| Ganga Plains | From Ghaggar to Teesta (U.P., Bihar, W.B.) |
| Brahmaputra Plains | Assam region |
Based on Relief
| Zone | Description |
|---|---|
| Bhabar | Pebbly belt near Shiwaliks; rivers disappear here |
| Terai | Marshy, re-emergence of rivers, dense forests |
| Bhangar | Older alluvium, slightly elevated, contains kankar |
| Khadar | Newer alluvium, highly fertile, floodplain |
The Peninsular Plateau
- Oldest landmass of India; made of igneous and metamorphic rocks.
- High tableland with gentle hills and valleys.
Question: What makes the Peninsular Plateau unique? Answer: It is the oldest landmass in India, made of igneous and metamorphic rocks, and features high tablelands, hills, and valleys.
Divisions of Peninsular Plateau
| Region | Description |
|---|---|
| Central Highlands | North of Narmada; includes Malwa, Bundelkhand, Baghelkhand |
| Deccan Plateau | South of Narmada; triangular; higher in west, slopes eastwards |
- Chotanagpur Plateau: Drained by Damodar River.
- Meghalaya Plateau: Separated from Chotanagpur; includes Garo, Khasi, Jaintia hills.
The Ghats (Edges of Deccan Plateau)
| Feature | Western Ghats | Eastern Ghats |
|---|---|---|
| Continuity | Continuous | Discontinuous |
| Height | Higher (900–1600 m) | Lower (avg. 600 m) |
| Origin of Rivers | Yes (Godavari, Krishna, Kaveri) | No major rivers originate here |
| Rainfall Type | Orographic (heavy monsoon) | Rain mainly from NE monsoon |
| Peaks | Anai Mudi, Doda Betta | Mahendragiri |
The Indian Desert
- Located west of Aravallis (Rajasthan).
- Sandy plain with sand dunes (barchans).
- Low rainfall (<150 mm/year), arid climate.
- Only major river: Luni.
The Coastal Plains
Narrow coastal strips along the Arabian Sea (West Coast) and the Bay of Bengal (East Coast).
Question: What is the significance of India's coastal plains? Answer: They support fishing, trade, and agriculture, and are home to major ports and river deltas.
West Coast Divisions
- Konkan Coast (Mumbai–Goa)
- Kannad Plain
- Malabar Coast
East Coast Divisions
- Northern Circar
- Coromandel Coast
- Major river deltas: Mahanadi, Godavari, Krishna, Kaveri.
- Chilika Lake: India's largest saltwater lagoon (Odisha).
The Islands
Lakshadweep Islands (Arabian Sea)
- Coral origin, small islands
- Area: 32 sq. km
- HQ: Kavaratti
- Pitti Island has a bird sanctuary.
Andaman & Nicobar Islands (Bay of Bengal)
- Volcanic origin; more in number and size.
- Divided into Andaman (north) and Nicobar (south).
- Includes India's only active volcano: Barren Island
- Rich biodiversity and strategic importance.
Importance of India's Physical Features
| Physical Feature | Importance |
|---|---|
| Mountains | Forests, water sources, biodiversity |
| Plains | Agriculture, transport, dense population |
| Plateaus | Minerals, industrial development |
| Deserts | Tourism, solar energy, camel trade |
| Coasts | Fishing, ports, trade |
| Islands | Tourism, biodiversity, strategic defense |