Himalayan Mountain System
Formation and Structure
The Himalayas are fold mountains formed by the collision of the Indian Plate with the Eurasian Plate approximately 50 million years ago. They are the world's youngest and highest mountain range.
Three parallel ranges (west to east):
| Range | Local Name | Key Features |
|---|---|---|
| Greater Himalayas (Himadri) | Mahabharata Lekh | Average elevation 6,000 m; highest peaks; permanently snow-covered |
| Middle Himalayas (Himachal) | Pir Panjal, Dhauladhar | 3,700–4,500 m; hill stations (Shimla, Mussoorie, Darjeeling) |
| Outer Himalayas (Shiwaliks) | Sub-Himalayan range | 900–1,100 m; youngest; duns (longitudinal valleys: Dehradun, Patlidun) |
Highest peaks:
- Mt. Everest: 8,849 m — Nepal (highest in world)
- K2 (Godwin Austen): 8,611 m — Pakistan-administered Kashmir (highest in India's claim area)
- Kangchenjunga: 8,586 m — India-Nepal border (highest peak fully in India's territory)
- Nanda Devi: 7,817 m — Uttarakhand (highest peak entirely within India)
Significance of the Himalayas
- Climate barrier: Blocks cold Central Asian winds in winter; forces monsoon winds upward causing heavy rainfall
- River source: Perennial rivers (Ganga, Brahmaputra, Indus) originate here — sustained by glaciers
- Natural boundary: Separates India from China and Central Asia
- Biodiversity: Temperate and alpine forests, snow leopard, Himalayan brown bear, yak
- Defence: Natural barrier against land invasion from north
The Northern Plains
Formation
Formed by alluvial deposits from Himalayan rivers — Indus, Ganga, Brahmaputra — over millions of years. The world's most extensive alluvial plain. About 2,400 km long, 240–320 km wide.
Types of Alluvial Soil
| Type | Location | Features |
|---|---|---|
| Bhangar | Old alluvial (elevated terraces) | Contains kankar (nodular limestone), less fertile |
| Khadar | New alluvial (near riverbeds) | Fresh deposits, highly fertile, renewed every flood |
Sub-divisions
1. Punjab Plain (Indus system): Doabs between five rivers (hence "Punj-ab" = five waters) 2. Ganga Plain: Largest; includes Uttar Pradesh, Bihar, West Bengal 3. Brahmaputra Plain (Assam Valley): Narrow, prone to floods; Brahmaputra changes course regularly
Significance
- Most densely populated region in India
- Highest agricultural productivity: wheat, rice, sugarcane, cotton
- Major cities: Delhi, Lucknow, Patna, Kolkata, Kanpur, Varanasi
The Peninsular Plateau
Deccan Plateau
The oldest landmass of India, part of the ancient Gondwanaland supercontinent. Bounded by:
- North: Vindhya Range and Satpura Range
- West: Western Ghats
- East: Eastern Ghats
Deccan Traps: Northwestern Deccan (Maharashtra, parts of MP, Karnataka) covered by volcanic basalt from massive lava eruptions 65–66 million years ago. Forms black cotton soil (regur) — ideal for cotton.
Central Highlands
- Malwa Plateau: Part of Madhya Pradesh, north of Vindhyas, drained by Chambal and Betwa
- Chhota Nagpur Plateau: Jharkhand — rich in minerals (coal, iron ore, mica); "Ruhr of India"
- Meghalaya Plateau: Separated from main plateau by the Garo-Rajmahal gap
Western Ghats (Sahyadri)
- Continuous escarpment, 1,600 km from the Tapi river (Gujarat) to Kanyakumari
- Average elevation: 900–1,500 m
- Highest point: Anamudi (2,695 m, Kerala) — highest peak in India south of the Himalayas
- Key passes (ghats): Thal Ghat, Bhor Ghat (Maharashtra), Palakkad Gap (only major break in Western Ghats — allows Arabian Sea moisture into Tamil Nadu interior)
- UNESCO World Heritage Site; global biodiversity hotspot
Eastern Ghats
- Discontinuous ranges, cut by rivers (Mahanadi, Godavari, Krishna, Cauvery)
- Lower elevation (600 m average)
- Highest peak: Jindhagada (1,690 m, Andhra Pradesh); in Tamil Nadu: Servarayan hills (Yercaud)
Important Hills of Tamil Nadu
| Hill Range | District | Significance |
|---|---|---|
| Nilgiri Hills | Ooty | Highest in TN (Doddabetta, 2,637 m); tea, coffee |
| Palani Hills | Kodaikanal | Average 2,000 m; Kodaikanal Lake |
| Anamalai Hills | Valparai, Pollachi | Anamalai Tiger Reserve |
| Javadi Hills | Vellore, Tirupattur | Deciduous forest |
| Kalrayan Hills | Salem, Villupuram | Tribal areas |
| Kolli Hills | Namakkal | Medicinal plants; waterfalls |
| Shevaroy Hills | Salem | Yercaud hill station |
The Indian Desert (Thar Desert)
- Location: Western Rajasthan, parts of Gujarat; extends into Pakistan (Sindh)
- Area: ~2,00,000 sq km
- Annual rainfall: < 250 mm (some areas < 100 mm)
- Vegetation: sparse thorny scrub, cacti, khejri tree (state tree of Rajasthan)
- River: Luni — only significant river; drains into Rann of Kutch
- Indira Gandhi Canal (Rajasthan Canal): Brings water from Harike Barrage (Sutlej-Beas confluence) in Punjab to irrigate Rajasthan desert
Coastal Plains
Western Coastal Plain
Narrow (50–80 km), between Western Ghats and Arabian Sea. No major deltas — rivers are short and swift.
Sub-divisions (north to south):
- Konkan Coast (Maharashtra, Goa)
- Kannad Coast (Karnataka)
- Malabar Coast (Kerala)
Backwaters (Lagoons): Kerala's famous backwaters — Vembanad Lake, Ashtamudi Lake. Formed by sand bars deposited by sea waves blocking river mouths.
Eastern Coastal Plain
Wider (100–120 km), between Eastern Ghats and Bay of Bengal. Major river deltas (Mahanadi, Godavari, Krishna, Cauvery).
Sub-divisions (north to south):
- Utkal Coast (Odisha)
- Northern Circars (Andhra Pradesh)
- Coromandel Coast (Andhra Pradesh and Tamil Nadu)
Tamil Nadu coast (Coromandel Coast):
- Length: 1,076 km — third longest coastline of any Indian state
- Major ports: Chennai (Kamarajar Port), Tuticorin (VO Chidambaranar Port), Nagapattinam
- Cauvery delta: fertile rice-growing region; called "granary of Tamil Nadu"
- Pulicat Lake: 2nd largest brackish water lagoon in India (straddles TN-AP border)
- Gulf of Mannar: between Tamil Nadu and Sri Lanka; coral reefs, dugong, sea grass
Islands
Andaman and Nicobar Islands
- Location: Bay of Bengal; 700 km south of mainland
- 572 islands; only 37 inhabited
- Highest peak: Saddle Peak (732 m, North Andaman)
- Capital: Port Blair
- Indira Point (Great Nicobar): southernmost point of India (6°45'N)
- Barren Island: India's only active volcano (in Andaman Sea)
- Narcondam Island: Dormant volcano
Lakshadweep Islands
- Location: Arabian Sea; 200–440 km west of Kerala coast
- 36 islands, 12 atolls, 3 reefs; only 10 inhabited
- Capital: Kavaratti
- Minicoy Island: Southernmost; only island with Malayalam-speaking Mahl community
- Coral islands — no streams or rivers; freshwater from rainwater and wells
- India's smallest Union Territory by area (32 sq km)
Board Exam Tips
- Physiographic divisions: 6 divisions — Himalayas, Northern Plains, Peninsular Plateau, Thar Desert, Coastal Plains, Islands.
- Anamudi (2,695 m) = highest peak south of Himalayas in India. Often confused with Doddabetta (2,637 m, highest in Tamil Nadu's Nilgiris).
- Western Ghats = UNESCO World Heritage + biodiversity hotspot. Eastern Ghats = not.
- Palakkad Gap = only major break in Western Ghats — very frequently asked.
- Barren Island = India's only active volcano (Andaman & Nicobar).
- Indira Point = southernmost point of India (Great Nicobar island, not mainland Kanyakumari).
- Pulicat Lake = 2nd largest brackish water lagoon (1st = Chilika Lake, Odisha).
Frequently Asked Questions
India has six major physiographic divisions: (1) The Himalayan Mountains, (2) The Northern Plains (Indo-Gangetic Plain), (3) The Peninsular Plateau (Deccan Plateau), (4) The Indian Desert (Thar Desert), (5) The Coastal Plains (Eastern and Western), (6) The Islands (Andaman & Nicobar, Lakshadweep).