PHYSIOGRAPHY OF INDIA

INTRODUCTION: MEANING OF PHYSIOGRAPHY

• Physiography of a region is the result of:
  - Geological structure
  - Geomorphic processes
  - Stage of landform development
• It explains the origin, evolution and present form of landforms.
• India has extremely diverse physiography due to:
  - Plate tectonics
  - Long geological history
  - Different climatic and erosional processes

MAJOR PHYSIOGRAPHIC DIVISIONS OF INDIA

On the basis of macro relief features, India is divided into six major physiographic divisions:
1. The Northern and North-Eastern Mountains
2. The Northern Plains
3. The Peninsular Plateau
4. The Indian Desert
5. The Coastal Plains
6. The Islands

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I. THE NORTHERN AND NORTH-EASTERN MOUNTAINS (THE HIMALAYAS)
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ORIGIN AND FORMATION

• The formation of Himalayas is explained by Plate Tectonic Theory.
• According to this theory:
  - The earth’s crust is divided into several tectonic plates.
• The Himalayas and North-Eastern hills were formed due to:
  - Convergence of Eurasian Plate and Indian Plate (Gondwana landmass).
• The Indian plate moved northward and collided with Eurasian plate.
• The Tethys Sea sediments got folded and uplifted to form the Himalayas.

GENERAL FEATURES OF THE HIMALAYAS

• Geologically young and structurally folded mountains.
• Extend from Indus River in the west to Brahmaputra River in the east.
• Form a curved arc of about 2400 km length.
• Width:
  - 400 km in Kashmir
  - 150 km in Arunachal Pradesh
• The Himalayas are one of the loftiest and most rugged mountain barriers in the world.
• The altitudinal variation is greater in the eastern Himalayas.

MAIN PARALLEL RANGES OF THE HIMALAYAS

1. HIMADRI (GREAT HIMALAYAS)

• Northernmost and highest range.
• Average height: about 6000 metres.
• Contains the highest peaks of Himalayas.
• Core composed of granite.
• Perennially snow-bound.
• Asymmetrical in nature.

2. LESSER HIMALAYA (HIMACHAL)

• Lies south of Himadri.
• Altitude: 3700 to 4500 metres.
• Width: about 50 km.
• Rocks are highly compressed and altered.
• Important ranges:
  - Pir Panjal (longest and most important)
  - Dhaula Dhar
  - Mahabharat range
• Important valleys:
  - Kashmir Valley
  - Kangra Valley
  - Kullu Valley

3. SHIWALIK RANGE

• Outermost range of the Himalayas.
• Altitude: 900 to 1100 metres.
• Width: 10 to 50 km.
• Made of unconsolidated sediments brought by rivers.
• Valleys between Lesser Himalaya and Shiwaliks are called Duns.
• Examples:
  - Dehra Dun
  - Kotli Dun
  - Patli Dun

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SUBDIVISIONS OF THE HIMALAYAS (LONGITUDINAL DIVISION)
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1. KASHMIR OR NORTH-WESTERN HIMALAYAS

• Includes Karakoram, Ladakh, Zaskar and Pir Panjal ranges.
• Cold desert lies between Great Himalaya and Karakoram.
• Important features:
  - Kashmir Valley and Dal Lake
  - Glaciers: Baltoro, Siachen
• Important passes:
  - Zoji La (Great Himalaya)
  - Banihal (Pir Panjal)
  - Photu La (Zaskar)
  - Khardung La (Ladakh)
• Lakes:
  - Fresh water: Dal, Wular
  - Salt water: Pangong Tso, Moriri
• Important pilgrimages:
  - Vaishno Devi, Amarnath, Charar-e-Sharif
• Jhelum river shows meanders despite being in youth stage.
• Southern part has longitudinal valleys called Duns (Jammu Dun, Pathankot Dun).

2. HIMACHAL AND UTTARAKHAND HIMALAYAS

• Extent: Between Ravi (west) and Kali river (east).
• Drained by Indus and Ganga systems.
• All three Himalayan ranges are present.
• Spiti region is cold desert.
• Many famous hill stations:
  - Shimla, Mussoorie, Dharamshala, Kasauli, Almora, Ranikhet, Kausani.
• Important Duns:
  - Dehra Dun (largest), Chandigarh-Kalka Dun, Nalagarh Dun, Kota Dun.
• Bhotia tribes migrate to Bugyals (summer grasslands).
• Valley of Flowers is located here.
• Important pilgrimage centers:
  - Gangotri, Yamunotri, Kedarnath, Badrinath, Hemkund Sahib.

3. DARJEELING AND SIKKIM HIMALAYAS

• Located between Nepal and Bhutan Himalayas.
• Small but very high region.
• Rivers: Tista and its tributaries.
• Highest peak: Kanchenjunga.
• Population:
  - Lepchas in higher areas
  - Mixed population in lower areas
• Famous for tea plantations due to:
  - Moderate slope
  - Rich soil
  - Good rainfall
• Shiwaliks are absent.
• Duar formations present.
• Rich in flora and fauna, especially orchids.

4. ARUNACHAL HIMALAYAS

• Extend from east of Bhutan Himalayas to Diphu Pass.
• Important peaks:
  - Kangtu
  - Namcha Barwa
• Brahmaputra flows through deep gorge near Namcha Barwa.
• Important rivers:
  - Kameng, Subansiri, Dihang, Lohit
• Tribes:
  - Monpa, Daffla, Abor, Mishmi, Nishi, Naga
• Most practice Jhumming (shifting cultivation).
• Due to rugged terrain, transport is difficult.

5. EASTERN HILLS AND MOUNTAINS (PURVANCHAL)

• Extend from north to south.
• Local names:
  - Patkai Bum
  - Naga Hills
  - Manipur Hills
  - Mizo or Lushai Hills
• Barak river is important.
• Loktak Lake in Manipur is a unique feature.
• Mizoram is called Molassis Basin.
• River systems:
  - Tributaries of Brahmaputra
  - Barak-Meghna system
  - Chindwin-Irrawaddy system

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II. THE NORTHERN PLAINS
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• Formed by alluvial deposits of:
  - Indus
  - Ganga
  - Brahmaputra rivers
• Extend from west to east.
• General slope is from west to east.

SUBDIVISIONS FROM NORTH TO SOUTH

1. BHABAR

• Narrow belt (8–10 km) along Shiwalik foothills.
• Made of coarse pebbles and boulders.
• Rivers disappear here.

2. TARAI

• South of Bhabar.
• Width: 10–20 km.
• Rivers re-emerge and form marshy and swampy land.
• Dense forests and rich wildlife.

3. ALLUVIAL PLAINS

• Divided into:
  - Bhangar (old alluvium)
  - Khadar (new alluvium)
• Features:
  - Meanders, oxbow lakes, sand bars, braided channels.
• Brahmaputra plains are famous for riverine islands.
• Subject to frequent floods and shifting river courses.
• Major delta:
  - Sundarbans

• Haryana and Delhi form water divide between Indus and Ganga systems.
• Economic importance:
  - Very fertile soil
  - Supports wheat, rice, sugarcane, jute
  - Densely populated region

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III. THE PENINSULAR PLATEAU
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• Oldest and most stable part of India.
• Triangular in shape.
• Average height: 150 m to 900 m.
• Extent:
  - Delhi Ridge in northwest
  - Rajmahal Hills in east
  - Gir Range in west
  - Cardamom Hills in south
• Northeast extension:
  - Shillong and Karbi Anglong plateau

• Made of many plateau blocks:
  - Malwa, Ranchi, Hazaribagh, Palamu, Karnataka, Coimbatore etc.

• Rivers generally flow from west to east.
• Important features:
  - Rift valleys, block mountains, tors, spurs, quartzite dykes, hummocky hills
• Black soil dominates western and north-western part.
• Chambal, Bhind, Morena ravines are famous.
• Bhima fault zone is seismically active.

MAJOR DIVISIONS OF PENINSULAR PLATEAU

1. DECCAN PLATEAU

• Bounded by:
  - Western Ghats (west)
  - Eastern Ghats (east)
  - Satpura, Maikal and Mahadeo hills (north)

• Western Ghats are also called:
  - Sahyadri, Nilgiri, Anaimalai, Cardamom hills
• Average height: about 1500 m.
• Highest peak:
  - Anamudi (2695 m)
  - Dodabetta (2670 m)

• Most Peninsular rivers originate from Western Ghats.
• Eastern Ghats are discontinuous and highly eroded.
• Important ranges:
  - Javadi, Palkonda, Nallamala, Mahendragiri.
• Eastern and Western Ghats meet at Nilgiri hills.

2. CENTRAL HIGHLANDS

• Bounded by Aravalli and Satpura ranges.
• Northern boundary of Deccan Plateau.
• Old, denuded, relict mountains.
• Western part has sand dunes (Jaisalmer).
• Contains metamorphic rocks: marble, slate, gneiss.
• Slopes towards north and northeast.
• Tributaries of Yamuna originate here.
• Banas is only major Chambal tributary from Aravalli.
• Eastern extension: Rajmahal Hills.
• South of it lies Chotanagpur Plateau rich in minerals.

3. NORTH-EASTERN PLATEAU

• Separated by a fault between Rajmahal Hills and Meghalaya Plateau.
• Includes:
  - Meghalaya Plateau
  - Karbi Anglong Plateau
• Meghalaya Plateau divisions:
  - Garo Hills
  - Khasi Hills
  - Jaintia Hills
• Rich in minerals: coal, limestone, iron, uranium, sillimanite.
• Receives very high rainfall.
• Cherrapunji has highly eroded rocky surface.

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IV. THE INDIAN DESERT
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• Located northwest of Aravalli Range.
• Also called Marusthali.
• Rainfall: less than 150 mm.
• Features:
  - Sand dunes
  - Barchans
  - Mushroom rocks
  - Oases
• Was under sea in Mesozoic era.
• Evidence:
  - Wood fossil park at Aakal
  - Marine deposits near Jaisalmer
• Divided into:
  - Northern part sloping towards Sindh
  - Southern part sloping towards Rann of Kachchh
• Rivers:
  - Mostly ephemeral
  - Luni is the only important river
• Inland drainage creates playas and saline lakes.

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V. THE COASTAL PLAINS
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1. WESTERN COASTAL PLAINS

• Example of submerged coast.
• Narrow in middle, wider in north and south.
• Good natural harbours:
  - Kandla, Mumbai, JNPT, Marmagao, Mangalore, Cochin
• Rivers do not form deltas.
• Malabar coast has Kayals (backwaters).
• Famous boat race:
  - Nehru Trophy Vallamkali in Punnamada Kayal.

2. EASTERN COASTAL PLAINS

• Example of emergent coast.
• Broader than western plains.
• Well developed deltas:
  - Mahanadi
  - Godavari
  - Krishna
  - Kaveri
• Fewer natural ports due to deltaic coast.

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VI. THE ISLANDS
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Two major island groups:
• Andaman and Nicobar Islands (Bay of Bengal)
• Lakshadweep Islands (Arabian Sea)

1. ANDAMAN AND NICOBAR ISLANDS

• Formed due to collision of Indian Plate and Burma Minor Plate.
• Southern extension of Arakan Yoma.
• Divided into:
  - North Andaman
  - Middle Andaman
  - South Andaman
• Duncan Passage separates Little Andaman from South Andaman.
• Ten Degree Channel separates Andaman and Nicobar.
• Capital: Port Blair.
• Largest Nicobar island: Great Nicobar.
• Northernmost Nicobar: Car Nicobar.
• Made of tertiary sandstone, limestone and shale.
• Barren and Narcondam are volcanic islands.
• Only active volcanoes in India.
• Many islands have coral reefs and dense forests.
• Mostly mountainous.

2. LAKSHADWEEP ISLANDS

• Coral islands of atoll type.
• Part of Reunion Hotspot volcanism.
• Three groups:
  - Amindivi Islands
  - Laccadive Islands
  - Minicoy Island
• Collectively called Lakshadweep.
• Located 200–500 km southwest of Kerala.
• Minicoy is the largest and southernmost.
• Very low elevation (less than 5 m).
• Flat relief, no hills or rivers.

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CONCLUSION

• Physiography of India shows great diversity.
• It controls:
  - Climate
  - Drainage
  - Agriculture
  - Settlement
  - Economic activities
• Hence, understanding physiography is fundamental for Indian Geography and OPSC preparation.
 

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Subject: Geography

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