Indian Geography

THE HIMALAYAS

• Meaning: “Abode of Snow”.
• Characteristics: Youngest fold mountains; mainly sedimentary rocks.
• Extent: From Indus River (west) to Brahmaputra River (east).
• Eastern Himalayas (Purvanchal): Patkai Hills, Naga Hills, Mizo Hills, Garo Hills, Khasi Hills, Jaintia Hills.
• Pamir Knot: Called the “Roof of the World”; connects Himalayas with Central Asian ranges.

THREE PARALLEL ZONES

Great Himalayas (Himadri)

• Average elevation: ~6,000 m
• Important Passes (above 4,500 m):
  • Himachal Pradesh: Shipki La, Bara Lapcha La
  • Jammu & Kashmir / Ladakh: Burzil, Zoji La
  • Uttarakhand: Niti, Lipulekh, Thang La
  • Sikkim: Jelep La, Nathu La
• Major Peaks:
  • Mt. Everest – 8,848 m (Nepal)
  • Mt. Kanchenjunga – 8,598 m (India–Nepal border)
  • Mt. Makalu – 8,481 m
  • Mt. Dhaulagiri – 8,172 m
  • Mt. Nanga Parbat – 8,126 m
  • Mt. Annapurna – 8,078 m
  • Mt. Nanda Devi – 7,817 m (India)

Lesser Himalayas (Himachal)

• Average height: 3,700 – 4,500 m
• Relief: Peaks up to 5,000 m; valleys down to ~1,000 m
• Important ranges: Dhauladhar, Pir Panjal, Nag Tibba, Mussoorie Range

Outer Himalayas (Shiwaliks)

• Lowest range: 900 – 1,200 m
• Location: Foothills between Lesser Himalayas and Northern Plains

TRANS-HIMALAYAN ZONE

• Location: North of the Great Himalayas
• Main ranges: Karakoram, Ladakh, Zanskar
• Highest Peak: K2 (Godwin Austin) – 8,611 m
• Other Peaks: Hidden Peak, Broad Peak, Gasherbrum II
• Major Glaciers:
  • Siachen – >72 km (longest outside polar regions)
  • Biafo, Baltoro, Batura, Hispar
• Feature: Largest snowfield outside Polar Regions

INTRODUCTION

• Location: South of the Himalayas and north of the Peninsular Plateau.
• Formation: Depositional work of three river systems – Indus, Ganga, Brahmaputra.
• Soil Type: Alluvial.
• Westernmost Portion: Occupied by the Thar Desert.
• Alluvium Thickness: Maximum in Ganga plains; minimum in Western Plains.

FOUR DIVISIONS OF THE NORTHERN PLAINS (North → South)

DELTA PLAINS

• Extension of Khadar land.
• Composition: Old mud, new mud, marsh.
• Upland Areas: Called Chars.
• Marshy Areas: Known as Bils.

Key Facts

• Alluvial plains formed by Indus–Ganga–Brahmaputra systems.
• Thar Desert lies in the western sector.
• Bhabar: Porous belt where streams vanish.
• Tarai: Wet belt where streams reappear.
• Bhanger: Old alluvium with kankar & saline crusts.
• Khadar: New, fertile floodplain deposits.
• Delta plains: Include Chars (uplands) and Bils (marshes).

INTRODUCTION

• Location: South of the Indo-Gangetic Plains.
• Shape: Triangular plateau with a broad base in the north.
• Boundaries: Flanked by seas on three sides.
• Eastern Boundary: Eastern Ghats
• Western Boundary: Western Ghats

MAJOR DIVISIONS

Dividing Line: Narmada River (flows through a rift valley)

Key Facts

• Narmada River flows in a rift valley and divides Malwa (north) & Deccan (south).
• Vindhya Plateau lies between Malwa and the Narmada zone.
• Chhota Nagpur Plateau includes the Ranchi Plateau and lies west of the Bengal Basin.
• Deccan Plateau is of volcanic (basaltic) origin — Deccan Traps.
• The plateau is bounded by the Eastern Ghats and Western Ghats.

COASTLINE

• Total Coastline: 7,516 km
• Longest Coastline (State): Gujarat
• Second Longest: Andhra Pradesh

ANDAMAN & NICOBAR ISLAND GROUP

• Total Islands: 572
• Largest Island: Middle Andaman
• Origin: Extension of the mountain system of Northeast India
• Highest Peak: Saddle Peak (737 m) — North Andaman
• Volcanic Islands:
  • Barren Island — India’s only active volcano
  • Narcondam Island — dormant volcanic island

ARABIAN SEA GROUP (LAKSHADWEEP)

• Type: Coral islands
• Reef Type: Fringing reefs
• Layout: Lakshadweep islands in the north, Minicoy in the south

IMPORTANT CHANNELS & PASSAGES

Key Facts

• India’s coastline length: 7,516 km
• Longest coastline state: Gujarat
• Andaman–Nicobar: tectonic/continental origin chain
• Lakshadweep: coral origin
• Only active volcano: Barren Island
• 10° Channel divides Andaman & Nicobar groups
• 8° Channel separates India and Maldives

1️⃣ CLASSIFICATION

2️⃣ HIMALAYAN RIVERS — The Big Three

Note: Indus, Ganga, Brahmaputra are antecedent rivers.

3️⃣ PENINSULAR RIVERS

🟢 A. East-Flowing Rivers (Delta Forming)

🔵 B. West-Flowing Rivers (Estuary Forming)

Rule: East-flowing → Delta | West-flowing → Estuary

4️⃣ MAJOR DAMS & PROJECTS

5️⃣ INTER-STATE WATER DISPUTES

Key Facts

• Largest Peninsular River → Godavari
• Longest Ganga tributary → Yamuna
• Oldest dam → Grand Anicut (Kaveri)
• Highest plunge waterfall → Jog Falls (Sharavati)
• Largest river island → Majuli
• Largest delta → Sunderban
• Longest earthen dam in Asia → Hirakud
• Rift valley rivers → Narmada, Tapi, Mahi
• Antecedent rivers → Indus, Ganga, Brahmaputra, Sutlej
• Sorrows → Bihar (Kosi), Bengal (Damodar), Odisha (Mahanadi), Assam (Brahmaputra)

INTRODUCTION

• Type: Tropical Monsoon Climate with strong regional variations.
• Major Controls: Himalayas (climatic barrier), Indian Ocean, Arabian Sea, Bay of Bengal.
• Köppen Types in India: Am, Aw, BSh, BWh, Cwa/Cwg, Dsb, E, ET etc.

FACTORS AFFECTING INDIAN CLIMATE

SEASONS IN INDIA (IMD)

DISTRIBUTION OF RAINFALL

• Highest Rainfall: Mawsynram (Meghalaya)
• Lowest Rainfall: Jaisalmer (Rajasthan)
• Rain Shadow: Lee of Western Ghats — Pune, Solapur, Madurai

CLIMATIC REGIONS (Köppen / Trewartha)

IMPORTANT METEOROLOGICAL TERMS

Key Facts

• Mawsynram — highest average rainfall in world
• Cherrapunji — record monthly/year rainfall (1899)
• Jaisalmer — driest place in India
• Drass — among coldest inhabited places
• Monsoon term introduced by Arab traders
• El Niño → drought tendency; La Niña → good monsoon
• Indian Institute of Tropical Meteorology — Pune
• IMD established — 1875

INTRODUCTION

• Soil: Upper layer of earth’s crust made of minerals, organic matter, water and air — essential for plant growth.
• Formation Factors: Parent rock, climate, topography, vegetation, time.
• Main Classification: ICAR soil classification.
• Major Soil Groups: Alluvial, Black, Red, Laterite, Arid, Saline, Peaty, Forest.

MAJOR SOIL TYPES OF INDIA (ICAR)

OTHER CLASSIFICATIONS

By Age (Alluvial)

• Khadar: New, fine, annually renewed, more fertile
• Bhanger: Old, coarse, kankar nodules, less fertile

By Origin

• Residual: Red, Black, Laterite, Desert
• Transported: Alluvial, Deltaic, Coastal

By Texture

• Sandy, Loamy, Clayey, Silty, Peaty

SOIL DEGRADATION & EROSION

SOIL HEALTH – GOVERNMENT SCHEMES

Key Facts

• Alluvial soil covers the largest area in India (~40%).
• Black soil is best suited for cotton cultivation.
• Laterite soil requires heavy manuring for fertility.
• Khadar is more fertile than Bhanger.
• Regur means cotton soil.
• Laterite word comes from Latin “later” meaning brick — used in construction.
• Red soil colour is due to ferric oxide.
• Saline soil is locally called Reh, Kallar, Usara, Thur.
• Kuttanad (Kerala) — farming below sea level (peaty soil region).
• Himalayan soils are young and highly erosion-prone.
• Wind erosion is dominant in Rajasthan and Gujarat.
• Water erosion is dominant in MP, Maharashtra, Tamil Nadu, and UP.
• Indo-Gangetic Plains show highest agricultural productivity due to alluvial soils.
• Pedology = study of soils.
• Edaphology = study of soil in relation to crops.