Physical Features of India

Introduction to India’s Physical Diversity

• India exhibits almost every major landform found on Earth: mountains, plains, plateaus, deserts, coasts and islands.

• Geologically the sub-continent merges two contrasting realms:

  • The ancient, stable Peninsular Plateau composed mainly of igneous & metamorphic rocks.

  • The comparatively young, tectonically unstable Himalayan mountain belt and the alluvium-filled Northern Plains.

• These features generate pronounced regional contrasts in relief, climate, soils, drainage and natural resources.

Major Physiographic Divisions (with typical widths/lengths)

1. The Himalayan Mountains

2. The Northern Plains

3. The Peninsular Plateau

4. The Indian Desert

5. The Coastal Plains

6. The Islands
   (Fig. 2.2 in the textbook illustrates their spatial arrangement.)

The Himalayan Mountains

• Orientation & Extent

  • Geologically young, fold-mountain arc running $\approx 2,400\ \text{ km}$ W–E from the Indus gorge to the Brahmaputra (Dihang) gorge.

  • Width tapers from $\approx 400\ \text{ km}$ in Kashmir to $\approx 150\ \text{ km}$ in Arunachal Pradesh.

• Three longitudinal (latitudinal) ranges:

  1. Himadri / Great Himalaya

  • Northernmost, most continuous, average heigh

  • $\approx 6,000\ \text{ m}$.

  • Core of granite; perennial snowfields; source of many glaciers.

  • Contains world-class peaks (see table below).

  1. Himachal / Lesser Himalaya

  • South of Himadri; highly compressed & altered rocks.

  • Altitude $3,700!\text{–}!4,500\ \text{ m}$; average width $\approx 50\ \text{ km}$.

  • Important ranges: Pir Panjal (longest), Dhaula Dhar, Mahabharat.

  • Notable valleys: Kashmir, Kangra, Kullu; hub of famous hill stations (e.g.
    Mussoorie, Nainital, Ranikhet).

  1. Shiwalik / Outer Himalaya

  • Outermost foothill zone; width $10!\text{–}!50\ \text{ km}$; altitude $900!\text{–}!1,100\ \text{ m}$.

  • Built of unconsolidated river-borne sediments; covered with gravel & alluvium.

  • Longitudinal valleys between Shiwalik & Lesser Himalaya are called duns (e.g.
    Dehra Dun, Kotli Dun, Patli Dun).

• Lateral / Regional (W–E) subdivisions, demarcated by major river gorges:

  • Indus–Satluj ⇒ Punjab Himalaya (regional names: Kashmir & Himachal Himalaya).

  • Satluj–Kali ⇒ Kumaon Himalaya.

  • Kali–Teesta ⇒ Nepal Himalaya.

  • Teesta–Dihang ⇒ Assam Himalaya.

  • E of Dihang gorge Himalaya bends southward → Purvachal / Eastern Hills (Patkai, Naga, Manipur & Mizo Hills); composed mainly of hard sandstones; parallel ranges with dense forests.

• Highest Peaks (partial list)
  

  Peak	Country	Height (m)
  Mt. Everest	Nepal	$8,848$
  Kanchenjunga	India	$8,598$
  Makalu	Nepal	$8,481$
  Dhaulagiri	Nepal	$8,172$
  Nanga Parbat	India	$8,126$
  Annapurna	Nepal	$8,078$
  Nanda Devi	India	$7,817$
  Kamet	India	$7,756$
  Namcha Barwa	India	$7,756$
  Gurla Mandhata	Nepal	$7,728$
  Significance

  • Acts as climatic barrier, source of perennial rivers, provider of hydro-electric power, harbours great biodiversity and medicinal plants, strategic frontier.

The Northern Plains

• Genesis

  • Formed by alluvium from three major river systems — Indus, Ganga, Brahmaputra — deposited over millions of years at the Himalayan foothills.

• Dimensions: length $\approx 2,400\ \text{ km}$; width $240!\text{–}!320\ \text{ km}$; area \approx 7\ \text{lakh km^2}.

• Densely populated due to fertile alluvium, adequate water & favourable climate; India’s agricultural heartland.

• Three sectoral divisions:

  1. Punjab Plain (Indus system; dominated by doabs).

  2. Ganga Plain (Ghaggar–Teesta sector; stretches across Haryana, Delhi, U.P., Bihar, Jharkhand & West Bengal).

  3. Brahmaputra Plain (Assam; houses Majuli, world’s largest inhabited riverine island).

• Micro-relief zones (N→S):

  • Bhabar: $8!\text{–}!16\ \text{ km}$ gravel belt at Shiwalik base; streams disappear.

  • Terai: marshy, re-emergent streams; reclaimed for farming; e.g.
    Dudhwa National Park.

  • Bhangar: older alluvium terrace; contains kankar (calcareous nodules).

  • Khadar: newer floodplain; renewed annually; most fertile.

• Depositional Landforms

  • Riverine islands, meanders, ox-bow lakes, distributaries in lower courses; rich wetland ecology.

The Peninsular Plateau

• Ancient crystalline tableland; remnant of Gondwana; characterised by broad, shallow valleys & rounded hills.

• Two macro divisions:

  1. Central Highlands

  • N of Narmada; includes Malwa Plateau.

  • Bounded by Aravalis (NW) & Satpura Range (S); slopes SW→NE (drainage: Chambal, Sind, Betwa, Ken).

  • Eastern spurs: Bundelkhand, Baghelkhand; further east → Chotanagpur Plateau (Damodar basin).

  1. Deccan Plateau

  • Triangular, S of Narmada; base along Satpura–Maikal–Mahadev–Kaimur.

  • Western edge higher; gentle eastward slope; fault-separated from Chotanagpur.

  • N-E extension: Meghalaya, Karbi-Anglong & N Cachar Hills (hill ranges: Garo, Khasi, Jaintia).

• Escarpments

  • Western Ghats (parallel to W coast; continuous; average height $900!\text{–}!1,600\ \text{ m}$; passes: Thal, Bhor, Pal).

  • Eastern Ghats (Mahanadi valley to Nilgiris; discontinuous, dissected; average $\approx 600\ \text{ m}$).

  • Orographic rainfall on W Ghats; rain-shadow on leeward side.

• Highest Peaks

  • Anai Mudi $2,695\ \text{ m}$ (W Ghats).

  • Doda Betta $2,637\ \text{ m}$ (Nilgiri).

  • Mahendragiri $1,501\ \text{ m}$ (E Ghats).

• Other Hills

  • Shevroy, Javadi (SE of Eastern Ghats).

• Deccan Trap

  • Layered basaltic lava province; weathering of basalt yields black cotton soils — highly fertile, moisture-retentive.

• Aravali Hills

  • Old, denuded ridge (Gujarat → Delhi); forms W & NW plateau margin.

The Indian Desert (Thar)

• Location: W of Aravali; extending up to Indo-Pak border.

• Relief: undulating sand plain studded with barchans (crescent) & longitudinal dunes (near border).

• Climate: arid; rainfall <150\ \text{ mm yr^{-1}}; sparse vegetation.

• Drainage: ephemeral streams; only significant river = Luni.

• Economic aspects: potential solar-wind energy, tourism around Jaisalmer, salt extraction.

The Coastal Plains

• Narrow strips flanking the Peninsular Plateau.

Western Coastal Plain (Arabian Sea side)

• Sandwiched between Western Ghats & sea; relatively narrow.

• Sub-sections:

  1. Konkan (Mumbai–Goa)

  2. Kannad / Karnataka Plain

  3. Malabar Coast (southern stretch; lagoons/backwaters such as Vembanad, Kayal).

Eastern Coastal Plain (Bay of Bengal side)

• Wider & more level; dissected by large river deltas.

• Northern portion: Northern Circar; southern: Coromandel Coast.

• Major delta-forming rivers: Mahanadi, Godavari, Krishna, Kaveri.

• Chilika Lake (Odisha) — largest salt-water lagoon in India.

The Islands of India

Lakshadweep (Arabian Sea)

• 32\ \text{ km^2}, coral-origin atolls & reefs; renamed in $1973$ (formerly Laccadive, Minicoy, Amindive).

• Headquarter: Kavaratti.

• Pitti Island – uninhabited bird sanctuary.

Andaman & Nicobar (Bay of Bengal)

• Chain of >$300$ islands, divided by $10^{\circ}$ N latitude into Andamans (N) & Nicobars (S).

• Believed to be emergent parts of submarine mountains; dense equatorial forests; great biological diversity.

• India’s only active volcano on Barren Island (Andamans).

• Strategic importance: surveillance of Bay of Bengal & Strait of Malacca; potential blue-water economy.

Coral Concepts

• Coral polyps: microscopic colonial organisms secreting $CaCO_3$ skeletons.

• Reef types: fringing, barrier (e.g.
  Great Barrier Reef, Australia), atoll (ring-/horse-shoe-shaped; Lakshadweep mostly atoll).

Complementarity of Physiographic Units

• Mountains: water towers & forest wealth.

• Plains: country’s granaries; cradle of ancient civilisations.

• Plateau: mineral storehouse → industrialisation driver.

• Desert: potential for solar/wind power, unique arid ecosystems.

• Coasts & Islands: fisheries, ports, tourism, strategic defense.

Key Geographical Terms & Concepts

• Doab: land between two rivers; “Punjab” literally “five waters”.

• Bhabar / Terai / Bhangar / Khadar: successive N→S belts in Northern Plains.

• Dun: longitudinal valley between Lesser Himalaya & Shiwalik.

• Passes in Western Ghats: Thal, Bhor, Pal.

• Orographic rainfall: uplift of moist winds by mountains → cooling & condensation.

Important Numerical Facts (LaTeX format)

• Himalayan arc length $\approx 2,400\ \text{ km}$; width $400!\text{–}!150\ \text{ km}$.

• Himadri average elevation $\approx 6,000\ \text{ m}$.

• Northern Plains area $\approx 7\times10^{5}\ \text{ km}^2$.

• Deccan peaks: $\text{Anai Mudi}=2,695\ \text{ m},\ \text{Doda Betta}=2,637\ \text{ m}$.

• Indian Desert rainfall <150\ \text{ mm yr}^{-1}.

Map & Field-Study Pointers

• Locate mountain / hill ranges: Karakoram, Zaskar, Patkai Bum, Jaintia, Vindhya, Aravali, Cardamom.

• Peaks: $K2\,(8,611\text{ m}),\ \text{Kanchenjunga},\ \text{Nanga Parbat},\ \text{Anai Mudi}$.

• Plateaus: Malwa, Chotanagpur.

• Western Ghats, Indian Desert, Lakshadweep Islands on outline map.

Sample Examination / Revision Prompts

• Define bhabar; list its hydrological significance.

• Enumerate three N→S Himalayan ranges; comment on lithology.

• Differentiate Bhangar vs Khadar; Western vs Eastern Ghats.

• Explain relief & resources contrast between Himalaya and Peninsular Plateau.

• Describe physiography, agriculture & population patterns of the Northern Plains.

• Short notes: Indian Desert, Central Highlands, Island groups.

These bullet-point notes recapitulate every major and subsidiary detail from the given textbook extract, expand concepts with explanations, supply numerical facts in $\LaTeX$, highlight examples/etymologies, and establish the functional inter-relationships among India’s diverse physical regions.