physical features Summary & Study Notes

What this topic is about 🌍

• Physical features of India = the main natural landforms and regions that make up the country’s surface.
• These features include mountains, plains, plateaus, deserts, coastal plains and islands that differ in origin, relief, soil and usefulness.
• Understanding them explains why India has different climates, soils, rivers and resources in different places.

Basic building blocks — smallest concepts first 🧱

• Landform: a natural shape on Earth’s surface (hill, mountain, plain, plateau, valley).
• Rock types that form landforms:
  • Igneous = formed from cooled molten rock (solid, often old and hard).
  • Metamorphic = igneous or sedimentary rocks changed by heat/pressure.
  • Sedimentary = formed by deposition of material (e.g., alluvium).
• Processes that shape landforms:
  • Tectonic uplift/folding → mountains (young folded ranges have sharp relief).
  • Erosion & weathering → rounded hills, soil formation.
  • Deposition (by rivers/sea) → plains, deltas, islands (coral vs. volcanic).

Major physiographic divisions of India — overview ✅

• India’s physical features are commonly grouped into six main divisions:
  • Himalayan Mountains — northern folded mountains.
  • Northern Plains — large alluvial plains formed by rivers.
  • Peninsular Plateau — old, stable tableland of igneous/metamorphic rocks.
  • Indian Desert — arid sandy region in the west.
  • Coastal Plains — narrow western and wide eastern coastal strips.
  • Island groups — Lakshadweep (coral) and Andaman & Nicobar (volcanic/continental).

The Himalayan Mountains — from basics to details 🏔️

• What they are: a young, folded mountain system along India’s northern border formed by collision of tectonic plates.
• Key features:
  • Runs west → east from the Indus to the Brahmaputra, ~2400 km long and 150–400 km wide.
  • Very high peaks, deep valleys, active uplift and many glaciers (youthful topography).
• Longitudinal (north–south) zonation (from north to south):
  1. Inner/Great Himalaya (Himadri)
     • Highest and most continuous; average ~6,000 m; contains major peaks and glaciers.
     • Core rock: granite; perennial snow.
     • Important: many highest Himalayan peaks (table below).
  2. Lesser Himalaya (Himachal)
     • Rugged, altitudes 3,700–4,500 m; compressed/altered rocks.
     • Contains important valleys (Kangra, Kullu) and hill stations.
  3. Shiwaliks (Outer Himalaya)
     • Lowest, 900–1,100 m; composed of unconsolidated sediments (gravel/alluvium).
     • Longitudinal valleys between Shiwaliks and lesser Himalaya called duns (e.g., Dehra Dun).
• East–west regional divisions (by river gaps):
  • Punjab/Kashmir/Himachal Himalaya (west), Kumaon (between Satluj–Kali), Nepal Himalaya, Assam Himalaya, then Purvachal (Eastern hills) in the northeast (Patkai, Naga, Manipur, Mizo hills).
• Table — some highest peaks (country and height)
  • Mt. Everest (Nepal) — 8,848 m
  • Kanchenjunga (India/Nepal) — 8,598 m
  • Makalu (Nepal) — 8,481 m
  • Dhaulagiri (Nepal) — 8,172 m
  • Nanga Parbat (India/Pakistan region) — 8,126 m
  • Annapurna (Nepal) — 8,078 m
  • Nanda Devi (India) — 7,817 m
  • Kamet (India) — 7,756 m

The Northern Plains — how they formed and their parts 🏞️

• How formed: millions of years of river deposition (alluvium) from the Indus, Ganga and Brahmaputra and their tributaries at the Himalayan foothills.
• Size and significance:
  • Area ~7 lakh sq km; ~2,400 km long and 240–320 km wide; very fertile and densely populated; major agricultural region.
• Major sub-regions (west → east):
  • Punjab Plains — formed by the Indus system (doabs = land between two rivers).
  • Ganga Plain — between Ghaggar and Teesta (Haryana, Delhi, UP, Bihar, parts of Jharkhand and West Bengal).
  • Brahmaputra Plain — in Assam (eastmost).
• Relief zones inside the plains (from Himalaya southwards):
  1. Bhabar — narrow belt (8–16 km) of coarse pebbles at foot of Shiwaliks; streams disappear here.
  2. Terai — south of bhabar; wet, marshy, forested (became agricultural in places).
  3. Bhangar — older alluvium above floodplains, terrace-like; soil has calcareous deposits called kankar.
  4. Khadar — newer alluvium of floodplains, annually renewed, very fertile.
• River behavior:
  • Rivers deposit silt, form distributaries in lower courses; form riverine islands (Majuli in Brahmaputra — world’s largest inhabited river island).

The Peninsular Plateau — old tableland and its parts 🏔️

• Origin: part of ancient Gondwana; made of old igneous and metamorphic rocks (stable landmass).
• Shape: roughly triangular, higher in the west and sloping east.
• Two broad parts:
  1. Central Highlands (north of Narmada)
     • Includes Malwa plateau; bounded by Aravalis (NW), Vindhyas and Satpura; rivers Chambal, Sind, Betwa, Ken flow SW → NE.
     • Eastwards extend as Bundelkhand, Baghelkhand; Chotanagpur plateau lies to the east drained by Damodar.
  2. Deccan Plateau (south of Narmada)
     • Triangular, flanked by Western Ghats (west) and Eastern Ghats (east).
     • Higher in west; includes extensions like Meghalaya & North Cachar hills.
• Ghats:
  • Western Ghats — continuous, higher (900–1,600 m average), cause orographic rainfall on western slopes, passes: Thal, Bhor, Pal.
  • Eastern Ghats — discontinuous, lower (~600 m), dissected by rivers, irregular.
• Soils & rocks:
  • Deccan Trap (volcanic) → black soil (important for cotton).

The Indian Desert — basics 🏜️

• Location: western margin of Aravalis, mainly in Rajasthan.
• Features:
  • Undulating sandy plain with sand dunes (barchans = crescent-shaped dunes).
  • Very low rainfall (<150 mm/year), sparse vegetation; streams are seasonal and disappear in sand.
  • Luni is the principal river.

The Coastal Plains — west & east differences 🏖️

• Western coastal plain:
  • Narrow strip between Western Ghats and Arabian Sea; sections: Konkan (north), Kannad (central), Malabar (south).
• Eastern coastal plain:
  • Wider and level; northern part called Northern Circar, southern part called Coromandel Coast.
  • Large rivers (Mahanadi, Godavari, Krishna, Kaveri) form extensive deltas.
  • Chilika Lake (Odisha) is India’s largest salt water lake.

The Islands — two groups and their origins 🏝️

• Lakshadweep:
  • Off Malabar coast; coral islands (coral origin), small area (~32 sq km), Kavaratti = HQ.
• Andaman & Nicobar:
  • In Bay of Bengal; larger, numerous, divided into Andaman (north) and Nicobar (south).
  • Partly volcanic (Barren Island is India’s only active volcano); thick forests, equatorial climate.
• Corals:
  • Coral polyps build reefs in warm, shallow, mud-free waters → fringing reefs, barrier reefs, atolls.

Why these regions matter — short summary 🔎

• Mountains = water sources (glaciers), forest wealth.
• Northern plains = agricultural heartland, early civilizations.
• Plateau = mineral-rich, important for industry.
• Coasts & islands = fishing, ports, strategic locations.

Exercises — solved step-by-step 📝

1. Multiple choice — choose right answer

• (i) A landmass bounded by sea on three sides = Peninsula.
  • Answer: (c) Peninsula.
  • Reason: “Bounded by sea on three sides” = definition of peninsula.
• (ii) Mountain ranges in eastern India forming boundary with Myanmar = Purvachal.
  • Answer: (c) Purvachal.
  • Reason: Purvachal = Eastern hills (Patkai, Naga, Manipur, Mizo hills).
• (iii) Western coastal strip south of Goa = Malabar Coast.
  • Answer: Malabar Coast (southern stretch).
  • Note: If options printed incorrectly, the correct name is Malabar.
• (iv) Highest peak in the Eastern Ghats = Mahendragiri.
  • Answer: (c) Mahendragiri.

2. Short answer questions — stepwise

• (i) What is the bhabar? Solution:
  1. Bhabar is a narrow belt (8–16 km) at the foot of the Shiwaliks.
  2. It consists of coarse pebbles deposited by streams; many streams disappear into this porous layer.
• (ii) Name the three major divisions of the Himalayas from north to south. Solution:
  1. Inner/Great Himalaya (Himadri) — northernmost, highest peaks.
  2. Lesser Himalaya (Himachal) — middle rugged ranges.
  3. Shiwaliks (Outer Himalaya) — southernmost, lower hills of unconsolidated sediments.
• (iii) Which plateau lies between the Aravali and the Vindhyan ranges? Solution:
  1. The Malwa Plateau (part of the Central Highlands) lies between Aravali (NW) and Vindhyan ranges.
• (iv) Name the island group of India having coral origin. Solution:
  1. Lakshadweep islands — coral origin.

3. Distinguish between — brief points

• (i) Bhangar vs Khadar
  • Bhangar:
    • Older alluvium, lies above floodplain, terrace-like, contains kankar (calcareous nodules).
  • Khadar:
    • Newer alluvium, forms floodplains, renewed by floods, very fertile.
• (ii) Western Ghats vs Eastern Ghats
  • Western Ghats:
    • Continuous, higher (900–1,600 m), produce orographic rainfall, runs parallel to west coast.
  • Eastern Ghats:
    • Discontinuous, lower (~600 m), dissected by rivers, irregular ranges along east coast.

4. Major physiographic divisions; contrast Himalayas vs Peninsular Plateau

• Major divisions: Himalayas, Northern Plains, Peninsular Plateau, Indian Desert, Coastal Plains, Islands.
• Contrast — Himalayas vs Peninsular Plateau:
  • Himalayas:
    • Young folded mountains, very high peaks, sharp relief, active tectonics, many glaciers, deep valleys.
  • Peninsular Plateau:
    • Old, stable tableland, rounded hills and broad shallow valleys, igneous/metamorphic rocks, mineral-rich.

5. Account of the Northern Plains of India (concise)

• Formed by deposition of alluvium from Indus, Ganga and Brahmaputra systems.
• Area ~7 lakh sq km; fertile, densely populated, major agricultural zone.
• Divisions: Punjab (Indus), Ganga, Brahmaputra plains; internal zones: bhabar, terai, bhangar, khadar.
• Features: doabs (land between rivers), distributaries, riverine islands (Majuli).

6. Short notes

• (i) The Indian Desert:
  • Located in western India (Rajasthan), sandy undulating plain with dunes, very low rainfall (<150 mm), Luni river, sparse vegetation and seasonal streams.
• (ii) The Central Highlands:
  • North of Narmada, includes Malwa plateau; bounded by Vindhyas and Satpura; drained by rivers Chambal, Betwa, Ken; slopes northeastward; includes Bundelkhand and Baghelkhand regions.
• (iii) The Island groups of India:
  • Lakshadweep = coral islands near Kerala; Andaman & Nicobar = larger volcanic/continental islands in Bay of Bengal; Barren Island is active volcano; both groups rich in flora/fauna and strategic importance.

Map skills — how to mark key features (practical tips) 🗺️

• Mountain & hill ranges to mark:
  • Karakoram, Zaskar — mark in northern Jammu & Kashmir (Karakoram NW of main Himalaya).
  • Patkai Bum, Jaintia — mark in NE India along Myanmar border.
  • Vindhya, Aravali, Cardamom hills — mark central India (Vindhya across MP), Aravalis from Gujarat → Delhi, Cardamom in southern TN/Kerala.
• Peaks to locate:
  • K2 — northernmost Karakoram (on India-Pakistan/China region).
  • Kanchenjunga — NE Sikkim.
  • Nanga Parbat — far NW (Pakistan region).
  • Anai Mudi — southern tip of Western Ghats (Kerala).
• Plateaus: Chotanagpur (Jharkhand region), Malwa (western MP/eastern Rajasthan).
• Other: Indian Desert (western Rajasthan), Western Ghats (west coast strip), Lakshadweep (small islands off Kerala).

Project / activity — how to solve the hidden-features puzzle 🔍

• Strategy:
  1. List likely names hidden (peaks, passes, ranges, plateaus, hills, duns) from your textbook or atlas.
  2. Scan the puzzle horizontally, vertically, diagonally for the first letter of each target name.
  3. Cross out found names and mark their approximate location on a blank physical map of India.
  4. For each found feature, write a 1-line description (where and why it’s important).

Tip: Use an atlas while studying — visual location on maps cements the links between names, relief and real places.