class 11 notes

Class 11 Geography Notes Chapter 2 (Structure and physiography) – Geographia me Amli Kamm (Urdu) Book

Philoid

Philoid

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Geographia me Amli Kamm (Urdu)
Detailed Notes with MCQs of Chapter 2: Structure and Physiography of India. This is a crucial chapter for understanding the physical landscape of our country and frequently appears in government exams. Pay close attention to the details.

Chapter 2: Structure and Physiography - Detailed Notes

I. Introduction

  • India possesses remarkable physical diversity, ranging from lofty mountains and vast plains to ancient plateaus and extensive coastlines.
  • This diversity is a result of its unique geological history and ongoing geomorphological processes.
  • Based on geological structure and formations, India can be broadly divided into three geological divisions:
    1. The Peninsular Block
    2. The Himalayas and other Peninsular Mountains
    3. Indo-Ganga-Brahmaputra Plain

II. Geological Divisions

  1. The Peninsular Block:

    • Formation: Part of the ancient Gondwana landmass. It's been a rigid and stable block since the Cambrian period.
    • Composition: Primarily composed of ancient crystalline, igneous, and metamorphic rocks (like gneiss and schists).
    • Features:
      • Represents an old, eroded land surface characterized by broad, shallow valleys and rounded hills.
      • Experienced block faulting and vertical movements, creating rift valleys (e.g., Narmada and Tapi rivers flow through these).
      • Includes residual mountains like the Aravallis, Nallamala hills, Javadi hills, Velikonda hills, Palkonda range, and Mahendragiri hills.
      • The eastern part comprises the Chotanagpur plateau, while the west includes the Thar desert and the Deccan Trap (formed by volcanic eruptions).
      • The Karbi Anglong and Meghalaya Plateau in the northeast are extensions of the Peninsular Block, separated by the Malda fault.

  2. The Himalayas and other Extra-Peninsular Mountains:

    • Formation: Geologically young, weak, and flexible structures formed by the collision of the Indian Plate with the Eurasian Plate during the Tertiary period.
    • Features:
      • Characterized by high peaks, deep valleys, fast-flowing rivers, and U-shaped valleys carved by glaciers.
      • Tectonically active zone, prone to earthquakes, faulting, folding, and thrust plains.
      • These mountains are still rising in height.

  3. Indo-Ganga-Brahmaputra Plain:

    • Formation: A geological depression or 'foredeep' formed between the rising Himalayas in the north and the stable Peninsular Block in the south.
    • Features:
      • Filled with thick alluvial deposits (sediments) brought down by the Indus, Ganga, Brahmaputra rivers and their tributaries.
      • Average depth of alluvial deposits ranges from 1,000 to 2,000 meters.
      • It is a vast, flat, fertile plain, crucial for agriculture.

III. Physiographic Divisions of India

Based on macro variations, India is divided into the following physiographic divisions:

  1. The Northern and North-eastern Mountains (The Himalayas):

    • Extent: Stretch across northern India from Jammu & Kashmir in the west to Arunachal Pradesh in the east.
    • Orientation: West-east direction between the Indus and Brahmaputra rivers. Northwest-southeast in the northwest; Southwest-northeast in Darjeeling/Sikkim; North-south in Arunachal and Purvanchal.
    • Longitudinal Divisions (South to North):
      • Shiwaliks (Outer Himalayas): Lowest range (900-1100m altitude), discontinuous, composed of unconsolidated sediments, prone to erosion. Known for 'Duns' (longitudinal valleys) like Dehradun, Kotli Dun, Patli Dun.
      • Himachal (Lesser Himalayas): Middle range (3700-4500m altitude), rugged topography. Important ranges include Pir Panjal (longest), Dhaula Dhar, Mahabharat. Famous valleys like Kashmir, Kangra, Kullu are located here. Known for hill stations (Shimla, Mussoorie, Nainital).
      • Himadri (Greater Himalayas): Northernmost range, highest and most continuous (average altitude 6000m). Contains the world's highest peaks (Everest, Kanchenjunga, Nanga Parbat, Nanda Devi). Core composed of granite. Perennially snow-bound, source of major glaciers (Gangotri, Yamunotri).
    • Regional Divisions (West to East):
      • Punjab/Kashmir/Himachal Himalayas: Between Indus and Satluj rivers. Features Karewas (glacial clay deposits) in Kashmir, famous for saffron cultivation. Zoji La pass.
      • Kumaon Himalayas: Between Satluj and Kali rivers. Nanda Devi is the highest peak. Important glaciers and lakes found here.
      • Nepal Himalayas: Between Kali and Tista rivers. Tallest section, includes Mt. Everest, Kanchenjunga (partly), Makalu, Dhaulagiri.
      • Assam Himalayas: Between Tista and Dihang (Brahmaputra) rivers. Lower height but significant peaks like Namcha Barwa.
    • The Eastern Hills (Purvanchal): Extension of Himalayas beyond the Dihang gorge, running north-south along India's eastern boundary. Composed of sandstone (sedimentary rocks). Covered with dense forests. Includes Patkai hills, Naga hills, Manipur hills, Mizo (Lushai) hills.

  2. The Northern Plain:

    • Formation: Formed by the interplay of three major river systems – the Indus, the Ganga, and the Brahmaputra, along with their tributaries. Composed of alluvial soil.
    • Extent: Spreads over an area of 7 lakh sq. km. About 2400 km long and 240-320 km broad.
    • Divisions based on Relief (North to South):
      • Bhabar: Narrow belt (8-16 km wide) parallel to Shiwalik foothills. Composed of pebbles and boulders deposited by rivers descending from mountains. Streams disappear in this zone. Not suitable for agriculture.
      • Terai: South of Bhabar, wider belt (15-30 km). Streams re-emerge here, creating a wet, swampy, marshy region. Thickly forested, rich wildlife. Now largely reclaimed for agriculture.
      • Bhangar: Largest part of the northern plain, formed of older alluvium. Lies above flood levels, presents a terrace-like feature. Soil contains calcareous concretions (Kankar). Less fertile than Khadar.
      • Khadar: Newer, younger deposits of the floodplains. Renewed almost every year, hence very fertile. Ideal for intensive agriculture.
    • Regional Divisions (West to East):
      • Punjab Plains: Formed by the Indus and its tributaries (Jhelum, Chenab, Ravi, Beas, Satluj). Dominated by 'doabs' (land between two rivers).
      • Ganga Plains: Extends between Ghaggar and Teesta rivers. Covers Haryana, Delhi, UP, Bihar, parts of Jharkhand and West Bengal.
      • Brahmaputra Plains: Lies mainly in Assam. Formed by the Brahmaputra river. Known for riverine islands (e.g., Majuli) and frequent floods.

  3. The Peninsular Plateau:

    • Formation: Oldest landmass, part of Gondwanaland. A tableland composed of old crystalline, igneous, and metamorphic rocks. Formed due to the breaking and drifting of the Gondwana land.
    • Features: Broad and shallow valleys, rounded hills. Stable land block. Rich in mineral resources.
    • Major Divisions:
      • The Central Highlands: North of the Narmada river. Bounded by Aravallis (NW), Vindhyan range (S). Includes Malwa Plateau (drained by Chambal, Sind, Betwa, Ken), Bundelkhand, Baghelkhand, and Chotanagpur Plateau (rich in minerals like coal, iron ore, mica). Eastward extension marked by Rajmahal hills.
      • The Deccan Plateau: Triangular landmass south of the Narmada river. Bounded by Satpura range (N), Western Ghats (W), and Eastern Ghats (E). Higher in the west, slopes gently eastwards. Includes the Deccan Trap (black soil area of volcanic origin).
    • Ghats:
      • Western Ghats (Sahyadri): Parallel to the western coast. Continuous, higher elevation (900-1600m), crossed only by passes (Thal, Bhor, Pal Ghats). Orographic rainfall source. Highest peaks: Anai Mudi (2695m) in Anaimalai hills, Doda Betta (2637m) in Nilgiri hills.
      • Eastern Ghats: Parallel to the eastern coast. Discontinuous, lower elevation (average 600m), eroded by rivers (Mahanadi, Godavari, Krishna, Kaveri). Highest peak: Mahendragiri (1501m), though some sources cite Jindhagada Peak as higher. Nilgiris join Western and Eastern Ghats.

  4. The Indian Desert (Thar Desert):

    • Location: Lies to the west of the Aravalli Hills in Rajasthan.
    • Features: Undulating sandy plain covered with sand dunes (especially Barchans - crescent-shaped dunes). Arid climate with very low rainfall (below 150 mm per year). Sparse vegetation cover (xerophytic). Luni is the only significant river, often ephemeral and drains into the Rann of Kutch (inland drainage). Contains several salt lakes (e.g., Sambhar). Evidence suggests it was under the sea during the Mesozoic era.

  5. The Coastal Plains:

    • Extent: Flank the Peninsular Plateau on the west and east.
    • Western Coastal Plain: Between Western Ghats and Arabian Sea. Narrow plain. Submerged coastal plain (evidence: Dwarka). Suitable for ports and harbours (Kandla, Mumbai, Marmagao, Kochi). Divided into:
      • Gujarat Coast (Kachchh and Kathiawar coast)
      • Konkan Coast (Maharashtra, Goa)
      • Kannad Plain (Karnataka)
      • Malabar Coast (Kerala) - known for lagoons ('Kayals' e.g., Vembanad lake).
    • Eastern Coastal Plain: Between Eastern Ghats and Bay of Bengal. Wider and leveler plain. Emergent coast. Well-developed deltas formed by Mahanadi, Godavari, Krishna, Kaveri rivers. Less natural harbours. Chilika Lake (largest saltwater lake in India) is an important feature. Divided into:
      • Northern Circar (North part)
      • Coromandel Coast (South part)

  6. The Islands:

    • Lakshadweep Islands:
      • Location: Arabian Sea, close to Malabar coast.
      • Formation: Group of small coral islands (atolls). Earlier known as Laccadive, Minicoy, Amindivi.
      • Features: Total 36 islands. Kavaratti is the administrative headquarters. Pitti island has a bird sanctuary (uninhabited). Rich marine biodiversity.
    • Andaman and Nicobar Islands:
      • Location: Bay of Bengal. Bigger in size, more numerous and scattered.
      • Formation: Believed to be an elevated portion of a submarine mountain range (Arakan Yoma extension). Some volcanic origin (Barren Island is India's only active volcano).
      • Features: Divided into Andaman (North) and Nicobar (South). Port Blair is the capital. High biodiversity. Strategic importance. Saddle Peak (North Andaman) is the highest peak. Indira Point (southernmost point of India) is in the Nicobar islands (submerged partially in 2004 tsunami).

IV. Significance of India's Physiography

  • Mountains: Source of rivers, forests, minerals; influence climate (monsoon); natural barrier; tourism.
  • Plains: Fertile land for agriculture; support high population density; base for civilization.
  • Plateau: Storehouse of minerals; source of rivers; black soil for cotton; forests.
  • Coasts & Islands: Provide sites for fishing, port activities; influence climate; tourism; strategic importance.
  • Desert: Unique ecosystem; source of minerals like gypsum, salt.

Multiple Choice Questions (MCQs)

  1. The oldest landmass of the Indian subcontinent is:
    (a) The Himalayas
    (b) The Northern Plains
    (c) The Peninsular Plateau
    (d) The Coastal Plains

  2. Which of the following represents the correct sequence of the Himalayan ranges from South to North?
    (a) Himadri, Himachal, Shiwaliks
    (b) Shiwaliks, Himadri, Himachal
    (c) Shiwaliks, Himachal, Himadri
    (d) Himachal, Shiwaliks, Himadri

  3. 'Karewas' formations, known for saffron cultivation, are found in:
    (a) Kumaon Himalayas
    (b) Assam Himalayas
    (c) Kashmir Himalayas
    (d) Nepal Himalayas

  4. The Malda fault separates:
    (a) Chotanagpur Plateau from the Deccan Plateau
    (b) Meghalaya Plateau from the Peninsular Plateau
    (c) Himalayas from the Northern Plains
    (d) Western Ghats from the Eastern Ghats

  5. Which physiographic division of India is characterized by Bhabar, Terai, Bhangar, and Khadar?
    (a) The Peninsular Plateau
    (b) The Northern Plains
    (c) The Coastal Plains
    (d) The Indian Desert

  6. Anai Mudi, the highest peak of Peninsular India, is located in the:
    (a) Nilgiri Hills
    (b) Cardamom Hills
    (c) Anaimalai Hills
    (d) Palani Hills

  7. Which one of the following is NOT a feature of the Western Coastal Plains?
    (a) Narrow belt
    (b) Submerged coast
    (c) Formation of large deltas
    (d) Suitable for natural harbours

  8. The Luni river, characterized by inland drainage, flows through which physiographic division?
    (a) The Northern Plains
    (b) The Peninsular Plateau
    (c) The Indian Desert
    (d) The Coastal Plains

  9. Barren Island, the only active volcano in India, is situated in:
    (a) Lakshadweep Islands
    (b) Andaman and Nicobar Islands
    (c) Near the Malabar Coast
    (d) Near the Coromandel Coast

  10. The longitudinal valleys lying between the Lesser Himalayas (Himachal) and the Shiwaliks are known as:
    (a) Doabs
    (b) Duns
    (c) Kayals
    (d) Bhabar

Answers to MCQs:

  1. (c) The Peninsular Plateau
  2. (c) Shiwaliks, Himachal, Himadri
  3. (c) Kashmir Himalayas
  4. (b) Meghalaya Plateau from the Peninsular Plateau
  5. (b) The Northern Plains
  6. (c) Anaimalai Hills
  7. (c) Formation of large deltas (This is a feature of Eastern Coastal Plains)
  8. (c) The Indian Desert
  9. (b) Andaman and Nicobar Islands
  10. (b) Duns

Study these notes carefully. Understand the formation, location, and key features of each division. This will build a strong foundation for your geography preparation. Let me know if any part needs further clarification.

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