📝 Chapter Notes & Revision

Physical Features of India

🏫 MP BoardClass 9Social Science

📐 Formula & Cheat Sheet (English)

Quick Revision Notes: Class 9 Social Science (Geography)

Chapter: Physical Features of India (भारत के भौतिक स्वरूप)

### 1. Introduction & Geological Formation

  • Plate Tectonic Theory (प्लेट विवर्तनिक सिद्धांत): According to this theory, the crust (upper part) of the earth has been formed out of seven major and some minor plates.
  • Movement of Plates: The movement of the plates results in building up of stresses within the plates and the continental rocks above, leading to folding, faulting, and volcanic activity.
  • Types of Plate Boundaries:
    1. Convergent Boundary (अभिसारी सीमा): When plates come towards each other and form collisions or one slides under the other.
    2. Divergent Boundary (अपसारी सीमा): When plates move away from each other.
    3. Transform Boundary (रूपांतरित सीमा): When plates move horizontally past each other.
  • Gondwana Land (गोंडवाना भूमि): The southern part of the ancient supercontinent Pangea, consisting of India, Australia, South Africa, South America, and Antarctica. The peninsular part of India was a part of Gondwana land.
  • Angara Land: The northern part of Pangea (Laurasia).

### 2. Major Physiographic Divisions of India

India’s landmass displays great physical variations. Geologically, the Peninsular plateau constitutes one of the ancient landmasses on the earth's surface. The Himalayas and the Northern Plains are the most recent landforms.

The physical features of India are grouped under the following six major physiographic divisions:

  1. The Himalayan Mountains (हिमालय पर्वत श्रृंखला)
  2. The Northern Plains (उत्तरी मैदान)
  3. The Peninsular Plateau (प्रायद्वीपीय पठार)
  4. The Indian Desert (भारतीय मरुस्थल)
  5. The Coastal Plains (तटीय मैदान)
  6. The Islands (द्वीप समूह)

### 3. Detailed Breakdown of Divisions

I. The Himalayan Mountains

  • Location: Stretch along the northern borders of India. These are geologically young and structurally fold mountains.
  • Orientation: Run in a west-east direction from the Indus to the Brahmaputra.
  • Longitudinal Ranges:
    1. Greater Himalayas / Himadri (हिमाद्री): The northernmost range, most continuous, average height of 6,000 meters, contains all prominent peaks (e.g., Mount Everest, Kanchenjunga). Composed of granite.
    2. Lesser Himalayas / Himachal (हिमाचल): Lies south of Himadri. Altitude varies between 3,700 and 4,500 m. Famous ranges: Pir Panjal, Dhauladhar, and Mahabharat. Famous hill stations: Kullu, Kangra, Darjeeling, Nainital.
    3. Shiwaliks (शिवालिक): The outermost range of the Himalayas. Altitude: 900 to 1100 m. Composed of unconsolidated sediments (gravel and alluvium). Longitudinal valleys lying between lesser Himalayas and Shiwaliks are called Duns (e.g., Dehra Dun, Kotli Dun, Patli Dun).
  • Regional Divisions (from West to East):
    • Punjab Himalayas: Between Indus and Satluj. (Also locally known as Kashmir and Himachal Himalaya).
    • Kumaon Himalayas: Between Satluj and Kali rivers.
    • Nepal Himalayas: Between Kali and Teesta rivers.
    • Assam Himalayas: Between Teesta and Dihang rivers.
    • Purvachal: Beyond the Dihang gorge, the Himalayas bend sharply southwards along the eastern boundary of India (e.g., Patkai hills, Naga hills, Manipur hills, Mizo hills).

II. The Northern Plains

  • Formation: Formed by the interplay of three major river systems – the Indus, the Ganga, and the Brahmaputra along with their tributaries.
  • Soil Type: Alluvial soil (उपजाऊ जलोढ़ मिट्टी), highly fertile, ideal for agriculture.
  • Extent: Area of about 7 lakh sq. km, length 2400 km, breadth 240 to 320 km.
  • Relief Features (Regional divisions from north to south):
    1. Bhabar (भाबर): A narrow belt (8-16 km) parallel to the slopes of Shiwaliks where rivers deposit heavy pebbles. Streams disappear underground here.
    2. Terai (तराई): Wet, swampy, and marshy region south of Bhabar, full of wildlife and dense forests.
    3. Bangar (बांगर): The largest part of the northern plain, formed of older alluvium. Lies above the flood plains of the rivers and presents a terrace-like feature. Contains calcareous deposits locally known as Kankar.
    4. Khadar (खादर): The newer and younger deposits of the flood plains. Renewed almost every year, hence very fertile for intensive agriculture.

III. The Peninsular Plateau

  • Formation: Tableland composed of the old crystalline, igneous, and metamorphic rocks. Formed due to the breaking and drifting of the Gondwana land.
  • Broad Divisions:
    1. Central Highlands (केंद्रीय उच्च भूमि): Lies north of the Narmada river, covering a major area of the Malwa plateau. Bounded by the Vindhyas to the south and Aravalis to the northwest. Rivers flow southwest to northeast (Chambal, Sindh, Betwa, Ken).
    2. Deccan Plateau (दक्कन का पठार): A triangular landmass that lies to the south of the Narmada river. Flanked by the Western Ghats in the west and the Eastern Ghats in the east.
  • Key Comparisons:
    • Western Ghats: Higher (average height 900-1600 m), continuous, source of major rivers like Godavari, Krishna, Kaveri. Peaks: Anai Mudi, Doda Betta.
    • Eastern Ghats: Discontinuous, irregular, lower in height (average 600 m), dissected by rivers draining into the Bay of Bengal. Highest peak: Mahendragiri.

IV. The Indian Desert

  • Location: Towards the western margins of the Aravali Hills.
  • Characteristics: An undulating sandy plain covered with sand dunes (barchans - crescent-shaped dunes).
  • Climate & Vegetation: Very low rainfall (below 150 mm per year), arid climate with low vegetation cover. Streams appear during the rainy season disappear soon after.
  • Important River: Luni is the only large river in this region.

V. The Coastal Plains

  • Location: Narrow strips of plain land flanking the Peninsular plateau, bound by the Arabian Sea (West) and Bay of Bengal (East).
  • Western Coastal Plain:
    • Sandwiched between the Western Ghats and the Arabian Sea.
    • Narrow plain consisting of three sections:
      • Northern part: Konkan (Mumbai - Goa)
      • Central stretch: Kannad Plain
      • Southern stretch: Malabar Coast
  • Eastern Coastal Plain:
    • Wider and level plain along the Bay of Bengal.
    • Northern part is referred to as the Northern Circar, while the southern part is known as the Coromandel Coast.
    • Large rivers (Mahanadi, Godavari, Krishna, Kaveri) have formed extensive deltas here (e.g., Chilika Lake is an important feature here).

VI. The Islands

  • Lakshadweep Islands:
    • Close to the Malabar coast of Kerala.
    • Composed of small coral islands (earlier known as Laccadive, Minicoy, and Amindive).
    • Total area: 32 sq km. Kavaratti island is the administrative headquarters. Pitti island is uninhabited and has a bird sanctuary.
  • Andaman and Nicobar Islands:
    • An elongated chain of islands located in the Bay of Bengal extending from north to south.
    • Divided into two broad categories: Andaman in the north and Nicobar in the south.
    • These islands are elevated submarine mountains.
    • India’s only active volcano is found on Barren Island in Andaman and Nicobar group.

### Quick Memory Map for Exams

  • Highest Peak in India: K2 (Godwin-Austen) - 8,611 m (in PoK) / Kangunchunga (in Sikkim, India).
  • Youngest Fold Mountains: Himalayas.
  • Oldest Landmass: Peninsular Plateau (Gondwana land).
  • Only Active Volcano in India: Barren Island (Andaman & Nicobar).
  • Largest Saltwater Lake in India: Chilika Lake (Odisha).