Indian Geography 

1. Physiography of India – Major Physiographic Divisions and Their Significance

India’s physiography can be broadly divided into six main physical divisions:

  1. The Himalayas:

    • Located in the northern part of India, the Himalayas are a young fold mountain range.

    • Significant for their role in shaping India’s climate, providing water resources, and forming the backdrop for many rivers.

  2. The Northern Plains:

    • Alluvial plains formed by the rivers Ganga, Yamuna, and their tributaries.

    • Fertile land, crucial for agriculture and densely populated.

  3. Peninsular Plateau:

    • The largest plateau region, mainly composed of ancient crystalline rocks.

    • Includes the Deccan Plateau, Chota Nagpur Plateau, and Malwa Plateau.

  4. The Coastal Plains:

    • The western and eastern coastal plains, with significant ports such as Mumbai, Chennai, and Kolkata.

  5. The Desert Region:

    • Located in the northwest (Rajasthan), primarily the Thar Desert.

  6. Islands:

    • Andaman and Nicobar Islands (Bay of Bengal) and Lakshadweep Islands (Arabian Sea), both rich in biodiversity and strategic importance.

2. Rock System in India

  • Archean (ancient, crystalline rocks, basement of the Peninsular plateau).

  • Proterozoic (shift in life forms, includes the Vindhyan and Cuddapah systems).

  • Phanerozoic (includes sedimentary rocks, also hosts the Indo-Gangetic alluvial deposits).

3. Mountain Ranges in India

  1. Himalayas:

    • North of India, the world’s youngest fold mountains.

    • Divided into three major ranges: The Greater Himalayas, The Lesser Himalayas, and the Outer Himalayas (Shivaliks).

  2. Western Ghats:

    • A mountain range running parallel to the western coast, known for its biodiversity and ecological significance.

  3. Aravalli Range:

    • One of the oldest mountain ranges, extending from Gujarat to Delhi.

4. Plateaus in India

  • Peninsular Plateau:

    • Composed mainly of granite and gneiss, it is rich in minerals and forms the backbone of the country.

  • Deccan Plateau:

    • A large plateau that forms much of southern India.

  • Chota Nagpur Plateau:

    • Rich in mineral resources, including coal, iron, and manganese.

  • Malwa Plateau:

    • Located in central India, it forms the western part of the Madhya Pradesh region.

5. Islands of India

  • Andaman and Nicobar Islands:

    • Located in the Bay of Bengal, strategically important and home to unique species.

  • Lakshadweep Islands:

    • Situated in the Arabian Sea, known for coral reefs and biodiversity.

6. Mountain Passes in India

  • Key passes like Zoji La, Bara Lacha La, Sela Pass, and Nathu La have historical and strategic significance, especially in connecting regions and defense.

7. Glaciers in India

  • Siachen Glacier (Karakoram range), Gangotri Glacier (Himalayas), and Biafo Glacier (Karakoram range) are significant both for their role in the river systems and as natural reserves of freshwater.

8. Lakes in India

  • Sambhar Lake (Rajasthan), Dal Lake (Jammu & Kashmir), Vembanad Lake (Kerala), and Loktak Lake (Manipur) are significant freshwater and saline lakes with ecological and cultural importance.

9. Natural Vegetation of India

  • Evergreen Forests: Found in the Western Ghats and the Himalayan foothills.

  • Tropical Deciduous Forests: In the central and eastern regions, including the Deccan Plateau.

  • Thorn Forests: Found in dry areas like Rajasthan and Gujarat.

  • Mangroves: Found along the coastal regions like the Sundarbans.

10. Soils of India

  • Types:

    • Alluvial Soil: Found in the northern plains and river basins, supports agriculture.

    • Black Soil: Found in the Deccan Plateau, good for cotton cultivation.

    • Red Soil: Found in areas with moderate rainfall.

    • Laterite Soil: Found in tropical areas like Kerala.

    • Desert Soil: Found in Rajasthan and parts of Gujarat.

11. Climate of India

  • Indian Monsoon:

    • Divided into southwest and northeast monsoons, influencing agriculture and weather patterns.

  • Western Disturbances:

    • Occur in the winter, bringing rainfall to the northern and western regions.

  • Temperature Variations:

    • Varies significantly from the cold Himalayas to the hot Thar desert and the humid coastal regions.

12. Drainage System of India – River Systems

  • Indus River System: Originates in Tibet, flows through Pakistan.

  • Ganga River System: Originates from the Gangotri Glacier, flowing through Northern India.

  • Brahmaputra River System: Originates in Tibet, flows through Assam.

  • Peninsular Rivers: Krishna, Godavari, Mahanadi, Kaveri, among others.

  • Interlinking of Rivers: Government projects aim to interlink major rivers for irrigation and flood control.

13. The Universe – Origin and Composition

  • Big Bang Theory: The leading explanation for the origin of the universe.

  • Solar System: Composed of the Sun, planets, and other celestial bodies.

  • Formation of Earth: Occurred around 4.5 billion years ago from the solar nebula.

14. Interior of the Earth – Sources and Structure

  • Layers:

    • Crust: Outer layer, thin and solid.

    • Mantle: Composed of semi-solid rock, convection currents drive plate tectonics.

    • Core: Consists of a liquid outer core and solid inner core.

  • Plate Tectonics: The Earth’s lithosphere is divided into plates that move, causing earthquakes, volcanic eruptions, and the formation of mountains.

15. Geomorphology

  • Weathering and Erosion: Processes that break down rocks and transport materials.

  • Landforms: Mountains, plateaus, valleys, and rivers are shaped by tectonic activity, erosion, and deposition.

16. Climatology

  • Atmospheric Circulation: The global movement of air that influences weather patterns.

  • Jet Streams: Fast flowing air currents in the upper atmosphere that influence weather systems.

  • El Niño and La Niña: Phenomena that affect global weather, including Indian monsoons.

17. Oceanography

  • Ocean Currents: The movement of ocean water, influencing climate and marine life.

  • Marine Resources: Includes polymetallic nodules, fishery resources, and oil