Geography Playlist
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The Universe and the Earth
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Atmosphere and its composition
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Atmospheric Temperature
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Atmospheric Moisture
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Air Mass, Fronts & Cyclones
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Evolution of Earths Crust, Earthquakes and Volcanoes
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Interior of The Earth
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Landforms
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Geomorphic Processes
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Movement of Ocean Water
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Oceans and its Properties
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12
Climate of a Region
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13
Indian Geography - introduction, Geology
5 topics
14
Physiography of India
27 topics
15
Indian Climate
20 topics
16
Indian Drainage
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Soil and Natural Vegetation
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Mineral and Energy Resources, Industries in India
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Indian Agriculture
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Chapter 13: Indian Geography - introduction, Geology
Chapter Test5 topics•Estimated reading: 15 minutes
India’s Size and Extent
Key Point
India is the seventh-largest country in the world with a land area of 3.28 million sq. km, covering 2.4% of the global geographical area. Its vast latitudinal and longitudinal spread influences its climate, culture, and diversity.
India is the seventh-largest country in the world with a land area of 3.28 million sq. km, covering 2.4% of the global geographical area. Its vast latitudinal and longitudinal spread influences its climate, culture, and diversity.
Detailed Notes (40 points)
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Size
Seventh-largest country in the world by area.
Total Area: 3.28 million sq. km.
Accounts for about 2.4% of the world’s total geographical area.
Latitudinal and Longitudinal Extent
Mainland lies between 8°4’N and 37°6’N latitudes and 68°7’E and 97°25’E longitudes.
Both latitude and longitude spread is nearly 30°.
North to South length: ~3214 km (Indira Col to Kanyakumari).
East to West width: ~2933 km (Rann of Kutch to Kibithu, Arunachal Pradesh).
Tropic of Cancer Passing States
1. Gujarat
2. Rajasthan
3. Madhya Pradesh
4. Chhattisgarh
5. Jharkhand
6. West Bengal
7. Tripura
8. Mizoram
Time Zones in India
India follows a single time zone, Indian Standard Time (IST).
IST is based on longitude 82°30’E, passing through Mirzapur (Uttar Pradesh).
IST = UTC + 5 hours 30 minutes.
CSIR-NPL, New Delhi maintains Indian Standard Time using cesium atomic clocks.
Indian Standard Meridian Passing States
1. Uttar Pradesh
2. Madhya Pradesh
3. Chhattisgarh
4. Odisha
5. Andhra Pradesh
Extreme Points
Northernmost: Indira Col (Ladakh).
Southernmost: Indira Point (Great Nicobar, Andaman & Nicobar Islands).
Southernmost (Mainland): Vivekananda Rock, Kanyakumari (Tamil Nadu).
Easternmost: Kibithu (Arunachal Pradesh).
Westernmost: Guhar Moti (Gujarat).
Boundaries of India
Land Boundary: ~15,200 km.
Coastline: ~7,516 km (including islands).
- Mainland Coastline: ~6,100 km.
- Island Coastline (Andaman & Nicobar, Lakshadweep): balance.
Extreme Points of India
| Direction | Place |
|---|---|
| North | Indira Col (Ladakh) |
| South | Indira Point (Great Nicobar) |
| South (Mainland) | Vivekananda Rock, Kanyakumari |
| East | Kibithu (Arunachal Pradesh) |
| West | Guhar Moti (Gujarat) |
Mains Key Points
India’s vast latitudinal extent explains diversity in climate, agriculture, and vegetation.
Single time zone creates challenges for northeastern states (calls for second time zone debate).
Extensive coastline supports maritime trade, security, and blue economy.
Geographical extent influences India’s cultural and linguistic diversity.
Prelims Strategy Tips
Tropic of Cancer passes through 8 Indian states.
IST is based on 82°30’E longitude through Mirzapur (UP).
India’s latitudinal extent is ~30°, affecting climate diversity.
Southernmost point: Indira Point (submerged during 2004 tsunami).
India as a Tropical Country & Its Neighbouring Countries (Expanded)
Key Point
India is tropical climatically because the Himalayas block cold temperate winds and the entire landmass south of them is governed by monsoon systems. India’s 15,200 km long land boundary touches 7 nations and 7,516 km of coastline connects it to the Indian Ocean, making it a strategic pivot in South Asia.
India is tropical climatically because the Himalayas block cold temperate winds and the entire landmass south of them is governed by monsoon systems. India’s 15,200 km long land boundary touches 7 nations and 7,516 km of coastline connects it to the Indian Ocean, making it a strategic pivot in South Asia.
Detailed Notes (12 points)
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Why India is a Tropical Country?
# Physical Reasons
India lies almost entirely south of the Himalayas, cutting it off from temperate winds.
Monsoons dominate the climatic system with hot summers, heavy seasonal rainfall, and mild winters.
Location: Tropic of Cancer divides the country almost in half, but tropical conditions prevail over most regions.
Peninsular India surrounded by seas moderates climate, adding to tropical character.
# Cultural Reasons
Tropical crops dominate: rice, sugarcane, cotton, tea, jute, spices.
Prevalence of tropical diseases like malaria, dengue, chikungunya.
Lifestyle adaptations: houses with sloping roofs in heavy rainfall areas, mud houses in hot plains.
Festivals and agriculture linked to monsoon cycle – e.g., Onam, Bihu, Pongal.
Settlements and occupations (fishing, paddy farming, forestry) show tropical patterns.
India’s Neighbouring Countries (Borders & Issues)
| Country | Border Length (km) | Bordering States/UTs | Facts | Major Issues |
|---|---|---|---|---|
| Afghanistan | 106 | Ladakh (Gilgit-Baltistan under Pakistan) | Shortest border, Durand Line (1893) | Entire stretch under Pakistan’s illegal occupation |
| China | 3488 | Ladakh, Himachal Pradesh, Uttarakhand, Sikkim, Arunachal Pradesh | Separated by LAC; disputed in Aksai Chin and Arunachal Pradesh | 1962 war; Galwan clash 2020; China claims Arunachal as 'South Tibet' |
| Nepal | 1752 | Uttarakhand, Uttar Pradesh, Bihar, West Bengal, Sikkim | Defined by Treaty of Sugauli (1816) | Kalapani-Limpiyadhura-Lipulekh & Susta disputes |
| Bhutan | 699 | Assam, Arunachal Pradesh, West Bengal, Sikkim | Peaceful border; India provides security assistance | China’s attempts in Doklam (2017 standoff) |
| Bangladesh | 4098 | Assam, Tripura, Mizoram, Meghalaya, West Bengal | Longest border; settled enclaves via 2015 Land Boundary Agreement | Illegal migration, river water sharing (Teesta issue) |
| Myanmar | 1643 | Arunachal Pradesh, Nagaland, Manipur, Mizoram | Border runs along Brahmaputra–Irrawaddy watershed | Cross-border insurgency, drug & arms trafficking |
| Sri Lanka | Maritime | Tamil Nadu (via Palk Strait) | Connected by Adam’s Bridge/Ram Setu | Kachchatheevu Island issue, Tamil fishermen arrests |
| Pakistan | 3323 | J&K, Punjab, Rajasthan, Gujarat | Borders include IB, LoC, Sir Creek | Terrorism, PoK & Gilgit-Baltistan, Sir Creek maritime dispute, Siachen Glacier conflict |
Mains Key Points
India’s tropical character influences monsoon-dependent agriculture and human settlements.
Geopolitical importance: India borders nuclear powers (China, Pakistan) and Least Developed Countries (Nepal, Bhutan, Myanmar, Bangladesh).
Strategic chokepoints: Palk Strait (Sri Lanka), Siliguri Corridor (Chicken’s Neck) with Nepal & Bhutan, Malacca Strait proximity via Andaman & Nicobar Islands.
India’s foreign policy shaped by border management: Look East with Myanmar, Act East via Southeast Asia, Neighbourhood First with SAARC nations.
Border disputes and cross-border challenges (migration, terrorism, smuggling) are central to India’s security architecture.
Prelims Strategy Tips
India’s longest border is with Bangladesh (4098 km), shortest with Afghanistan (106 km).
The only country India shares a maritime boundary with: Sri Lanka (via Palk Strait).
Tropic of Cancer passes through 8 Indian states – UPSC frequently asks this.
Doklam (2017) & Galwan (2020) incidents are current-affairs-linked border disputes.
Geological Structure of India – Archaean Rock System
Key Point
India’s geological history spans from the earliest Archaean rocks to the recent Indo-Gangetic alluvium. The Archaean rocks (older than 2500 million years) form the basement complex and are rich in metallic minerals, making them crucial for India’s economic geography.
India’s geological history spans from the earliest Archaean rocks to the recent Indo-Gangetic alluvium. The Archaean rocks (older than 2500 million years) form the basement complex and are rich in metallic minerals, making them crucial for India’s economic geography.
Detailed Notes (25 points)
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Major Geological Events
Formation of Peninsular India as part of the earliest crustal blocks of Earth.
Tertiary period: Upheaval of the Himalayas due to collision of Indo-Australian and Eurasian plates.
Pleistocene period: Formation of the Indo-Gangetic alluvial plains.
Rock Systems of India (as per Geological Survey of India)
1. Archaean Rock System (Pre-Cambrian, >2500 million years old)
2. Purana Rock System (Proterozoic to early Paleozoic, 1400–600 million years old)
3. Dravidian Rock System (Paleozoic to Mesozoic)
4. Aryan Rock System (Mesozoic to recent deposits).
The Archaean Rock System
Represent the oldest rocks of India, without any fossils → indicating no life existed then.
Primarily gneisses, schists, and granites.
Known as the 'Basement Complex' or 'Fundamental Gneisses' because later rock formations rest on them.
Rich in high-grade minerals like iron ore, manganese, copper, lead, gold, mica, bauxite, and aluminium silicates.
These rocks are often metamorphosed due to intense pressure and heat.
# Subdivisions
1. Archaean Gneisses and Schists:
Very old crystalline rocks, formed before 2500 million years.
Composition: gneiss (banded structure), schist (platy structure), granites.
Distribution: Two-thirds of Peninsular India → Dharwar plateau, Bundelkhand, Aravallis, Chotanagpur plateau, Meghalaya plateau.
Also found in roots of Greater Himalayas, Trans-Himalayan Zaskar, Ladakh, and Karakoram ranges.
2. Dharwar System:
Younger Archaean rocks, highly metamorphosed sediments and volcanic lavas.
Contain most of India’s metallic mineral wealth (iron, manganese, copper, gold).
Famous mineral belts: Bellary, Chitradurga, and Dharwar in Karnataka; Singhbhum in Jharkhand; Aravallis in Rajasthan.
Mineral Resources from Archaean Rocks
| Mineral | Major Regions |
|---|---|
| Iron Ore | Singhbhum (Jharkhand), Bellary & Chitradurga (Karnataka), Bastar (Chhattisgarh) |
| Manganese | Nagpur-Bhandara (Maharashtra), Balaghat (Madhya Pradesh) |
| Gold | Kolar Gold Fields (Karnataka), Hutti Mines |
| Mica | Jharkhand, Bihar, Andhra Pradesh, Rajasthan |
| Copper | Singhbhum belt (Jharkhand), Khetri (Rajasthan) |
| Granite | Andhra Pradesh, Tamil Nadu, Rajasthan, Karnataka |
Mains Key Points
Archaean rocks are economically significant as they hold India’s oldest and richest mineral deposits.
They are widely distributed in Peninsular India, forming the geological foundation of the subcontinent.
Their absence of fossils indicates no life existed during their formation.
The Dharwar system within the Archaean is crucial for industrial development due to its mineral wealth.
Himalayan roots also expose Archaean rocks, proving tectonic upliftment and ancient geology.
Prelims Strategy Tips
Archaean rocks are fossil-free and form the basement complex of Peninsular India.
Kolar Gold Fields in Karnataka are linked with Archaean rocks (gold mining).
Jharkhand’s Singhbhum belt is rich in both iron ore and copper from Dharwar rocks.
Rock Systems of India
Key Point
India's rocks are grouped into four broad systems: Archaean, Purana, Dravidian, and Aryan. They record Earth's geological history from the oldest crystalline basement rocks to the most recent alluvium.
India's rocks are grouped into four broad systems: Archaean, Purana, Dravidian, and Aryan. They record Earth's geological history from the oldest crystalline basement rocks to the most recent alluvium.
Major Rock Systems of India
| Rock System | Age/Period | Characteristics | Distribution | Economic Importance |
|---|---|---|---|---|
| Archaean (Gneiss, Schist) | Pre-Cambrian (>2500 million years) | Oldest rocks; crystalline, hard, unfossiliferous; form basement complex. | Peninsular India (Karnataka, Tamil Nadu, Chotanagpur, Bundelkhand, Aravallis), roots of Himalayas. | Rich in metallic ores: Iron ore, Manganese, Copper, Gold (Kolar), Mica (Jharkhand). |
| Dharwar System | 2500–1800 million years (Early Pre-Cambrian) | First sedimentary strata formed from weathering of Archaean rocks; metamorphosed; unfossiliferous. | Karnataka, Tamil Nadu, Chotanagpur Plateau, Meghalaya Plateau, Aravallis, Himalayas. | Iron ore (Bellary, Kudremukh), Manganese, Mica, high-grade ores. |
| Purana (Cuddapah & Vindhyan) | 1400–600 million years (Late Pre-Cambrian) | Old sedimentary formations, generally unfossiliferous; sandstone, shale, limestone. | Cuddapah Basin (AP, Odisha, Chhattisgarh, Aravallis); Vindhyan Basin (MP, UP, Rajasthan, Bihar). | Cuddapah: building stones, limestone; Vindhyan: sandstone, diamonds (Panna, Golconda), raw material for glass, cement, chemicals. |
| Dravidian | 600–300 million years (Cambrian–Carboniferous, Paleozoic) | Marine fossiliferous rocks, continuous sequence; evidence of Gondwana glaciation. | Himalayas (Pir Panjal, Kashmir valleys, Garhwal, Kumaon, Spiti, Shimla, Kangra); limited in MP (Umaria). | Marine fossils, coal beginnings, limestone. |
| Aryan (Composite) | 300 million years – Present | Youngest formations; fossiliferous; subdivided into Gondwana, Jurassic, Deccan Trap, Tertiary, Quaternary. | Peninsular basins, Rajmahal hills, Indo-Gangetic plains, Shivaliks, Himalayan foothills. | Coal, petroleum, natural gas, lignite, alluvium, fertile soils. |
| Gondwana (sub-division of Aryan) | Upper Carboniferous – Jurassic (~300–180 million years) | Basin-shaped depressions, rich in plant/animal fossils; climatic variations from glacial to desert. | Damodar, Mahanadi, Godavari valleys. | 98% of India’s coal reserves (low carbon content), shales, sandstone. |
| Jurassic System (Aryan) | 180–135 million years | Marine deposits, plant fossils. | Kutch, Jaisalmer, Rajasthan, Rajmahal hills. | Petroleum potential, building stones. |
| Deccan Trap (Aryan) | Late Cretaceous–Eocene (~66 million years) | Basaltic lava flows covering ~5 lakh sq. km; horizontal sheets. | Maharashtra, MP, Gujarat, parts of Karnataka, Rajmahal hills. | Regur (black cotton) soil, construction material. |
| Tertiary System (Aryan) | 65–2.6 million years | Marine & terrestrial sediments; fossil-rich. | Himalayan foothills (Shivalik, Assam, Kashmir). | Petroleum (Assam, Bombay High), coal (lignite), limestone. |
| Quaternary System (Aryan) | 2.6 million years – Present | Alluvium, deltaic deposits, recent sediments. | Indo-Gangetic plains, coastal plains, river valleys. | Most fertile agricultural soils, groundwater reserves. |
Mains Key Points
Indian rock systems reflect a complete geological record from Pre-Cambrian to Quaternary.
Each rock system is linked to mineral wealth: Archaean & Dharwar (metals), Purana (diamonds, limestone), Aryan (coal, petroleum, alluvium).
Gondwana system is crucial for India’s energy due to coal reserves.
Deccan Trap significantly influences Indian soils and agriculture.
Rock systems also preserve evidence of past climates, tectonic activity, and life evolution.
Prelims Strategy Tips
Gondwana → 98% of India’s coal (low carbon).
Panna (Vindhyan) → famous for diamonds.
Deccan Trap → black cotton soil source.
Cuddapah → building stones & limestone.
Rajmahal hills → Jurassic fossils + lava flows.
Passing of the Tropic of Cancer in India
Key Point
The Tropic of Cancer (23°30’ N) passes through the middle of India, dividing it into almost two equal halves — tropical south and subtropical north.
The Tropic of Cancer (23°30’ N) passes through the middle of India, dividing it into almost two equal halves — tropical south and subtropical north.
Geographical Significance of Tropic of Cancer
| Aspect | Details |
|---|---|
| Division of Country | Divides India into two parts: Northern half (subtropical/temperate) and Southern half (tropical). |
| Climatic Impact | Despite half of India lying north of the Tropic, the entire country is considered tropical due to monsoons and Himalayas blocking cold winds. |
| Latitude | 23°30’ North. |
States through which Tropic of Cancer Passes
| State | Region/Important Point |
|---|---|
| Gujarat | Near Jabalpur Hill, Tropic enters India. |
| Rajasthan | Passes through southern part of the state. |
| Madhya Pradesh | Cuts through central region — near Bhopal. |
| Chhattisgarh | Crosses through central tribal belt. |
| Jharkhand | Passes near Ranchi (famous as 'City of Tropic of Cancer'). |
| West Bengal | Crosses Krishnanagar, Baharampur region. |
| Tripura | Enters Northeast India. |
| Mizoram | Exits India into Myanmar. |
Mains Key Points
Discuss the climatic implications of the Tropic of Cancer’s passage — despite equal division, India is tropical due to monsoons and Himalayas.
Impact on agriculture and vegetation patterns in northern vs southern parts of India.
Cultural and geographical references (e.g., Ranchi city is noted for being near the Tropic).
Prelims Strategy Tips
Tropic of Cancer passes through 8 states — easily remembered by mnemonic **'Great Raj Makes Children Jump With Tiny Mind'** (Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, West Bengal, Tripura, Mizoram).
It passes almost through the center of India, near Ranchi (Jharkhand).
Divides India into tropical and subtropical halves.
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