Complete Geography Notes for UPSC, PSC, and SSC (Part-1)

Chapter 1: Geomorphology

The Study of Landforms and Earth’s Internal Processes

1.1 Structure of the Earth

  • Earth has concentric layers:
    • Crust: 5–70 km thick; continental (sial) and oceanic (sima)
    • Mantle: Extends to 2900 km; asthenosphere is part of upper mantle
    • Core: Outer (liquid), Inner (solid); iron-nickel composition

Discontinuities:

  • Moho: Crust–mantle
  • Gutenberg: Mantle–outer core
  • Lehmann: Outer–inner core

UPSC Angle: “Why S-waves do not travel through outer core?” → They can’t pass through liquid.

1.2 Earth Movements

Endogenic (internal forces): Build landforms

  • Folding (Himalayas), Faulting (Rift Valleys), Volcanism

Exogenic (external forces): Degrade landforms

  • Weathering, Erosion, Mass wasting, Deposition

1.3 Plate Tectonics Theory

  • Developed from Continental Drift (Wegener) + Sea Floor Spreading
  • Lithosphere divided into 7 major plates and several minor ones
  • Plate boundaries:
    • Divergent: Mid-Atlantic Ridge
    • Convergent: Himalayas (continent–continent), Andes (ocean–continent)
    • Transform: San Andreas Fault (USA)

Important: Subduction zones = volcanic + earthquake activity
Prelims MCQ Trend: Plate matching with landforms

1.4 Earthquakes

  • Sudden energy release → seismic waves
  • Focus: Origin point, Epicenter: Surface point
  • Richter Scale: Measures magnitude
  • Mercalli Scale: Measures intensity (damage)

Seismic Waves:

  • P-waves: Fast, through solid & liquid
  • S-waves: Through solids only
  • Surface waves: Most destructive

Seismic Zones in India:

  • Zone V: Kashmir, NE India
  • Zone IV: Delhi, parts of Bihar
  • Zone III: Mumbai, Kolkata

Mains Relevance: “Urban earthquakes are deadlier due to human vulnerability. Discuss.”

1.5 Volcanoes

  • Opening in Earth’s crust emitting lava/gases/ash
  • Types by Activity:
    • Active (Barren Island), Dormant (Vesuvius), Extinct (Deccan Traps)

Volcanic Landforms:

  • Intrusive: Batholith, Laccolith, Sill
  • Extrusive: Shield volcano, Composite cone

Pacific Ring of Fire = Most active volcanic belt

Prelims Favorite: Match volcano type with location
Mains Angle: “Volcanism and plate tectonics are linked – explain with examples.”

1.6 Weathering and Mass Wasting

  • Weathering: Disintegration of rocks in place
    • Mechanical (frost, exfoliation)
    • Chemical (oxidation, hydration)
    • Biological (roots, lichens)

Mass Wasting: Downhill movement (landslide, soil creep)

Prelims Alert: Match type of weathering with climate
Mains Angle: “Landslides are increasing in Western Ghats – explain with geography”

1.7 Erosional and Depositional Landforms

Fluvial (River):

  • Erosional: V-shaped valley, gorges, waterfall
  • Depositional: Meanders, floodplains, delta, ox-bow lake

Aeolian (Wind):

  • Erosional: Mushroom rock
  • Depositional: Sand dunes (barchans)

Glacial:

  • Erosional: U-shaped valley, cirque, arête
  • Depositional: Moraines, drumlins

Coastal:

  • Erosional: Cliffs, arches, stacks
  • Depositional: Beaches, spits, bars

Karst (Limestone):

  • Sinkholes, stalactites, stalagmites, caves

Prelims Pick: Delta type – arcuate (Ganga), bird-foot (Mississippi)
Mains Task: “River systems shape the Indian landscape – discuss with examples.”

Chapter 2: Climatology

2.1 Introduction to Climatology

  • Definition: Climatology is the scientific study of climate, analyzing long-term weather patterns and trends.
  • Importance: Understanding climate is crucial for agriculture, disaster management, and planning in India.​

2.2 Factors Influencing India’s Climate

  • Latitude: India’s position between 8°N and 37°N affects its tropical to subtropical climate.
  • Himalayas: Act as a barrier, preventing cold Central Asian winds, thus influencing the climate of the northern plains.
  • Thar Desert: Contributes to the development of the monsoon system by creating low-pressure zones.
  • Indian Ocean: Influences the monsoon winds and provides moisture for rainfall.
  • Altitude: Varied elevations lead to diverse climatic conditions across regions.​

2.3 Climatic Zones of India (Köppen Classification)

India’s climate can be categorized into several zones based on the Köppen system:​

  • Tropical Wet (Af): Found in the Western Ghats and northeastern states; characterized by high rainfall and humidity.
  • Tropical Wet and Dry (Aw): Covers central and southern India; marked by distinct wet and dry seasons.
  • Semi-Arid (BSh): Located in parts of Gujarat and the Deccan plateau; receives moderate rainfall.
  • Arid (BWh): Encompasses the Thar Desert region; experiences very low rainfall.
  • Humid Subtropical (Cwa): Includes the northern plains; hot summers and cool winters with moderate rainfall.
  • Mountain (H): Covers the Himalayan region; characterized by cold temperatures and snowfall.​

Note: For a detailed map illustrating these climatic zones, refer to the official resources provided by the Survey of India.​India Government

2.4 Seasons in India (As per Indian Meteorological Department)

  • Winter (January – February): Cool and dry conditions prevail.
  • Pre-Monsoon/Summer (March – May): High temperatures and occasional thunderstorms.
  • Southwest Monsoon (June – September): Major rainfall period due to monsoon winds.
  • Post-Monsoon/Retreating Monsoon (October – December): Withdrawal of monsoon with decreasing rainfall.​

2.5 Monsoons in India

  • Southwest Monsoon:
    • Onset: Early June over Kerala.
    • Coverage: Progresses northward, covering the entire country by mid-July.
    • Significance: Accounts for about 75% of India’s annual rainfall.
  • Northeast Monsoon:
    • Occurrence: October to December.
    • Impact: Primarily affects the southeastern coast, especially Tamil Nadu.

2.6 Climatic Regions (Stamp’s Classification)

Stamp’s classification divides India into the following climatic regions

  • Tropical Rainy Climate: Western Ghats, northeastern states.
  • Tropical Savanna Climate: Central and parts of southern India.
  • Humid Subtropical Climate: Northern plains and foothills of the Himalayas.
  • Mountain Climate: Himalayan region.
  • Arid and Semi-Arid Climate: Rajasthan, parts of Gujarat.​

2.7 Climatic Data of Major Cities

CityAvg Temp (°C)Annual Rainfall (mm)
Delhi25774
Mumbai272,200
Kolkata261,582
Chennai281,400
Bengaluru24970
Guwahati241,722
Jaipur25650

2.8 Impact of Climate on Agriculture

  • Crop Patterns: Monsoon-dependent crops like rice and pulses dominate.
  • Irrigation Needs: Regions with low rainfall rely heavily on irrigation.
  • Climate Change Effects: Altered rainfall patterns affect sowing and harvesting cycles.​

2.9 Climate Change and India

  • Rising Temperatures: Increase in average temperatures affects ecosystems.
  • Glacial Retreat: Himalayan glaciers are receding, impacting river flows.
  • Extreme Weather Events: Increased frequency of floods, droughts, and cyclones
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