Class 11 Geography: Geomorphic Processes

• Introduction

  • Definition: Processes that shape the Earth's surface through endogenic and exogenic forces.
  • Geomorphic Agents: Mobile mediums (running water, groundwater, glaciers, wind, waves) that remove, transport, and deposit earth materials.
  • Geomorphic Processes: Dynamic forces causing physical and chemical changes on the Earth's crust.

• Endogenic Processes

  • Origin: Energy derived from within the Earth's interior.
  • Diastrophism
    • All processes that move, elevate, or build up portions of the Earth's crust.
    • Orogenic processes: Mountain-building through folding and faulting.
    • Epeirogenic processes: Broad-scale uplift or warping of the continent.
    • Earthquakes: Sudden local shocks releasing energy.
    • Plate Tectonics: Horizontal movements of crustal plates.
  • Volcanism
    • Movement of molten rock (magma) onto or toward the Earth's surface.
    • Intrusive volcanism: Formation of batholiths, sills, dykes, etc.
    • Extrusive volcanism: Lava flows, volcanic cones, and ash.

• Exogenic Processes

  • Origin: Energy derived from the sun and atmospheric gradients.
  • Denudation
    • General term for weathering, mass movement, erosion, and transportation.
    • Stripping off of the Earth's surface.
  • Weathering
    • Action of elements of weather and climate on earth materials (in-situ process).
    • Chemical Weathering: Solution, carbonation, hydration, oxidation, and reduction.
    • Physical/Mechanical Weathering: Unloading, thermal expansion, freezing-thawing, salt crystal growth.
    • Biological Weathering: Contribution by vegetation, animals, and humans (e.g., burrowing, roots).
    • Significance: Soil formation, reduction of rocks, aids erosion.
  • Mass Movements
    • Downslope movement of rock debris under the direct influence of gravity.
    • Slow Movements: Creep, solifluction.
    • Rapid Movements: Earthflow, mudflow.
    • Landslides: Rapid to perceived sudden sliding of large rock masses.
  • Erosion and Deposition
    • Erosion: Acquisition and transportation of rock debris by geomorphic agents.
    • Deposition: Consequence of erosion; dropping of debris when agent velocity decreases.

• Soil Formation (Pedogenesis)

  • Definition: The specific process of soil development covering the Earth's surface.
  • Factors of Soil Formation
    • Parent Material: Underlying geological structure.
    • Topography: Slope angle and drainage.
    • Climate: Temperature and precipitation (most dominant factor).
    • Biological Activity: Flora, fauna, and microorganisms (humus formation).
    • Time: Duration for soil development.
  • Soil Profile: Vertical arrangement of soil horizons (A, B, C, R horizons).