Landforms and Their Evolution

(NCERT Class 11 – Fundamentals of Physical Geography, Chapter 7)


Meaning and Concept

  • Landform: Small to medium tracts of the Earth's surface such as valleys, hills, and plains.

  • Landscape: A combination of several related landforms over a large area.

  • Evolution of Landforms: Sequential transformation of landforms due to geomorphic processes; comparable to stages of life—youth, mature, old age.

Two key aspects:

  1. The processes shaping landforms (erosion, weathering, deposition, etc.).

  2. The stages of their development or evolution.


Agents of Geomorphic Change

AgentMajor ProcessesExample Landforms
Running WaterErosion, transportation, depositionValleys, gorges, peneplain, deltas
GroundwaterSolution, precipitationSinkholes, caves, stalactites
GlaciersAbrasion, pluckingCirques, moraines, drumlins
WavesErosion and depositionCliffs, beaches, spits, lagoons
WindDeflation, abrasionPediments, dunes, loess

Running Water Landforms

Erosional

  • Valleys: Form from rills → gullies → V-shaped valleys → gorges → canyons.

  • Potholes/Plunge Pools: Circular depressions formed by swirling pebbles.

  • Incised Meanders: Deep meanders cut into rock surfaces.

  • River Terraces: Remnants of old floodplains at higher levels.

Depositional

  • Alluvial Fan: Cone-shaped deposit of coarse material at mountain base.

  • Floodplain: Flat area of fine deposits along a river.

  • Natural Levees: Raised banks formed during floods.

  • Point Bars (Meander Bars): Deposits on the inner bends of meanders.

  • Deltas: Deposits at river mouths, graded from coarse to fine sediments.


Groundwater (Karst Topography)

Erosional

  • Sinkholes (Dolines): Funnel-shaped depressions formed by solution.

  • Uvalas: Merged sinkholes.

  • Limestone Pavement/Lapies: Grooved surfaces formed by solution.

  • Caves: Formed along bedding planes due to dissolution.

Depositional

  • Stalactites: Deposits hanging from the cave ceiling.

  • Stalagmites: Deposits rising from the cave floor.

  • Columns or Pillars: Formed when stalactites and stalagmites join.


Glacial Landforms

Erosional

  • Cirque (Corrie): Bowl-shaped hollow where glacier originates.

  • Horn: Sharp peak formed by several cirques (e.g., Matterhorn).

  • Arête: Knife-edge ridge between cirques.

  • U-shaped Valley: Glacial trough formed by erosion.

  • Fjord: Submerged U-shaped valley.

Depositional

  • Moraines: Ridges of debris; types include terminal, lateral, medial, ground.

  • Eskers: Long sinuous ridges formed by meltwater streams.

  • Drumlins: Elongated hills with a steep stoss and gentle lee side.

  • Outwash Plains: Stratified deposits beyond terminal moraine.


Marine (Wave) Landforms

Erosional (High Rocky Coast)

  • Sea Cliffs, Wave-cut Terraces, Sea Caves, Stacks.

Depositional (Low Sedimentary Coast)

  • Beaches, Bars, Barrier Bars, Spits, Lagoons, Coastal Plains.


Aeolian (Wind) Landforms

Erosional

  • Pediments: Gently sloping rock surfaces at mountain bases.

  • Pediplains: Coalesced pediments forming broad plains.

  • Mushroom Rocks, Yardangs: Streamlined ridges shaped by wind erosion.

Depositional

  • Sand Dunes: Types include barchans, longitudinal, and parabolic.

  • Loess: Fine, wind-blown silt deposits.