Chapter 1 Exogenetic Processes And Resultant Landforms Quiz

Exogenetic Processes and Landforms

• Landforms are of two types: primary landforms formed by earth movement and tectonic movement (endogenetic forces), and secondary landforms modified by exogenetic forces.
• Exogenetic processes include natural agents of gradation like rivers, glaciers, wind, sea waves, and groundwater, which continually modify the earth's surface.
• These processes can be identified by small and minute sculpturing on primary landforms.

Gradation

• Gradation is the levelling of the undulated surface of the earth, aiming to reach a certain limit known as the Base level of erosion.
• Gradation includes two processes: Aggradation and Degradation.

Aggradation

• Aggradation is the filling up of lowlands through the deposition of sand, silts, and pebbles by agents of gradation.
• Features of aggregation include deltas, sandbars, and floodplains.
• Example: The Ganga Delta is the result of aggradation by the river Ganga.

Degradation

• Degradation is the lowering of the earth's surface by agents of gradation like weathering, mass wasting, river, and glaciers.
• Lowering the height of a landform is the main aim of degradation.
• Example: The transformation of lofty mountains through Residual mountains, erosional plateau, and ultimately into erosional plains or peneplains.

The Role of Rivers in Shaping Landforms

• Rivers play an important role as agents of gradation on primary landforms.
• Rivers are part of the hydrological cycle, which involves evaporation, condensation, and precipitation.
• River basins are areas drained by a river, its tributaries, and distributaries, with the river playing a more important role in larger basins.

River Basins and Interfluves

• A river basin is usually delimited by a water divide.
• Example: The river Ganga basin is delimited by the Himalayas in the north and the Vindhya-Satpura-Maikal-Kaimur range in the south.
• An interfluve is a narrow, elongated, and plateau-like landform between two river valleys.