Q. Wind plays a major role in formation of different erosional and depositional land forms. In this light discuss the various types of land topography formed due to action of wind.
Structure of the answer:
- Introduction: Role of winds
- Various erosional features
- Various depositional features
The wind is the main geomorphic agent especially in the hot deserts. Winds have a dual role in creating Erosional landforms and other in creating Depositional landforms.
These geomorphic features are most typically found in arid environments where there is little vegetation, where there are frequently strong winds etc. The landforms which are created by erosional and depositional activities of wind are called as Aeolian Landforms.
The various erosional landforms are as follows:
- Pediplains: The high relief structures in deserts are reduced to low featureless plains by the activities of wind.
- Deflation Hollows: Deflation is the removal of loose particles from the ground by the action of wind. When deflation causes a shallow depression by persistent movements of wind, they are called as deflation hollows.
- Ventifacts: These are rocks that have been abraded, pitted, etched, grooved, or polished by wind-driven sand.
- Mushroom Tables: In deserts, a greater amount of sand and rock particles are transported close to the ground by the winds which cause more bottom erosion in overlying rocks than the top. This result in the formation of rock pillars shaped like a mushroom.
- Other forms: Inselbergs, Zeugen (formed when more resistant rock is reduced at a slower rate than softer rocks), Yardangs (ridge of rock formed usually parallel to the prevailing wind direction.
The various depositional landforms created by winds are as follows:
- Sand dunes: Dry hot deserts are good places for sand dune formation. There are varieties of sand dune forms like Barchans, Seifs
- Parabolic dunes: They are U-shaped and are much longer and narrower than barchans.
- Ripple Marks: These are depositional features on a small scale formed by saltation (transport of hard particles over an uneven surface in a turbulent flow of air).
- Loess: When the surface is covered by deposits of wind-transported silt that has settled out from dust storms.
This suggest that the wind plays an important role in erosion and deposition and consequent formation of new land forms.