Question

describe wind as a powerful agent of gradation with its erosional and depositional features.(One for each)​

Answer 1

$\large{\frak{\red{Answer}}}$

In the previous articles, we have been discussing various exogenic geomorphic agents like water (${\pmb{\mathbb{\text{\red{running water and groundwater}}}}}$) and ${\pmb{\mathbb{\text{\red{glaciers}}}}}$. We have seen the evolution of landforms due to these agents. In this post, we discuss in detail how the wind and the waves cause the evolution of various landforms on the earth surface.

${\huge{\pmb{\mathbb{\text{\red{Action of Winds:}}}}}}$

• The wind is the main geomorphic agent in the hot deserts.
• Winds in hot deserts have greater speed which causes erosional and depositional activities in the desert.
• The landforms which are created by erosional and depositional activities of wind are called as Aeolian Landforms.
• This process is not unique to the Earth, and it has been observed and studied on other planets, including Mars.
• An erg (also known as sand sea / dune sea / sand sheet if it lacks dunes) is a broad, flat area of desert covered with wind-swept sand with little or no vegetative cover. It is defined as a desert area that contains more than 125 square kilometres of aeolian or wind-blown sand and where sand covers more than 20% of the surface. Smaller areas are known as “dune fields”. The largest hot desert in the world, the Sahara, contains several ergs.

${\huge{\pmb{\mathbb{\text{Erosional Landforms due to Wind}}}}}$

1. Pediplains

• When the high relief structures in deserts are reduced to low featureless plains by the activities of wind, they are called as Pediplains.

2. 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.

3. Mushroom Tables

• Ventifacts are rocks that have been abraded, pitted, etched, grooved, or polished by wind-driven sand or ice crystals.
• These geomorphic features are most typically found in arid environments where there is little vegetation to interfere with aeolian particle transport, where there are frequently strong winds, and where there is a steady but not overwhelming supply of sand.
• Mushroom Tables / Mushroom rocks are Ventifacts in the shape of a mushroom.
• 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 with narrow pillars with broad top surfaces.

${\huge{\pmb{\mathbb{\text{Depositional Landforms of Wind}}}}}$

1. Sand dunes

• Dry hot deserts are good places for sand dune formation.
• According to the shape of a sand dune, there are varieties of sand dune forms like Barchans, Seifs etc.
• The crescent-shaped dunes are called as Barchans and they are the most common one.
• Seif is similar to Barchans but has only one wing or point.

2. Loess

• In several large areas of the world, the surface is covered by deposits of wind-transported silt that has settled out from dust storms over many thousands of years. These depositions are called as Loess.

$\bf{\pmb{\mathbb{\fbox{\red{Hope it's help you}}}}}$