Work of Wind Or Aeolian Landforms Wel-Come Dept. of Geography Topic Work of Wind Or Aeolian Landforms Presented By – Asst.Professor R.K. Pawar Dept. of Geography SSVPS Dhule’s late S.D.Patil alias Baburao dada arts, commerce & late M.D. Sisode science College Shindkheda dist.- Dhule (Maharashtra) INDIA

Abrasion:- Deflation:- Attrition:- Mechanism of Wind erosion:- Chapter: - 3 WORK OF WIND Mechanism of Wind erosion:- Deflation:- Deflation means blow away. It means that lifting of sand and dust particles into the air. Deflation is responsible for the creating depression or hollows. Abrasion:- Dust and sand particles transported by the wind strikes the obstacles like rocks and boulders in their way. The rocks are wearing down by scarping; rubbing scouring, polishing grooving etc. wind abrasion is comparatively less at ground level because wind velocity is retarded by friction. Attrition:- The dust and sand particles in air are carried from one place to the other, they collide with one another. Hence the sand and dust particles get smaller and rounded by friction. This process is called Attrition.

Erosional Land Forms associated with Work of Wind 1) Blow Out : The shallow depression produce in the desert by deflation termed as a blowout. When the surface rocks are soft then the blowout are formed. Due to the deflation action soft rocks are eroded. Depression and hallows are created in soft rocks, these known as blowout. Some blowouts are very large in size but they are shallow. Blowouts are observed in all desert of the world.

2) Mushroom Rock : The mushroom rocks are the results of abrasion action by the wind. The shape of the rock is like mushroom or umbrella. These rocks have broad upper part and narrow base. The wind carries larger fragments like the pebbles and sand. When a huge rocks lies in the way of strong wind that time wind strikes by pebbles, stone pieces and sand particles. Due to abrasion action by wind on all side of rock block, rock block becomes narrower slightly above from the base level while upper part is least affected. Hence it got such mushroom shaped. They are common in all desert area, such rock is known as ‘Gara’ in Sahara.

2) Mushroom Rock :

2) Mushroom Rock :

3) Yardangs: Due to the erosional action of wind on hard and soft rock, a peculiar feature comes into existence known as Yardang. In desert area, when hard and soft rocks lie parallel to each other, the soft rocks are eroded fastly than the hard rocks. The loose fragments of rock are transported from that place to another place by strong wind, leaving behind furrows. The hard rocks are seen above the furrows up to a height 7m. Yardangs are common in the Atacama Desert of Chile.

4) Zeugen Some times in a desert area hard and soft rocks layer lies horizontally. Due to the weathering fissures are developed in the hard rocks. The temperature in some desert is low during night. Due to low temperature at night, the water is freezes in fissures. At day time the frozen moisture melts. This alternate freezing and melting action of moisture (water) responsible for the widening of fissures. There also abrasion action of wind. The wind scores the rocks. The softer rocks are eroded fastly leaving behind tabular masses of hard rocks. This feature is known as Zeugen.

5) Inselbergs Inselberg is a German word. The meaning of Inselberg is residual hill. It looks like island situated in sea. It is a product of weathering and erosion in any climatic region. When surrounding soft rock is eroded by wind and only mound of hard rock is remains. Those remain rocks get dome shaped due to weathering. This dome shaped feature is known is ‘inselberg’. Inselberg are found near Lemme, Nigeria and in desert area of Australia.

Depositional Land Forms associated with Work of Wind Sand dunes The hill or ridge of sand which are formed by the deposition of sand by winds in desert area is known as sand dunes. Sand dunes are varying in shape, size and height. The following conditions are responsible for the creation of sand dunes. There should be abundance of sand. There should be high velocity of wind. There should be the presence of obstacles like trees, bushes, rock boulders etc. There should be level surface for the deposition of sand. The size of sand dunes ranges from 6 to 20 meters but same sand dunes are hundred of meters high. The slope of the wind ward direction of sand dunes is gentle and the slop of leeward direction is steep. The sand dunes are not stationary.

Sand dunes

2) Barkhan ‘Barkhans’ is a Turkistani word and its meaning is a hill of sand in a desert of Turkistan. The barkhans have crescent shape. Their outward portion is windward and inner one is leeward. The barkhans have two horns pointing downwind. They are form in group when there is ample supply of sand. There are numerous sand dunes of this type in the Barner region of Rajasthan.

2) Barkhan

2) Barkhan

3) Seif Dunes or Longitudinal dunes Sief dunes are formed parallel to the wind direction. They are extending hundreds of kilometres in length and average height of several hundred metres. Some sief dunes occurring in western desert of Egypt rise 60 metres in height and 70 km or more length. Sief dunes are more common in the deserts of Iran, Australia and Thar (India).

4) Ripples:- The sand deposits in the desert appear as wave like known as Ripples. Sand deposition is more on the wind ward side than on the leeward side. Ripples are formed at right angle to the direction of wind. The height and spacing of the ripples depend upon the size of sand particles and wind speed. Ripples are observed in Sahara Desert, Thar Desert etc. 5) Loess:- The fine particles of sand and dust are blown away by speedy winds. They are deposited in humid areas where the velocity of wind decreases. A deposition of such particles in humid areas responsible for formed of loess. Loess is usually yellow in colour. In the presence of water loess becomes very fertile and forms a good loamy soil. The larger area under the loess deposited is in North China, interior of USA, the steppe region of Asia etc.

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