Topographies created by Wind Erosion
- Kshatrak– Due to the action of air in desert regions, many rocks appear like a plant called ‘Kshatrak.’ This type of rock texture is called Chhatrak. There is a canopy of granite near Jodhpur (Rajasthan), which is called Nata in the Sahara desert. These are formed by natural wind erosion, channeling, and excavation. A flat rocky block rests on a thin pillar at its base. This natural texture is also called beetle.
- Geogen– Where soft layers are covered by hard layers, and when the upper hard layer is cut by continuous gusts of wind, the soft shell below is cut quickly. Sometimes the rock base is eroded, and the entire rock becomes crooked. These ridges are called Jiugen.
- Describe the Principle of Plate Tectonics.
- Give an Analytical Description of the Landforms Formed by River Erosion.
- Classify the Rocks and Describe their Composition, Characteristics, and Usage.
- Describe the Concept of the Normal Erosion Cycle Propounded by Davis.
- Yardang – When the air always moves in the same direction, and the strips of hard and soft rocks are located parallel to the flowing air, then the shape and form of the visible land become strange, and the form of the flat rock block becomes irregular like a ridge and groove. In the course of time, the whole region appears like rocky ribs. Like pillars, the visible central part is more cut, and the unevenly shaped vertical sides are called yardangs in the deserts of Central Asia.
- Dvipabha Giri- Due to the collective work of air and water, flat plains are presently based on rocks, and drains are formed on the surface. In such regions, here and their rocks remain standing like mounds. They are found in the desert of Rajasthan, and they are called Dweepam Giri.
- Trikotika – The upper part of the rocky pieces lying in the deserts gets smoothed by the blow of air, or they get scratched. These rock pieces are overturned or become sharp-edged Nagin’s initiative when the wind direction changes. Different types of carvings are found on these, and they are usually three-sided boulders. These types of rocky pieces are called Trikotika or Nepal. They are mostly found in the Sahara.
- Rock pillars are also formed by the combined effect of air and water on the top of which circular rocks are situated on the earth. These are called earth pillars.
- Rock-lattice Due to the blow of the dust particles flying in the air, the soft parts of the soft and hard rocks located on the way are cut off, and as a result, that rock becomes like a net. This is called rock lattice. Reticulated rocks of a sand layer are found in Raki Mountain. Due to the rapid wind erosion of a wide area of sandstone, the rock powder is scattered, and a rocky desert of rock fragments is formed.
Loose particles are transported from the ground level by the wind. The particles of sand or dust are carried by blowing from one place to another. Light and microscopic particles hang in the air, and their transport takes place in this condition. Heavy particles of large size keep rolling on the surface, but particles of medium size and weight sometimes do. They are transported by flying and sometimes rolling in the air. These actions depend on the velocity of the wind.
Air Deposition Operations
When wind slows down, sand or dust particles get collected on the ground, causing congestion when there is an obstruction in the passage of air. Most of the deposits are permanent and are called Aeolian deposits, named after the wind god Aeolus. In regions where deposition is more, deserts of sand and loess are formed, while in regions where erosion is more, rocky deserts are formed. The texture of these deserts depends on the composition of the parent rock and the gradual arrangement of the deposited materials.
Dunes are formed by the accumulation of sand, which requires an abundance of sand, a place for sand accumulation, high velocity of air, and obstruction in the airway. An infinite amount of sand is found in deserts, river beds, and sea coasts, which is why there is an abundance of sandstone stupas in these regions.
When the surface of dunes is disorganized, they are called draws. Valuka-that, ranging from 30 to 90 meters in height, are found in deserts. One-third to one-fourth of the area of each desert is covered in dunes. The country with the most dunes in the world is Arabia, where dunes cover one-third of the land surface. Only one-ninth of the Sahara desert is covered with sand, while the remaining part is scattered with rock blocks, air-formed stone blocks, and bedrock.
Dunes have a long and convex slope towards the windward side and a steep and concave slope towards the leeward side. The wind vortex in the direction away from the wind causes a cave-like formation in the sand mass, also known as the slip face.
On the leeward side of the slope, slight zigzag lines of sand are visible, and gradually their expansion and size increase because the sand particles are spread on both sides of the top by the vortex of air, causing the shape of the dunes to become crescent-shaped and elongated. If the wind blows from all sides, the shape of the mound becomes round. Thus, in different circumstances, the shape of the dunes is round at some places, crescent-shaped at some places, and flat at some places.
There are three types of sand dunes:
- Longitudinal Sand Dunes: These dunes are formed in both desert and desert-type areas. They originate from a great amount of sand and a lack of vegetation. Sand particles aggregate vertically like columns, and the series are usually parallel, presenting a tooth-like shape. In the Sahara desert, this type of dune is called Seif. Air prevails in it, and their existence is possible due to the modification of crooked and different dunes.
- Transverse Sand Dunes: Their expansion is perpendicular to the wind direction. They are formed by light air in the deep sandy country and are often found on the banks of rivers and lakes. There is a small strip between the parallel rows of dunes, in which light whirlpools of air are created, which keep deepening the central part by blowing fine sand.
- Parabolic Sand Dunes: In this type of sand dune, there is a gentle slope on the windward slope, or as a result, friction pits are formed on it. The windward slope is steeper where the sand particles are deposited. Windward dunes of coastal areas are examples of this.