Question.
Describe the erosional and depositional landforms of the arid environment. ( 25 Marks, 66th BPSC geography Optional Paper)
Examine critically Characteristics of topographical features in arid regions. ( UPPSC 2006)
Give a reasoned account of the development of landforms in an arid region. ( UPPSC 1997)
Answer.
A dry environment is an environment where evaporation is greater than precipitation. Hot deserts and cold deserts are examples of dry environments. Air and water are two geomorphic agents in a dry environment. In desert areas, torrential rainfall occurs for a limited period of time, due to which water along with wind is an active geomorphic agent.
The following are the erosional landforms in the arid environment:
- Pediment
- Monadnock or Inselberg
- Pediplain
- Mushroom rocks
- Zeugen
The following are the depositional landforms in an arid environment:
- Playas
- Sand dunes
- Longitudinal dunes.
- Transverse dunes.
Pediment:
The pediment is one of the most prominent erosional landforms in the arid region formed by water erosion with the following characteristics:
- Pediments are rocky floors with a gentle slope.
- Pediments are formed near the foot of the mountains.
- There may or may not be debris on it.
- Pediments are formed by horizontal erosion in the front of the mountains, which are usually formed by streams and floods.
Monadnock or Inselberg:
- As we know, pediments are formed at the foot of the mountain. Over time, there is a parallel retreat in the slopes due to backwashing.
- With the retreat of the pediment, the mountain front also retreats parallelly. Gradually, the remainder of the mountain is made up of hard rocks called the Monadnock or Inselberg.
Pediplains :
- Over time, relief landforms such as pediments and Inselberg get eroded to form a featureless plain called a peneplain. Pediplains are erosional landforms in arid environments.
Mushroom Rocks:
When winds erode more of the bottom of the rocks than the top of the rocks, the rock looks like a mushroom with a narrow base and a wide top, this is called mushroom landform.
Zeugen:
- When the rocks are eroded, the table shape is left, it is called Jeugen landform.
Playas:
Playas are depositional landforms in arid environments. Playas are formed in the following ways:
- When it rains heavily in the desert region, sediments from the mountains and hills get deposited in the center of the valleys.
- And an almost flat plain is formed, it is called playas.
- When sufficient water is available for a short period, the plain is covered by a shallow water body.
- There is also a good deposition of salts in the playa.
Loess
- In hot desert areas, where sufficient sand is available, winds transport the sand and deposit it unsorted way over large areas, called Loess.
Sand dunes:
Where sand is available in sufficient quantity, sand dunes are formed.
There are several types of sand dunes:
- Crescent Dunes
- Longitudinal Dunes
- Transverse Dunes
Crescent dunes:
Crescent dunes, also known as Barchans, are found in abundance in sandy deserts. The shape of the crescent-shaped dunes is like the letter "C". The wings of the crescent-shaped dunes come out in the direction of the wind.
Longitudinal Dunes:
- When the wind direction is constant and there is a lack of sand supply, longitudinal dunes are formed. Longitudinal dunes are usually of great length but less in height.
Transverse Dunes:
- Transverse dunes are formed perpendicular to the direction of the wind. It is formed when the wind direction is constant and there is a sufficient source of sand. It is of less height, the length is more.
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