Explanation
The correct option isWind blowing away sand
In arid and semi-arid regions, wind is a potent exogenic agent. The mechanism involves the lifting and removal of loose dust and sand particles from the ground surface, a process technically known as deflation.
Detailed Analysis:
- Earthquake is Incorrect: Earthquakes are endogenic (internal) forces caused by tectonic activity. While they can create structural depressions (such as grabens), they are not the primary surface process responsible for the widespread formation of shallow depressions in desert landscapes.
- Wind blowing away sand is Correct: Deflation (wind blowing away sand) lowers the land surface by removing loose material. Over time, this creates depressions known as deflation hollows or blowouts. In some cases, the wind erodes the surface down to the water table, resulting in the formation of an oasis. The Qattara Depression in Egypt is a prominent example formed by this process.
- River erosion is Incorrect: River erosion in deserts is typically associated with flash floods and ephemeral streams. It creates linear features like wadis (dry gullies) and contributes to pediment formation, but it is not the primary agent for creating enclosed depressions.
- Glacial movement is Incorrect: Glacial movement occurs in cold climates (cryosphere). It creates depressions such as cirques and kettle holes, which are unrelated to hot desert geomorphology.
Key Takeaway:
Deflation is the specific aeolian (wind) process responsible for removing loose sand and soil, thereby creating deflation hollows or blowouts in desert regions.