The predominant process of weathering in desert regions is

1. Analyze the question You are asked for the main (predominant) type of weathering in desert regions.

2. Explain the concept Weathering is the breakdown of rocks in place, without transport. There are three main types:

• Physical (mechanical) weathering: rocks break into pieces with no change in their chemical makeup. Temperature changes, frost, and salt crystal growth cause it.
• Chemical weathering: rocks decompose through reactions with water, oxygen, and acids. It needs plenty of moisture and heat.
• Biological weathering: plants, roots, and animals break rocks down. It needs vegetation and organisms.

3. Step-by-step solution

• Deserts have very little rainfall, so chemical weathering is limited because it needs water.
• Deserts have sparse vegetation and few organisms, so biological weathering is minimal.
• Deserts have extreme temperature ranges. Days are scorching hot and nights are cold. Rocks expand in the heat and contract in the cold, repeatedly. This stress causes cracking, flaking, and breaking. This is called insolation weathering (thermal expansion and contraction), and it includes exfoliation (onion-skin peeling) and granular disintegration.
• Salt crystallization in rock pores also contributes to physical breakdown.
• Erosional (option C) is not a weathering process. Erosion involves the removal and transport of material by wind, water, or ice, so it is a different process altogether.

4. Answer The predominant process is physical weathering, which is option D.

5. Exam tip Remember: "Desert = Dry + Diurnal temperature range = Physical."

• Hot and wet (tropical rainforest) → chemical weathering dominates.
• Cold (polar/mountain) → frost action (physical).
• Dry and hot by day, cold at night (desert) → physical, by thermal expansion and contraction.

Also watch for "erosion" as an option. It is a distractor, because it is not a type of weathering.