Block disintegration is a mechanical weathering process prevalent in arid desert regions. What is the correct chronological sequence of steps in the breakdown of rocks by block disintegration?
- 1Exposed rock absorbs intense heat from solar radiation during the day, causing its outer layers to expand.
- 2Rapid temperature drops at night cause the rock outer layers to contract.
- 3Repeated expansion and contraction cycles set up internal stress along joint lines.
- 4The rock fractures and splits into large, angular blocks along its joint planes.
Answer
The correct sequence begins with daytime thermal expansion of the rock, followed by nighttime thermal contraction, leading to repeated stress along joints, and culminating in the rock fracturing into angular blocks.
Block disintegration occurs due to large diurnal temperature variations in arid regions. Heating during the day leads to expansion, while cooling at night leads to contraction. Over time, these recurring cycles generate stresses along joint lines, eventually causing the rock to fragment into large rectangular or angular blocks in-situ.
Step-by-Step Solution
Key Concept
Thermal expansion and contraction (block disintegration) in physical weathering