Which is the last stage of physical weathering in rocks?
The last stage of physical weathering in rocks is known as exfoliation. Exfoliation occurs when outer layers of rock peel away in large sheets or slabs due to the release of pressure, expansion and contraction from temperature changes, or the removal of overlying material. It is a process that typically happens in rocks that have been deeply buried and then exposed through erosion or uplift.
How can temperature lead to weathering of rocks?
Temperature can lead to weathering of rocks through a process known as thermal expansion and contraction. When rocks are exposed to frequent and extreme changes in temperature, they expand when heated and contract when cooled. This repeated expansion and contraction weakens the rock's structure, leading to the breakdown or disintegration of the rock over time.
During daytime, rocks absorb heat from the Sun, causing them to expand. At night, as temperatures drop, the rocks cool down and contract. This continuous expansion and contraction create stress within the rock, leading to the formation of cracks or fractures. Over time, these cracks can grow and result in the fragmentation or disintegration of the rock, a process known as thermal fatigue.
The presence of water can also exacerbate the effects of temperature on rock weathering. When water enters existing cracks or pores in the rock, it can penetrate deeper into the rock mass. As temperatures fluctuate, the water within the cracks expands and contracts, exerting pressure on the surrounding rock. This process, called freeze-thaw weathering, can cause the expansion of water to enlarge existing cracks or create new ones, further breaking down the rock.
Overall, temperature-induced weathering is most effective in regions with large temperature ranges, such as deserts or areas with cold winters and hot summers. The combination of temperature fluctuations, water presence, and the resultant stress on the rock can accelerate the physical breakdown of rocks over time.