Which event is an example of physical weathering
The Correct Answer and Explanation is:
Correct Answer:
Water freezing in the cracks of a rock
Explanation
Physical weathering, also known as mechanical weathering, refers to the process of breaking down rocks into smaller pieces without changing their chemical composition. One classic and effective example of physical weathering is when water enters the cracks of a rock, freezes, and then expands.
This process is called frost wedging or freeze-thaw weathering. When water seeps into the tiny cracks and pores of rocks and temperatures drop below freezing, the water turns into ice. As it freezes, water expands by about 9 percent. This expansion creates immense pressure on the surrounding rock, forcing the crack to widen. Over repeated cycles of freezing and thawing, the cracks continue to grow until pieces of the rock eventually break off. This process is especially common in climates where temperatures frequently rise above and fall below the freezing point.
Unlike chemical weathering, which involves the alteration of a rock’s mineral composition due to reactions with substances like acids or oxygen, physical weathering simply changes the rock’s shape or size. The minerals stay the same, but the rock is fragmented into smaller pieces.
Other types of physical weathering include abrasion, where rocks grind against each other due to wind, water, or glaciers, and exfoliation, which involves layers of rock peeling away due to pressure release. However, the freeze-thaw cycle is among the most impactful, especially in mountainous and temperate regions.
This type of weathering contributes significantly to landscape changes over time. It helps create soil by breaking larger rocks into sediment and also contributes to the formation of cliffs, valleys, and rockfalls. Understanding physical weathering like frost wedging is important in geology, construction, and even historical preservation, as structures built with stone can degrade due to repeated freeze-thaw cycles.
