When water seeps into cracks of rock, then freezes, expands, and creates a deeper crack.
This process is called frost wedging and it is a type of physical weathering. Here's how it works:
1. Water seeps into the cracks of rocks. This usually happens when the rock is porous or has several interconnected cracks and fractures.
2. When the temperature drops below freezing point, the water in the cracks freezes and turns into ice. As water freezes, it expands by about 9% in volume. This expansion exerts pressure on the surrounding rock.
3. The pressure from the expanding ice creates stress on the rock walls of the crack. Over time, this stress causes the rock to fracture and widen the crack.
4. When the ice eventually melts, it leaves behind a larger crack in the rock than before. This process can lead to the continuous widening and deepening of cracks.
5. With repeated cycles of freezing and thawing, the cracks can eventually become large enough to break off pieces of the rock, leading to the formation of small fragments or even larger boulders.
Frost wedging is particularly effective in regions with colder climates and where there are frequent freeze-thaw cycles. This process is one of the factors responsible for shaping landscapes, such as forming valleys, canyons, and rugged mountain terrains.