Temperature plays a significant role in the physical weathering of rocks through a process often referred to as thermal expansion and contraction. As temperatures fluctuate, rocks expand when heated and contract when cooled. This repeated cycle of expansion and contraction can create stress within the rock material, leading to the formation of cracks and fractures over time. The repeated temperature changes can weaken the rock structure, making it more susceptible to other types of weathering, such as ice wedging.
Regarding ice wedging (or frost wedging), here are the completed steps:
1. Cracks form in rocks.
2. **Water** seeps into the cracks.
3. The water in the cracks **freezes** and forms **ice**.
4. The ice expands and causes cracks and holes in the rock to **widen**.
5. Eventually, the rocks **break** apart.
Overall, ice wedging is particularly effective in regions where temperatures fluctuate around the freezing point, allowing water to freeze and thaw repeatedly, contributing to the breakup of rock material.