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Weathering Processes for Frost and Ice

Frost and ice change the landscape by mechanical weathering. A cycle of freezing and thawing causes frost and ice to act like wedges to break rocks apart. More than one-third of Earth's surface is changed by the mechanical weathering of frost and ice.

Mechanical Weathering
- Mechanical weathering is a process that changes the landscape by breaking rocks into smaller pieces. The landscape changes as rocks continue to break down over time.
Frost Action
- Frost action is a type of mechanical weathering that occurs when water in rocks freezes and thaws. Frozen water causes rocks to crack between 5 and 25 degrees Fahrenheit. Rocks weathered by frost action break into angular fragments.
Freeze-Thaw Cycle
- The freeze-thaw cycle is the main process that causes frost and ice weathering. Water seeps into rocks and expands when it freezes. When water freezes, its volume increases by about 9 percent. The expansion causes the rocks to crack. Each time frost and ice thaw, water seeps into the new cracks formed from the previous freeze. As the cycle repeats, more cracks form.
Ice Wedges
- Ice wedges are another process of frost action. When a crack forms, the freeze-thaw cycle can cause an ice wedge to develop. A wedge-shaped mass of ice extends deeper and grows wider beneath the surface with each season of freezing. Ice wedges push soil out of the way, forming a hill on the surface.

Nature