Fact 1: Cycles of freezing and thawing water cause ice wedging.

Fact 2: The processes of weathering, and water or ice wedging may assist in this.

Given the two facts above, answer the question "What causes ice wedging?" with the following options: 
- Metling snow
 - Condensation
 - The sun
 - friction
 - Gravitational pull
 - mechanical
 - Weathering
 - Animals


 

       Weathering  