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

Fact 2: Ice wedging is the most important form of mechanical weathering.

Given the two facts above, answer the question "What do cycles of freezing and thawing water cause?" with the following options: 
- Metling snow
 - Mechanical weathering
 - the looseness of soil
 - fissures of hot, acidic water
 - exposure to cold
 - Plant growth is reduced
 - heat production
 - looseness of dirt or compost


 

  Mechanical weathering       