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
 - water vapor
 - the looseness of soil
 - mechanical weathering
 - freezing oxygen
 - fissures of hot, acidic water
 - looseness of dirt or compost
 - explosions


 

    mechanical weathering     