Fact 1: Ice wedging is when ice causes rocks to crack by expanding in openings.

Fact 2: Water expands as it freezes into ice.

Given the two facts above, answer the question "How does water crack rocks?" with the following options: 
- Turning to silt
 - bottom of feet
 - Turning to ice
 - Getting hot
 - erosion
 - Mixing with salt
 - lowered energy cost
 - Movement


 

   Turning to ice      