Fact 1: Mechanical weathering is when rocks are broken down by mechanical means.

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

Given the two facts above, answer the question "what can break down rocks?" with the following options: 
- Jellyfish
 - sea urchins
 - deltas
 - erosion
 - ice wedging
 - room temperature
 - clouds
 - cliffs


 

     ice wedging    