Most canyons are formed by flowing rivers through erosion over long periods of time, and rivers contain 0.001 percent of the earth's water. Given these facts, what are most canyons caused by among the following options:
- erosion
 - Physical weathering
 - magic
 - Freezing temperature
 - Flowing water
 - ice wedging
 - Flowing gas
 - flooding


 

     Flowing water    