Fact 1: Most canyons are formed by flowing rivers through erosion over long periods of time.

Fact 2: Smithfield Canyon, a deep gorge through the mountains, dominates the view to the west.

Given the two facts above, answer the question "What are formed by flowing rivers through erosion over long periods of time." with the following options: 
- streams
 - soft soil
 - patch reefs
 - flooding
 - Sediment
 - seas
 - deep gorges
 - wildfires


 

       deep gorges  