You are presented with the question "Most canyons are formed by rivers flowing and what type of erosion?" and the following answer choices: 
- forces
 - mechanical
 - uncontrolled
 - geological
 - Water expanding
 - flooding
 - thrust
 - barrel-shaped

Now knowing that most canyons are formed by flowing rivers through erosion over long periods of time and geological erosion is natural occurring erosion over long periods of time, choose the best answer.


 

    geological     