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. Given these facts, most canyons are formed by rivers flowing and what type of erosion among the following options:
- forces
 - mechanical
 - uncontrolled
 - geological
 - Water expanding
 - flooding
 - thrust
 - barrel-shaped


 

    geological     