Fact 1: Adelta is formed by deposition of sediment at the mouth of a river by water fanning out.

Fact 2: Erosion is responsible for wearing down exposed places and depositing sediment in level places.

Given the two facts above, answer the question "A delta is formed by " with the following options: 
- erosion
 - motion
 - plate shifts
 - flooding
 - loose soil
 - Earthworms
 - compression
 - gravity


 

 erosion        