A delta is formed by 
erosion motion plate shifts flooding loose soil Earthworms compression gravity
A B C D E F G H
Erosion is responsible for wearing down exposed places and depositing sediment in level places.
a delta is formed by erosion 
A delta is formed by  (A) erosion (B) motion (C) plate shifts (D) flooding (E) loose soil (F) Earthworms (G) compression (H) gravity