Here's why:

* Erosion: The process of wearing away and transporting rock, soil, and other materials.

* Deposition: The process of dropping or laying down eroded materials.

The agents of erosion (like wind, water, and ice) carry the eroded material. When these agents lose energy, they can no longer carry the material and it is deposited. This deposition process forms various landforms like river deltas, sand dunes, and glacial deposits.