Here's why:

* Erosion is the process of wearing away and transporting rock, soil, and other materials. This happens due to forces like wind, water, ice, and gravity.

* Deposition is the process where these eroded materials are dropped or settled in a new location.

Think of it like a river carrying sand downstream. The river (water) is eroding the land, and the sand is being transported. Eventually, the river slows down, and the sand is deposited, forming a delta or sandbar.

Here's a simple example:

1. Erosion: Wind erodes sand dunes, carrying the sand away.

2. Deposition: The wind slows down, and the sand is deposited in a new location, forming a sandbar or another dune.

So, erosion and deposition are two sides of the same coin, constantly shaping and reshaping the Earth's surface.