Why is deposition as the opposite of erosion? Give examples of these processes.

Deposition is a "conservative" while erosion is a "destructive" mechanism.

Explanation:

Deposition is when the surface is exposed to sediments, dirt, or rocks. It's the inverse of erosion. Deposition is a positive method since it builds or produces surface features. As over time wind, water and other forces will wear away sediments, so must sediments be accumulated as well. The process through which water vapor transforms spontaneously to ice in sub-freezing air, without first becoming a liquid is one of the instance of deposition.

In earth science, erosion is the activity of surface mechanisms that detach soil, rock, or soluble material from one place on the crust of the Earth, and then transferred it to another. For an instance wind carries away small pieces of rock from a mountain side.