What is the relationship between weathering, erosion, deposition, and changes in the Earth's surface?
Weathering and erosion break down surface structures. Deposition builds them up.
The earth's surface layer is constantly changing through the processes of weathering (meaning primarily wind erosion here) and erosion (meaning primarily water weathering here) and deposition.
The source material for the deposition is the material previously eroded by wind or water. Thus, there is a constant cycle of breakdown and recycling, augmented by the tectonic and volcanic upheavals that move deposited materials back to the surface.