Mechanical weathering involves physically breaking rocks into fragments without changing the chemical make-up of the minerals within it. It's important to keep in mind that weathering is a surface or near-surface process. ... We call it erosion if the rock particle is moved by some flowing agent such as air, water or ice.
Weathering and erosion are geological processes that act together to shape the surface of the Earth. Erosion is displacement of solids (soil, mud, rock and other particles) usually by the agents of currents such as, wind, water, or ice by downward or down-slope movement in response to gravity or by living organisms.