The primary difference between weathering and erosion is that weathering refers to the erosion of natural substances without movement, while erosion includes movement of particles and surface materials. Weathering and erosion take place in the same locations and affect the same landforms, but erosion involves the movement of loosened particles and surface materials downwards via the force of gravity. Particles, such as small pieces of rock, sand and dirt dislodge during erosion, which requires a triggering force, typically wind, rain or ice.
Despite deriving from different sources, all types of erosion fall into one umbrella category. Weathering, however, takes place in two distinct processes, classifying as chemical or mechanical. Chemical weathering occurs when rocks undergo a change in chemical composition. Mechanical weathering refers to a physical change in rock surface and structure, while chemicals in those rocks remain unchanged. Weathering, like erosion, requires several agents to occur. These agents include water, ice, salt, temperature and even flora and fauna. Mechanical weathering occurs when rocks break down due to surrounding physical forces. Rapid heating and cooling of rocks triggers fracturing and breaking, changing the shape and sometimes texture of rock faces. Chemical weathering occurs with natural substances, like carbon dioxide, or with the combination of synthetic agents mixing with water and air. Chemical weathering affects small areas of land and larger landscapes, forming structures like sinkholes, limestone pits and caves.