Soils are living dynamic systems that will (a) from time of soil formation, continue to mature and age as a result of natural ageing processes, and (b) from time of interaction with chemical contaminants, continue to change their physical, chemical, and biological soil attributes. The changes of soil attributes occur slowly or quickly in response to the impacts, depending on the circumstances. We consider environmental soil behaviour to be the time-related changes of soil attributes in response to the impacts from natural and anthropogenic stressors. The changes are evidences of soil evolution in the long process of soil maturation and ageing. The nature of a soil will change as it ages, and changes in the soil attributes that characterize a soil at any instance of time will be the result of the impacts from all kinds of stressors, such as the soil environment and anthropogenic stressors shown in Table 5.1 (Chapter 5). In short, evolution of a soil mass is a function of actions from (a) anthropogenic activities and events, and (b) regional natural environment processes. Accordingly, soil evolution is defined as the result of impacts of stressors on a soil from all sources (anthropogenic and natural ageing), from initial formation to time-present, and is manifested in terms of corresponding changes in its nature and attributes.