ABSTRACT
This chapter presents the concepts that are essential to understanding the open and complex system of the soil. This major compartment of terrestrial ecosystems is continuously exposed to transformations, alterations, material and energy flows, infiltration, erosion and bioturbations, which may be entirely natural or more or less human induced. All these effects vary at different spatial scales, depending on geology, relief and climate, and give each soil a particular set of characteristics. A global vision of the soil system makes it possible to reconstruct the dynamics of their formation and to evaluate the role that human activities can play in the structure and composition of the current soil. In the frame of historical ecology projects, soils can be considered pedological archives of human history.
