Depth domains of environmental geophysics

At first sight, environmental geophysics could be defined as “applied geophysics to solve environmentally relevant geosphere problems.” However, this formulation requires that the depth domain of the environmentally relevant geosphere (ERG) be delimited. Whereas the ERG upper boundary can easily be set at the earth's surface, the lower boundary still needs to be defined. In fact one might ask down to what depth,D, does the environment extend? On the basis of examples from Switzerland, it will be shown that the ERG can stretch over very different depth domains according to the problem in question.