The series editor's foreword provides the opportunity to give the rationale for a series on the evolution of ore fields. In brief, it meets a need that I, an explorationist, perceived as I became involved in a multidisciplinary explo­ ration program in the late 1960s. We were looking for mines while prospecting at the ore-field scale. The practicalities demand that we know more about the ore field and that we do not just study individual deposits, the analogy being the three blind men who attempted to describe the elephant as they felt the trunk, ear, or leg. Two considerations in identifying ore fields are the different perception as one changes scale from orebody to ore field and the problem of stratigraphic classification and nomenclature in terms appropriate to metallogenesis. Two workers, Brock (1972) and Carey (1976), have been particularly con­ cerned with the different appreciation brought about by a change in scale.