While anthropology has recently started analysing the use it makes of the notion of “field” and, in particular, of its history, the geological connotation of this metaphor has not, so far, been scrutinized. This state of things was bound to attract the attention of an ethnographer interested in the search for underground water: he meets hydrogeologists, dowsers and their clients, for whom “the field” also corresponds to a variety of practices and preoccupations. Any metaphor is, to some extent, “mined” and that of the field not more so than others. Still, it appears advisable to examine the implications of the attraction which it has exerted on anthropologists and the ways in which we use it to express our Western representations of productive and organizational activities in the domain of knowledge.