With the aid of a new dating method utilizing the remnant magnetism of baked clay, the authors were able to deduce: the position of the material during firing, the orientation of the kiln walls, the geometric form of the firing chamber, and the reuse of certain materials. They applied this method to a Gallo-Roman tile-kiln excavated in Brittany and to the rejects of its production. The principal aim of this study was to give a practical demonstration of this new method by which displaced material can be dated. -- AATA