This paper discusses the formation of layers of burnt herbivore dung in Neolithic, Eneolithic and Bronze Age Mediterranean caves. While these layers are clearly connected with transhumant pastoralism and the practice of keeping herds in the caves, their formation should not be seen as the result of purely practical and ‘rational’ reasons. In this paper, I develop an argument that they are remnants of a complex manipulation of substances which includes burning dung to make white ash. Thus instead of seeing dung as a culturally neutral refuse which has to be disposed of, we might see its burning and deposition as the cultural manipulation of potent substance.