Fire is undoubtedly an important behavioral adaptation. In the archaeological record – where several past occupations commonly overlap each other as time goes by –, the presence of a hearth can potentially lead to thermal changes of the underlying deposits. If this is the case, we need to understand to what extent, and under which conditions, temperatures change underneath a fire feature. We seek to better constrain what secondary (presumably unintentional) heating may have in our archaeological interpretations of burned artifacts, sediments and chronometric age estimations. We set out to answer these questions through controlled experiments on heat transfer under several experimental conditions. Our experimental apparatus (shown in the photo) consists of a high-temperature rounded heater, overlying a wooden box filled with different sediment types, and systematic recording temperatures in terms of both depth and lateral variations within the sediments. This initial experiment aims to provide a baseline for other similar experiments dealing with fire alteration of sediments and archaeological artifacts.