Thermal characterization of ancient hearths from the cave of Les Fraux (Dordogne, France) by thermoluminescence and magnetic susceptibility measurements

Numerous sorts of evidence of fires were observed in the cave of Les Fraux (Dordogne, France) and in particular the effects of fire on sediment were studied for a better understanding of their use centuries ago. Our present objective is the evaluation of the firing intensity by determining the past temperature (paleotemperature) attained by the topmost sediment of the archaeological fires. The principle of paleotemperature determination is based on the thermoluminescence (TL) properties of quartz and the magnetic susceptibility of the sediment. By comparing the TL signal of anciently heated quartz to the TL signal of thermal references made in the laboratory, we were able to obtain a maximal equivalent temperature attained for each sample extracted from ancient fires. The magnetic susceptibility (previously measured on the hearth surface) could thus be estimated as a function of temperature. The main result of this study is the temperature mapping of the hearth which can be used as meaningful information about the ancient firing intensity.

► We developed a new methodology for thermal characterization of ancient hearths.
► Magnetic susceptibility was measured on the hearth surface.
► Paleotemperatures attained by the sediment were determined by TL measurements.
► Magnetic susceptibility values were estimated as a function of temperature.
► Thus a qualitative scale of firing intensity can be given by the temperature mapping.