Technical innovations during the recent Solutrean in the southwest of France: Recognition of heat treatment of chert and estimation of heating temperatures based on the example of Le Piage (Lot, France)

Abstract

The Solutrean technocomplex is characterized by the use of innovative techniques for stone tool knapping during the Upper Palaeolithic. These processes include the development of pressure retouch and heat treatment of silica rocks. These innovations remain unprecedented at the scale of the recent European Palaeolithic. The aim of our analysis is to acquire new information on the application of heat treatment, by investigating the heating technique and the lithic chaîne opératoire in which this treatment occurs. Macroscopic observations of the material combined with an infrared spectroscopic analysis of 69 archaeological samples provide new data on heat treatment in the Solutrean lithic series of Le Piage (Fajoles, Lot). Raw materials were heated in controlled conditions and to temperatures of 250–300 °C. We also found that only leaf-shaped pieces were heat-treated at Le Piage. Part of the results obtained by infrared spectroscopy reveal discrepancies with macroscopic observations. These data raise questions concerning the validity of common macroscopic criteria used for recognising heat treatment and shed light on some of the choices made by Solutrean groups.