Petrographic and SEM-EDX characterization of Mousterian white/beige chert tools from the Navalmaillo rock shelter (Madrid, Spain)

Studying lithic raw material sourcing, processing and distribution is helpful when trying to reconstruct the territory, ecology, and cultural practices of Neanderthal groups. The use of multiple methods in such analyses allows for more refined characterizations to be made, helping to distinguish between materials better than any single method. Although 85% of the raw materials making up the Mousterian assemblage at the Navalmaillo Rock Shelter (Pinilla del Valle, Madrid Region of Spain) correspond to the available local geological resources, 10% is made of white/beige chert, which is not registered in regional geological cartography. Petrographic and scanning electron microscopy with energy dispersive X-ray spectroscopy analyses were performed to determine the origin of this white/beige chert and thus shed light on the procurement strategies of the Neanderthal groups that occupied the rock shelter. The results show this chert to correspond to three different types of rock: quartz-kaolinite rocks from dykes, cretaceous marine cherts, and quartz fillings of cavities/fractures. These findings are in accordance with the geological features and formations present in the Lozoya valley, as recorded during a geoarchaeological survey, and indicate that the Neanderthals occupying the center of the Iberian Peninsula possessed a detailed knowledge of the landscape that allowed them to exploit its resources during MIS5a-early MIS4.