The Acheulian site of Cantera Vieja (Madrid, Spain) and the Lower to Middle Palaeolithic transition in central Spain

The Cantera Vieja archaeological site is situated in Madrid, Spain, an area rich in Miocene flint and that has revealed several quarries at Lower and Middle Palaeolithic sites in recent years. Our study presents a multidisciplinary examination of the site, featuring an analysis of its geological context, site formation processes, chronological framework, and assemblage characteristics. Formed on the interfluvial platform between the Manzanares and Jarama Rivers, the Cantera Vieja site was created during the late Middle Pleistocene (194 ± 13 to 215 ± 16 ka) by alternating alluvial and mass-movement colluvial processes. The site boasts a typical Acheulian assemblage, characterized by numerous handaxes and preforms, and bifacial shaping flakes and fragments, with a limited number of flake supports, non-Levallois flaking elements, and a few final retouched tools. However, comparison of the archaeological assemblages across the Iberian Peninsula, including Cantera Vieja, with those reported from other contemporaneous sites across different parts of Europe indicates that this technocomplex could have slight location-specific differences in its industrial evolution. Our study at Cantera Vieja allows us to discuss the presence of specific lithic expression in the context of the western Acheulian in general and its transition to the Middle Palaeolithic in Iberia in particular. At the same time, the characteristics of the Cantera Vieja assemblage provide potentially generalizable insights into the social organization of lithic production during the late Middle Pleistocene. We consider that Cantera Vieja must have fulfilled an essential role as a place for training and learning biface knapping.