Chert procurement for inferring Neanderthal mobility in central western Iberia

Abstract

Lithic raw material sourcing is one of the most effective approaches for inferring exploitation territories during the Palaeolithic, including for Neanderthals. Certain raw materials, particularly chert, are especially well suited to this type of investigation because the distinctive characteristics of each geological source can be reliably identified through a combination of macroscopic observation, low-magnification analysis, and geochemical methods. With that in mind we questioned if chert sourcing would allow identification of territorial patterns for the Neanderthal populations of central Portugal, in western-most Iberia. To answer that question, we conducted an exploratory study comparing archaeological cherts from Gruta Nova da Columbeira, Praia Rei Cortiço and Mira Nascente with geological samples from nearby sources using macroscopic, low-magnification PIXE and pXRF analysis. Our results showed similarities between archaeological and geological cherts proving that the sites, sources and analytical protocols used were viable for such investigation and, therefore, can be developed and refined in the future. They also showed that correspondences between geological and archaeological cherts are limited to the area between the coast and the western façade of the first mountain ridge (Serra d’Áire e Candeeiros) to the east, and between the Cesaredas Plateau to the south and the River Lis to the north. This territory is adjacent to the area already delimited by chert sourcing and isotopic analysis for the Neanderthals that occupied Oliveira Cave, located at the southeastern façade of the same mountain range. This contributes to a better understanding of Neanderthal territorial patterns, which is particularly important in regions where research is underdeveloped and where identifying other patterns of variability, particularly across time, has proven difficult.

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