Raw materials procurement strategies at the Ciota Ciara cave: new insight on land mobility in north-western Italy during Middle Palaeolithic
Description
The importance of the Ciota Ciara cave for the understanding of the Middle Palaeolithic peopling of Piedmont (north-western Italy) is known since the 60s but it is just since 2009 that systematic and multidisciplinary archaeological excavations are ongoing at the site. In this region, studies about Palaeolithic are quite underdeveloped and the proposed research represents the first attempt to understand Middle Palaeolithic land mobility in the region. The lithic assemblage found is composed by 7046 artefacts and different raw materials are involved in the production of lithic artefacts. Vein quartz is the main exploited raw material in all the archaeological layers followed by spongolite, a local variety of chert, and by a better-quality grey/black flint. For these rocks the reduction sequences are complete while other raw materials are sporadically attested all along the sequence (opal, jasper and milonite) and probably exploited out of the site. Rhyolite and radiolarite are present in different proportions in all the archaeological levels and are represented almost exclusively by retouched tools and by small flakes belonging to the reshaping or re-sharpening of the tools’ edges. The proposed research focuses on the identification of the supply areas of lithic raw materials in order to define the land mobility of the human groups that inhabited the cave during Middle Palaeolithic. The study involves both local and allochthonous raw materials to understand the mobility range on a local and sub-regional scale. Starting from the idea of evolutionary chain, a specific methodology has been developed for vein quartz, aimed at the identification of the most probable secondary sources exploited. For all the raw materials, field works and lab analysis (stereomicroscope observations, Scanning Electron Microscopy and µ-XRF analysis) have been set up. The results obtained show that several local primary and secondary deposits were exploited, located at few hundred meters from the site. Vein quartz was collected in secondary deposits at the base of the mount while rhyolite comes from secondary deposits located at about 2 km in a straight line from the site. Radiolarite was instead collected within deposits located at distance between 20 and 30 km from the Ciota Ciara cave giving the chance to formulate reliable hypothesis on the seasonal mobility of the Middle Palaeolithic hunter-gatherers of the Ciota Ciara cave.
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The entire lithic assemblage of the Ciota Ciara cave has been considered for the study of the supply areas of lithic raw materials. It consists of 7046 lithic artefacts divided in four stratigraphic units as shown in Tab. 1. In all the archaeological layers, vein quartz is the main exploited raw material, followed by other stones attested in different proportions in each level (Tab. 1). The present work has been conducted in different phases and combining several approaches: petrographic characterization of the lithic raw materials, land surveys based on geological data, comparison between the samples collected and the archaeological materials achieved through geochemical analysis (e.g. Aubry et al., 2012; Fernandes et al., 2006; Gurova et al., 2016; Navazo et al., 2008; Nazaroff et al., 2013; Olivares et al., 2009; Spinapolice, 2012; Tarriño et al., 2015; Vallejo Rodríguez et al., 2017). The characterization of the raw materials has been carried out through a non-destructive methodology as not to damage the archaeological finds (e.g. Aubry et al., 2012; Barcelo, 1996; Bustillo et al., 2009; Navazo et al., 2008). Due to the different characteristics of the lithic raw materials involved, specific methodologies have been applied, in particular concerning vein quartz. For all the raw materials, stereomicroscope observations have been completed using a stereomicroscope in reflected light Optika SZ6745TR with magnification between 0.6x and 4.5x, equipped with an USB camera Moticam 2500 with a 5-megapixel resolution, a lens providing a further 2x magnification and a LED-72T light ring.