Geosources for ceramic production and communication pathways: the exchange network and the scale of chemical representative differences

The main objective of this study was to provide a methodological insight in the archaeometric field of ceramic provenance and technology, through the identification of the scale of representative differences in terms of clay composition. For this purpose, a total of 78 clay specimens-representative of the three types of Daunian clayey raw materials (Sub-Apennine clays, alluvial deposits and terraced alluvial deposits)- was collected and geo-chemically investigated, with the aim of determining up to which geographical scale, the exclusive application of geochemical analyses can provide reliable results for the reconstruction of clayey raw materials supply. For the Daunian territory, the scale has been identified with that of a 'riverine province', i.e. between the local and the regional extension of the north Apulian fluvial courses. In practice, the Sub-Apennine clays can be chemically distinguished into a northern group, including the Salsola, Vulgano, Celone and Lorenzo streams and a southern group, including the Carapelle stream and the Ofanto river. Moreover, the comparison between the geochemical composition of the clay samples and that of local ceramic productions (previously investigated) has shown that the Sub-Apennine clays were either used as received (Clay 1 group) or refined through decantation (Clay 2 group), before being shaped into fine wares or building materials; conversely, both the alluvial and the terraced alluvial deposits were used "as received" for the production of coarse wares. Furthermore, for the first time, the geospatial network analysis was further applied to the investigation of ancient raw materials exploitation. This analysis was performed in order to reach a reasonable reconstruction of both routes and travel times linking supply areas with production and distribution sites. Surprisingly, the results have shown that, at small distances, the transportation of clayey raw materials is not only reliable but rather highly likely, especially in those sites where Sub-Apennine clays are not readily available.