Seafaring megaliths: A geoarchaeological approach to the Matarrubilla giant stone basin at Valencina (Spain)

A broad multidisciplinary approach is deployed to study an exceptional megalithic feature: the stone basin that presides over the chamber of the Matarrubilla tholos, part of the Valencina Copper Age mega-site (Sevilla, Spain). The study, including geoarchaeological characterisation and sourcing of the stone, traceological analysis of its surfaces based on photogrammetry and morphometrics, digital image analysis as well as OSL dating, leads to a number of substantial findings of great relevance to understand the significance of this stone basin, the only of its kind documented to this date in the Iberian Peninsula, with parallels only in Ireland and Malta. Among the most relevant conclusions, it is worth noting the fact that the gypsiferous cataclasite block the basin was made of was brought from the other side of the marine bay that five thousand years ago extended across the south-east of Valencina, this is the first evidence of waterborne transport of a megalithic stone in the Iberian Peninsula. In addition, the basin appears to have been put where it stands today sometime in the first half of the 4th millennium BC, long before any tholoi were built at Valencina, which suggest a prior history of still poorly documented monumentality at this mega-site.