Millstone coastal quarries of the Mediterranean: A new class of sealevel indicator

The coasts of Italy still preserve several remnants of coastal quarries built in antiquity, that now provideinsights into the intervening sea-level changes occurred during the last millennia. In this paper, we showand discuss a new class of sea level indicator consisting of millstones carved along the rocky coast ofsouthern Italy since 2500 BP, that are currently submerged. They were extracted from beachrocks,sandstones or similar sedimentary rocks, easier for carving by ancient carving tools. Our study focuses on10 coastal sites located at Capo d’Orlando, Avola, and Letojanni, in Sicily; Soverato, Tropea, and Capodell’Armi, in Calabria; Castellabate, Palinuro, and Scario, in Campania; and Polignano San Vito, in Apulia.Unfortunately, only limited archaeological information is available for these anthropic structures.Scario, one of these millstone quarries discussed here, has been dated through independent archaeologicalremains, allowing us to restrict the exploitation age to the end of XVII century. Present day elevationsof these coastal sites were obtained through geo-archaeological surveys calibrated using thenearest tidal stations, together with geomorphological and tectonic interpretations. Data were comparedagainst the latest sea level predictions based on glacio-hydro-isostatic models. Our results allow proposalof the age-range of these millstone quarries and to estimate the intervening relative sea level changessince the time when they were carved.