Geoarchaeological investigations in the coastal archeological site of Nora (southern Sardinia, western Mediterranean Sea)

Mediterranean coasts have represented great places for relations and exchanges among peoples, especially since the proto-historical periods. In the Mid to Late Holocene (e.g., last 8 millennia) the combined effects of the slowing of sea-level rise and the increase of sediment input caused by both climatic and anthropogenic factors triggered the development of large Mediterranean coastal plains. These plains, heavily colonized by civilizations of pre-historical and historical periods, represent a major archive to better elucidate the millennial man-environment interactions along the Mediterranean coastal landscapes. Here we present a geoarchaeological investigation carried out at the archeological site of Nora, a major Punic- Roman town placed in southern Sardinia (western Mediterranean Sea). The multiproxy analysis involved meiofauna (benthic foraminifers and ostracods) and palynological analysis performed on two new cores collected in the coastal lagoons surrounding the archeological site. Furthermore, we carried out a geomorphologic and petrographic study of a number of beachrocks (paleo-shorelines) found few meters below the present sea-level. The chronological frame, based on a new set of 16 radiocarbon dates, allowed to provide fresh insights into the coastal modification of the last 4.3 millennia BP. In particular, we performed a high-resolution reconstruction of the local relative sea-level changes, which did not exceed the 1.35 m in the last 3500 years, and we identified the palaeoenvironmental dynamics that affected the lagoon system. These data allowed reconstruct the shoreline evolution of the area during the main period of occupation of the archeological site (e.g., from the Nuragic to the late Roman periods). This has been compared with the high-resolution mapping of the archeological structures in order to reconstruct their relationship with the paleo-shoreline at the time of their functioning period. Furthermore, palynological data elucidated the millennial variability in the vegetation dynamics as well as the anthropic influence in the changes of vegetational cover during the different archeological periods.