Sea level changes and past vegetation in the Punic period (5th–4th century BC): Archaeological, geomorphological and palaeobotanical indicators (South Sardinia – West Mediterranean Sea)

The ancient shorelines and main differences in the vegetational landscape of S Sardinia during the Punic period (5th–4th century BC) have been recognized by an interdisciplinary archaeological, paleobotanical and geomorphological approach. Sixteen trading amphoras and one olla of Punic manufacture brought to light during underwater exploration in Santa Gilla Lagoon (S Sardinia, W Mediterranean) provide data on relative sea level changes. The infilling mud of each retrieved amphora is representative of the ages lasting for about 200–300 years. The macro-archaebotanical contents document the use of seeds and fruits of Vitis, Sorbus, Ficus, Olea and Prunus during Punic trading and suggest the occurrence of agro-pastoral practices in the surrounding plains or the area behind the lagoon system. The palynological analysis documents the presence of holm and cork oak forests, a widespread Mediterranean forest with Juniper and Pinus, and a developed stagnant coastal system, and reveals a climate-induced past vegetation change that is likely to have been emphasized by anthropogenic pressure and agriculture activity during the 4th century BC. The GPS localization of the amphoras shows a distribution according to curved alignments that probably correspond to the shorelines (5th-4th century BC) at – 1.95 ± 10 m and −1.70 ± 10 m. Geomorphological data reveal a sea level rise of about 25 cm during a century, corresponding to 300 m of shoreline regression towards the alluvial plain. With these rapid processes of drowning of the coastal plain, the presence of Punic settlements along the lagoon borders documents the reorganization of commercial and economic activities. This shows the great adaptability of the ancient population to the sea level rise (SLR) and fast-flooding processes of the coastline in a lagoonal area vulnerable to subsidence phenomena.