Late Holocene Evolution of the Lagoonal Harbour of the Punic Centre of Othoca (Western Sardinia, Mediterranean Sea)

Geophysical surveys and multiproxy analyses of sediment cores have been used to reconstruct the palaeoenvironmental evolution of the Santa Giusta coastal lagoon (SGL), along the western coast of Sardinia. This area served as a natural harbour mainly during the Punic and Roman Republican periods (6th–2nd century bc). The inlet of the SGL is connected to the adjacent mouth of the River Tirso and lies on the incised valley of an ancient tributary that once fed into the Tirso during the last sea-level lowstand. The SGL formed after the sea level rose following the LGM, resulting in the inundation of the incised valleys, which were subsequently filled with estuarine sediments. About 6000 years ago, the area that is now occupied by the mouth of the river and the SGL was protected by a sandy barrier enclosing an open lagoon. About 4500 years ago, the deposition of alluvial sediments marked the beginning of the progradation of the river mouth, leading to the gradual enclosure of the SGL. Before 2100 years ago, the SGL was a suitable location for a sheltered harbour, as evidenced by archaeological indicators, both pottery and wooden structures, found within the lagoon sediments. By this time, the progressive narrowing of the inlet had reduced the accessibility of the site from the sea and the harbour lost its functionality.