PALEOGEOGRAPHIES IN DELTA-ALLUVIAL PLAIN SETTINGS OF THREE PHOENICIAN HARBORS, PORTUGAL

Recent documentation that the seventh-century B.C. Phoenicians, merchant-seafarers of the Mediterranean basin, were exploring and settling as far west as Portugal, reveals that they were active along the coasts of the Atlantic and possibly seeking resources or trading into northern Europe. An interdisciplinary team of scientists has been assembled to investigate several harbor sites in Portugal, with an emphasis on locating buried Phoenician shipwrecks. Ships can prove to be veritable treasure chests of cultural and trade information, but the sites under investigation have undergone considerable geomorphic change and any Phoenician vessel must now lie buried within tidal-fluvial sediments.

Geologic coring and geophysics were employed to reconstruct the paleogeographies of three Phoenician sites in Portugal. The Abul site is situated along the Rio Sado estuary margin, the Castro Marim site is separated from the Rio Guadiana by two kilometers of tidal wetlands, and the Santa Olaia site is located on the alluvial plain of the Rio Mondego, over 15 km upstream of the mouth. Excavation has revealed a significant Phoenician presence at all three sites and it is presumed that they were harbors with immediate access to open-water sailing. This implies considerable late Holocene delta-alluvial plain progradation.

Cores, coupled with GPR and electrical resistivity data, reveal that marine to open estuarine conditions existed at the three sites, and that subsequent alluvial progradation has produced a >10 m thick late Holocene sequence of estuarine-delta-floodplain sediments. Radiocarbon dates from cores, coupled with the few published core data from the Rio Guadiana and a regional sea level curve, provide chronological control for paleogeographic reconstructions.

The identification of Phoenician-era shorelines serves as a predictive tool for locating possible harbors or anchorages, increasing the chance of locating buried Phoenician sea-going vessels. In some areas, the preservation potential for buried shipwrecks is high; however, significant burial depths may make recovery difficult and infeasible. On the other hand, deep burial may have preserved ships that otherwise would have been destroyed by modern practices used in the extensive saltpans and rice paddies of the region.