An evaluation of the prospective archaeo-cultural heritage of the Northern Romanian littoral zone

Large displacements of the Western Black Sea coastline have been encountered during the Late Pleistocene and Holocene due to the Danube Delta’s lobs evolution in time which gradually restricted and finally closed the former Danube Estuary and Halmyris Bay. The notable consequences of this processes were the change of the number and position of the Danube River’s branches discharging mouths and related human activities such as: habitation, navigation, trade, etc. According to ancient historians (e.g. Herodotus in the 5^th Century BC, Polybius in the 2^nd Century BC, Strabo in the 1^st Century BC, Pliny the Elder in the 1^st Century AD, Ptolemy in the 2^nd Century AD and others), at that time, the Istros River (the ancient name of the Danube River) discharged its waters into the Black Sea through five to seven mouths (branches), among which the most important was the Hieron Stoma (Holly Mouth), identified today as being the Sfântu Gheorghe branch of the Danube.
   The combined result of the coastal zone subsidence (estimated amplitude of -2 to -4 mm/y) and the accumulative sedimentary regime within the Danube Delta area place the prospective cultural layer corresponding to late Prehistory – Early Antiquity at a burial depth that now exceeds 4-5 m, the only feasible way to investigate its extension being provided by geophysics. The applicability of the geophysical methods is also very closely linked to the ability of ancient human beings to modify, through their past activities, the habitation environment by generating local petrophysical contrasts. Such contrasts of physical properties (density, magnetic susceptibility, conductivity, etc.), all of anthropogenic origin, on which existence beneath the earth surface all geophysical investigation methods rely on, were only generated when the ancient inhabitants started to use the fire in increasingly larger scale, to excavate, to build (especially when using materials of allochthon origin) and, never the less, to use metallic tools and weapons. According to information gathered on the archaeological sites excavated on the adjacent Northern Dobruja, all these steps toward a better geophysical discoverability have been concluded since Early Bronze Age (3^rd Millennium BC). The deep burial of the past cultural layers, set close to the sea level in ancient time, could explain the lack of success of all archaeological works carried out during the last decades toward the discovery of the Histria’s and Argamum’s ancient harbors.
   The present position of the inhabited areas suggests the ancient ones were also located along the paleo-branches of the Danube and in the vicinity of the shoreline, at a safe distance from the effects of sea storms. Therefore, the most promising areas in this regard should be of course located in the close vicinity of the Sfântu Gheorghe branch’s paleo-banks, the most important distributor of the Danube River in Ancient times. Here, on several points located on the littoral sector confined by the present day Sfântu Gheorghe and Sulina branches’ mouths, the sea waves bring on the beach pottery remains originating from undiscovered yet antique wrecks caught in the relict beach ridge system and dug out by the intense erosion that presently deepens the seabed by 0.25 – 0.5 m/y.
   The possibility that the beach ridges system was born until approximately 500 years AD in the southernmost part of the Danube Delta, that gradually closed the former Halmyris Bay, partly covered today by Sinoie Lagoon and marine shallow waters, to host remains of fortified points and mostly wrecks of the ancient ships connecting Histria and Argamum fortresses with other harbours of the Black and Mediterranean Sea, must be considered. Numerous fragments of pottery brought today by waves on the beach south of Gura Portiţa could be reworked from the erosion submerged beach ridges and clearly sustain this hypothesis. This entire prospective archaeological load, with ages ranging from 8^th Century BC to 5^th Century AD, contained by the Împuţita - Câşla Vădanei and Coşna - Vadu littoral sectors, supposed to be represented mainly by wrecks of ancient ships, are in an imminent threat of being washed out by the intense erosion that now affects the shoreline as well as the adjacent seabed.