Magnetometric and electrometric investigations in the Beroe submerged archaeologic site

Abstract

In ancient times, Dobrogea was known as Schythia Minor or Mikra Skythia. In the Ist century BC, the respective territory was under the influence of the Pontic kingdom of Mithridate the VIth Eupator. From 28 BC it was integrated in the Roman province of Moesia Inferior by Emperor Augustus. Most Roman-Byzantine fortresses have been established by the Romans on the site of former Getic settlements: Tropaeum Traiani, Capidava, Carsium, Beroe, Troesmis, Arrubium, Dinogetia, Noviodunum, Ibida, Durostorum. The Roman-Byzantine fortress of Beroe-Ostrov grew around the Roman castrum of Beroe, where the Vth Legion was stationed in the Ist and IInd centuries. One can find here the partially unearthed ruins of a Roman and Byzantine fortress, dating back to the Ist-VIth and Xth-XIIth centuries, and nearby, those of a Paleo- Christian basilica, dating back to the Vth-VIth centuries. The latter is situated aside from the former cemetery, which has been used between the Ist -XIIth centuries. As a result of conflicts between the Dacians of Dobrogea (the Comati) and the Romans, the fortress was destroyed, and was re-inhabited once the Byzantines returned to the Lower Danube, under Emperor Ioan Tzimiskes. The Roman and Byzantine fortress from Beroe is located 3 km to the South of Ostrov village, in North Dobroudja, the north side of Moesia Inferior province. We carried out magnetometric and electrometric measurements in the Beroe archaeological site, located in the Dobrogea region of Romania. We analyzed the results to see if we could find the orientation of the walls or any other evidence of a former human presence within a limited area submerged beneath the Danube River. We showed the estimated depth of the site and the possible orientation of a wall. The geophysical data was acquired on the water (Danube River) within the submerged zone using marine equipment designed for that purpose (G822 device with cesium) with a gradient array and AGI ministing electrometer with 100 m length. The area of investigation was 100 by 50 meters, and it was located in the NE part of the site, having a grid density of 10 by 10 meters. The data we obtained in this study indicates the possible presence of submerged artefacts. Magnetic susceptibility measurements indicate a possible magnetic contrast between the regional geological background (local limestone rocks used in the construction of the fortress walls, mortar, etc.), characterized by low, sometimes even diamagnetic magnetic properties and artifacts such as bricks, backed (fired) adobe, ceramic fragments, showing relatively high magnetic susceptibilities.