Contribution of multiplexed electrical resistance and magnetic techniques to the archaeological investigations at Poros, Greece

The Sanctuary of Poseidon at Kalaureia is located on the island of Poros in the Saronic Gulf in Greece. Two Swedish archaeologists first carried out excavations at the site in 1894; in 1997 investigations were resumed by the Swedish Institute at Athens. Although there are traces of occupancy in the area by the early Bronze Age, the results so far attest to some activity in the very late Bronze Age (ca. 1100 BC); with a considerable proportion of the remains dating from the eighth century BC and the visible remains dating to the sixth to second centuries BC. A geophysical investigation was conducted at the site using both electrical resistance techniques and magnetic methods. A small area of 20 x 15 m at the southeast section of the site was surveyed with high-resolution multiplexed electrical resistance techniques in order to maximize the information content of the subsurface remains in both horizontal and vertical extent. The local vertical magnetic gradient of the Earth's magnetic field was measured using a flux gate gradiometer, and multiplexed electrical resistance techniques were applied in order to map the subsoil resistance at different depths. In addition, the whole area was investigated with a double twin probe configuration. Emphasis was given to the use of the multiplex electrical resistance technique with different configurations. A small grid to the southeast of the survey area was investigated with a twin probe configuration, recording the subsurface resistance at four increasing depths. Additionally, 0.5 m dipole-dipole and 0.5 m Wenner mapping configurations were performed. The above data were processed using a specifically developed processing package (GPP). The resistance instrument was also programmed in such away as to conduct parallel resistance tomographies along the x and y directions with a pole-pole array. Copyright (c) 2005 John Wiley & Sons, Ltd.