Poseidon's Sanctuary at Samikon—The Discovery of an Ancient Temple Through an Integrated Geophysical and Geoarchaeological Survey Approach for Lagoonal and Swampy Environments

Below the classical fortress of Samikon at the coast of the western Peloponnese, ancient writer Strabo mentioned a sanctuary of Poseidon which served as the centre of the religious association of the Triphylian cities. In this paper, we describe the discovery and investigation of a building structure by means of geophysical and geoarchaeological methods in a near coastal, lagoonal surrounding, posing questions about its connection to the sanctuary and about its abandonment. The paper emphasizes the uniqueness of the site, which on the one hand was clearly described by the ancient historian Strabo, thereby limiting its possible location. On the other hand, much of the area is overgrown, inaccessible and in a swampy lagoonal environment, hampering common geophysical prospection approaches. This leads to another question, namely, how the sanctuary can be located through prospection and which integrated methodologies are appropriate for such environments. The performance of the presented integrated approach is assessed using the discovered building as a case study. The architectural structure of the building visualized by geophysical prospection and subsequent archaeological excavations let us conclude that the building is a 28 m by 10 m Archaic sacred building. It was imaged using magnetic gradiometry with additional magnetization inversion, while its underlying stratigraphy was investigated by electromagnetic induction and electrical resistivity tomography, combined with geoarchaeological investigations. The results show that the temple was founded on sand embedded in lagoonal and swampy deposits being influenced by high‐energy flooding events. The presented approach, which combines rapid EMI mapping and depth sensing of stratigraphic features, shown here to be effective to appropriate depths in reasonable resolution in comparison with ERT, with coring and small‐scale near‐surface prospection, provides a feasible and promising approach for wetland prospection not only for the presented case study but for the wider coastal region.