For a lost Atlantis: the research of Helike

From its foundation, the city of Helike, located on the northern coast of the Corinthian Bay, was the capital of the kingdom of Ion, which extended from Sicyon to the border with Elis and a pole of attraction for visitors and believers, as it was the site of the Panhellenic sanctuary of the Ionians dedicated to Poseidon of Helicon. With the collapse of the Mycenaean world, the Ionians, together with other Greek tribes, colonised the western coast of Minor Asia, but their relationship with Helike was not forgotten after centuries, as shown by the religious mission of the Ionians in 373 BC to ask for the drawings of the sanctuary or the statue of the god. According to legend, not only was their request not granted, but they were murdered by the inhabitants of Helike, a crime for which the city paid dearly as Poseidon unleashed his divine wrath, overwhelming it with a tidal wave.

Peloponnese with the northern coasts and ancient Helike.

Initially, a submarine survey was carried out in 1988, sonar equipment explored an area of 8 km2 east of Aegio, yielding geological data showing seismic activity, with no evidence of submerged settlement remains. A new survey was conducted between 1991 and 1996 on the coastal plain and the hills to the south, using modern scientific methods. As a result,  46 sample boreholes were drilled to a depth of 20 meters in the areas of Temeni and Rodia, near the present settlement of Helike, the samples of which confirmed the presence of terrestrial and marine environments and helped establish the absolute dating of the remains through the use of C14 (radiocarbon).

Building vestiges of classical times.

The first archaeological horizon (1-4 meters deep) is dated to the Roman period, in accordance with pottery findings, while the second one starts from the Classical and reaches the Mycenaean period (4-12 meters deep).  In 1995, in the modern settlement of Helike, architectural remains of a Roman building were excavated on a private property after drilling and magnetometer measurements, bringing to light findings of pottery, bone and bronze objects, lamps, bronze coins, marble finds and bioarchaeological remains, dating between the 3rd and 5th centuries AD.  

The destruction of Helike, and especially the classical phase of inhabiting, was caused by a combination of geological factors. The two main phenomena that affected the area were the earthquake of 373 BC (6,7 magnitude), which caused subsidence of the subsoil of the order of 1.1-1.3 meters, and the resulting tidal wave that covered the city. In general, the wider area of Corinth is characterised by the earthquakes that continue to beset the region to this day due to the existence of numerous faults.  The only one of the ancient coeval writers with the destruction who mentions the sinking of a city with the above characteristics is Plato, who narrates the sinking of the mythical city of Atlantis in his Socratic dialogue Timaeus or On Atlantis (25d). Therefore, we can assume that the destruction of Helike inspired the creation of the myth of Atlantis.

Subsequently, the alluvial deposits of the two rivers of the region Selinous (to the west) and Kerynites (to the east) covered the submerged remains. The formation of the landscape after the disaster of 373 BC changed notably in three stages, which we know about through historical accounts from writers and travellers of the period following the disaster. The first reference is made by Eratosthenes, whose testimony is preserved by Strabo, who visited the site 150 years after its sinking. He describes the statue of Poseidon rising out of the sea, causing awe among fishermen (Geographica 8.7.2). At this stage, the area of the submerged city and the sanctuary of Poseidon were covered with a lagoon formed by the earthquake's tidal wave, which was called 'poros' ('πόρος').  

Map with the geotectonic structure of the Corinthian Gulf and the faults.

Diodorus of Sicily (1st century BC) also mentions the fact that the earthquake occurred at night and that was decisive for the magnitude of the disaster, as the injured people had little chance of help (Bibliotheca Historica 15. 48). Houses were destroyed and people were caught off guard by the darkness and geological phenomena, leaving them no way to escape after a large wave crashed down upon them. Pausanias, writing five centuries after the disaster, describes the flood caused by the earthquake, noting that only the tops of the trees from the grove of the Sanctuary of Poseidon could be seen, and that ancient remains were visible, eroded by the water  (Korinthiaka 8.24. 6).

3D morpho-archaeological plan of the Helike delta, showing the location of the ancient city between the Helike (HF) and Aegio (AF) active faults. (P): statue of Poseidon, (F): fault.

This is the second phase of the landscape of Helike, during which, over the centuries, the area gradually began to be silted up by the deposits of the rivers, resulting in the expansion of the land south of the plain, while the rest of the seaward part remained covered by water. Today, the area of Helike has been completely annexed, and the submerged ancient remains are covered under the sedimentary deposits created by sedimentary material from adjacent rivers.

Proofreading: Despina Nakaktsi

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