The sites of Falassarna and Rithymna: An underwater geoarchaeological approach of Crete

Archaeologist-diver during the surveying of underwater archaeological remains.

Geoarchaeology, a branch of archaeology that oscillates between it and Geology, has left its mark in recent years on successful research bearing findings without which they would never have come to light. Aerial photographs, marine detection tools (side scan sonar) for mapping the seabed and Geopulse transmitters for examining the seismic activity of an area are just some such examples, which confirm not only the above relationship between the two fields,

but also the imperative use of science in the field.

Geological map depicting the Greek Arc (in bright blue the area of convergence of lithospheric plates).

The geoarchaeological research of many sites in the world and specifically in Greece based on this relationship, has brought interesting results with these methods – and not only – an example of which is the excavation of sites in tectonically active areas. When discussing the connection between geological phenomena and archaeological remains, archaeologists' minds automatically go to the cause-effect relationship. That is, that due to phenomena acting on the Earth's crust, and below it, on the mantle with pressure and heat forces at its center  such as tectonic movements of lithospheric plates, any architectural remains have been submerged over time.

Drawing showing the history of ground elevation.

Examples can be found everywhere in Greece and especially in the south, in the wider area covering the Peloponnese and up to Crete, as there is the convergence zone of the African lithospheric plate below that of Eurasia. This phenomenon already began to take shape millions of years ago, when lithospheric plates began to break away from Pangea and collide with each other from time to time gradually forming both continents and seas (Mediterranean, Caspian, etc.). And it is no coincidence that in front of the convergence front, both the Greek volcanic arc (volcanoes in Methana, Milos, Thira, Nisyros, etc.) and the shallow Mediterranean basin, basic features of the Greek Arc, are developing.

The port of ancient Falassarna.

The aforementioned convergence therefore brings about the intense seismic phenomena that affect Crete and the Peloponnese and are often heard in the news. Therefore, taking two examples of archaeological sites from the island, an attempt is made to investigate the relationship between the two sciences and to establish phenomena related to both seismicity and global sea level dynamics (eustaticity). Crete, due to its immediate proximity to the convergence area, presents a special geotectonic-geological feature, which may exist elsewhere on the planet, which is associated with subduction and at the same time elsewhere the emergence of archaeological sites. On the west coast, there is a general uplift, while on the corresponding eastern coasts, subduction occurs. This phenomenon results from the movement of two geotectonic blocks (parts of land that are cut off and separated from each other due to compressive forces) almost in its center (area starting from Rethymno in the north and reaching in the south in Matala).

An example of an elevated site of ancient remains in the west is the port of ancient Falasarna. The earthquake of 365 AD, the epicenter of which is located in the southwest of Crete, is responsible for this uplift and not by chance is adjacent to the tectonic convergence of continental plates. The remains of the classical and Hellenistic city of Falassarna are located inland, due to its 6.6 meters of elevation having a lifespan from the 4th to the 1st century BC, when it was destroyed by the Romans as a punishment for piracy that flourished in the city. The port was constructed artificially and had the form of a conthonos (characterization of the similar artificial port of Carthage), and essentially included an enclosed port connected to the sea with the help of a channel and four towers around it. Excavations and studies were carried out in the decades 1980-90 by the Ephorate of Underwater Antiquities.

Topographic plan of Rithymna with the shipyards and launching grates.

In Rethymno, as mentioned above, the general subduction of the eastern coast of Crete begins. The port of ancient Rithymna is one such example, as it is 0.2 meters from today's sea level. On the coast of the modern settlement and west of the Venetian fortress of Fortezza there are carved into the rock remains of shipyards and outdoor configurations, suitable for sliding boats, otherwise "slips" or grates. They were identified in 1972 by Flemming and Pirazzoli and in 2005 after research by the University of London Royal Holloway they were captured in three-dimensional form. The sinking of the port was caused due to the fact of the existence of a tectonic depression in Spili, Rethymno during the earthquake of 365 AD.

In conclusion, on the one hand, is that the remains of ancient ports are both indicators of the evolution of sea level rise, as well as a natural "historical record" for the history  of these sites. On the other hand, the harmony of the two sciences not only fills gaps that may exist in archaeological research, but also opens new horizons in the course of underwater archaeological excavations in the field, constituting the starting point for the enrichment of archaeologists' knowledge.

Text editing: Despina Nakaktsi

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