'Ancient city' in bottom of the sea, not man made: study

Researchers, after fully studying the area, now have determined that the odd structures are not the remnants of a lost city but are actually the result of a natural geological phenomenon that took place roughly 5 million years ago, during the Pliocene era.

According to a study conducted by a joint team of researchers from the University of East Anglia in the UK and the University of Athens in Greece, the formations, which at first glance looked a lot like the bases of marble columns and other structures, actually formed when bacteria started to feast on methane gas as it leaked through the seafloor.

The bacteria over time caused a chain reaction that led to the cementation of sediment in the form of the discs seem out of place in nature on the ocean floor.

“It’s not particularly common, but it’s not something we haven’t seen or experienced before,” team leader Julian Andrews, from the University of East Anglia said. “It is however quite rare to find something like this in shallow waters.”

“This kind of thing tends to happen where you get significant amounts of methane seeping from oil reservoirs beneath the seabed, similar to a site I worked on in Scotland back in the 1980s,” Andrews continued.

The site was originally studied by the Ephorate of Underwater Antiquities of Greece – a government-run organisation that oversees many underwater archaeological digs in and around Greece. They ran preliminary mineralogical analyses, but weren’t able to determine how the structures came about.

This led to the formation of the team, which continued to analyse the mineral composition using microscopy, X-ray, and stable isotope techniques, allowing them to eventually come to their conclusion.

“We investigated the site, which is between 2 and 5 metres under water, and found that it is actually a natural geologically occurring phenomenon,” Andrews said in a statement.

The team’s results were published in the Marine and Petroleum Geology.