John Metcalfe was CityLab’s Bay Area bureau chief, covering climate change and the science of cities.
The waters off Zakynthos Island are ridden with columns and ghostly courtyards, but strangely no other signs of life.
Dive into the shallow waters off Greece’s Zakynthos Island and you’ll encounter a haunting sight: columns, pipes, pavement-like slabs, and other seeming remnants of a community long sunk in the sea.
For years, scientists believed these structures were part of a forgotten Hellenic civilization destroyed by powerful tidal waves. But a new study from the University of East Anglia and the University of Athens tells a different, no-less fantastic tale—that this “lost city” was built not by people, but by explosive gases and millions of hungry microorganisms.
Researchers came to this conclusion after barraging the highly geometric formations with lab tests revealing them to be of natural origin. They believe the structures began forming as early as 5 million years ago, when a hidden rupture in the seabed sent methane and other gases bubbling upward. Microbes living in underwater sediment devoured the carbon in these gases, instigating a chemical process that gave the mud the consistency of cement. Hard columns formed around the gas seeps, and marine creatures boring into the sediment gave rise to other strange “doughnut” shapes.
The fact the forms are arranged in linear fashion further suggest they sprouted from a clandestine faultline, the researchers say. Here’s more from an East Anglia press release:
Lead author Prof Julian Andrews, from UEA's School of Environmental Sciences, said: “The site was discovered by snorkelers and first thought to be an ancient city port, lost to the sea. There were what superficially looked like circular column bases, and paved floors. But mysteriously no other signs of life—such as pottery.…
“The disk and doughnut morphology, which looked a bit like circular column bases, is typical of mineralization at hydrocarbon seeps—seen both in modern seafloor and palaeo settings.”
It’s extremely rare for these fossil-like things to appear in shallow water, according to Andrews. To glimpse them typically requires a plunge into the frigid deep, often as far as thousands of feet down. But off Zakynthos they shimmer in green-tinged sunlight, as shown in these photos from the research team.