Ancient Greek oral traditions got geology right
In the first century AD, a Greek geographer and historian named Strabo noted that a peninsula just south of Athens called Piraeus had, at one time in the past, been an island.
It's unusual for landforms to change so quickly that humans can take notice, even over generations, so that's a pretty interesting claim. The idea pops up elsewhere in Athenian oral tradition, as well as in the etymology of the name itself ("peran" means "beyond" or "on the other side"), so a group of French and Greek geologists and archaeologists decided to put it to the test.
The group collected sediment cores near Piraeus to infer its paleogeography, and used carbon dating to put the events on a timeline. In the end, Strabo's story checks out. Around 8,000 years ago, Piraeus was a peninsula resembling its current configuration. By 6,000 years ago, continued sea level rise from the end of the last ice age had drowned Piraeus' connection to the mainland, making it a proper island.
Around 4,000 years ago, sediment deposited by the Cephissus and Korydallos rivers had made the region between Piraeus and the mainland into a shallow lagoon separated from the Mediterranean by sandy beach ridges. By the time the Athenian citystate was blossoming, all that sediment had built up a large freshwater marsh, and the Athenian leaders constructed walls to fortify the connection between Athens and Piraeus, which was the location of the city's harbours. The evidence shows that the lagoon was not filled in as part of the constructionthe freshwater marsh provided a sufficient land connection.
This all means that Strabo got it right, which is doubly impressive, considering that Piraeus couldn't properly have been called an island more recently than at least a couple thousand years earlier. The researchers provide a couple hypotheses to explain how he did it: either the Athenian oral tradition was simply so good that the knowledge had reliably been passed down all that time, or Strabo was such a skilled geographer that he deduced the fact himself by examining the topography and marshland around Piraeus (assisted, perhaps, by the meaning of the name).
Source: Ars Technica