ATHENS (National Geographic) -- Since few detailed descriptions of Xerxes Canal (except those from Herodotus) have survived to the modern age, the idea prevailed that his claim was an exaggeration or an out-right invention. The mystery of the canal’s existence lingered for millennia. In the 19th century, interest blossomed in ascertaining whether traces of Xerxes’ canal could be found. Marie-Gabriel-Florent-Auguste de Choiseul-Gouffier (1752-1817) was a French count who served as ambassador to the Ottoman Empire. Passionate about ancient Greek history, he traveled the Aegean Sea aboard a frigate and in 1809 published the second volume of his chronicle Picturesque Journey through Greece, in which he argues that a canal had once existed, cutting straight through the Mount Athos Peninsula. He even drew up a plan showing the measurements and sections in accordance with Herodotus’ account. The romantic tone of his travelogue, however, and the absence of any rigorous scientific method led to his claims being dismissed.
In 1847, the Royal Geographical Society of London published topographical studies carried out by the sailor and geologist Thomas Spratt. These scientific findings did seem to corroborate the existence of the canal as described by Herodotus. What had seemed a typically tall tale was now gaining plausibility, but it would not be until the end of the 20th century that actual proof of the canal would begin to come to light.
In 1809, the French diplomat and traveler Count Choiseul-Gouffier explored the northern Aegean and argued for the existence of the Xerxes Canal.
From 1991 to 2001, a multidisciplinary team of British and Greek geophysicists, topographers, and archaeologists worked extensively on the site. It was a major collaboration involving the National Observatory of Athens, the British School of Athens, and universities in Leeds and Glasgow in the UK and Patras and Thessaloniki in Greece. Benedikt Isserlin, from the University of Leeds, and later Richard Jones, from the University of Glasgow, directed the decade-long project.
On the Isthmus of Corinth, the spit of land that links the Peloponnese Peninsula to the mainland, researchers have uncovered evidence of boats supported on wooden cylinders or wheeled platforms, which would have been dragged by slaves or animals along a stone causeway from one coast to the other. Isserlin wanted to first check whether such a causeway existed on the Mount Athos Peninsula and consider whether it could explain how Xerxes’ fleet had made the crossing. When no evidence of such a causeway came to light, the team went ahead with geophysical tests to see if they could locate a canal.
Exciting initial results showed there had indeed been some kind of ancient excavation in the middle of the peninsula, about 50 feet above sea level and some 65 feet deep. Taking into account that the sea level of the Mediterranean has risen more than three feet in the last 2,500 years, the team calculated that the depth of the seawater in the channel would then have been about 10 feet. They drilled nine boreholes, which allowed them to analyze the layers of the sub-soil. In the upper section (about 30 feet down), they found several ancient layers of silt. Then came a vital clue below that: a dense bed of reddish solidified sand extending for just over a mile. Here were the canal’s foundations—a wide, solid base.