By Jonathan Amos
Science reporter, BBC News
A UK-led team is challenging cherished ideas on Greek mythology by proposing an alternative site for Ithaca.
The island was said to be the home of Odysseus, whose 10-year journey back from the Trojan War is chronicled in Homer's epic poem the Odyssey.
Most people think the modern-day Ionian island of Ithaki is the location.
But geologists are this week sinking a borehole on nearby Kefalonia in an attempt to test whether its western peninsula of Paliki is the real site.
The scientists hope to find evidence that the peninsula once stood proud, separated from Kefalonia by a narrow, navigable marine channel. It is only in the last 2,500-3,000 years - and after Homer's time - that the channel has been filled in, the team contends.
"We can't prove the story of the Odyssey is true, but we can test whether Homer got his geography right," said Edinburgh University geologist Professor John Underhill, who is supervising the drilling operation.
At issue are a few lines of hotly debated text, in which Homer describes Odysseus' native land.
He talks of low-lying terrain, furthest out to sea and facing dusk.
The team, which includes geologists, classicists and archaeologists, argues that modern-day Ithaki does not fit this description.
It is dominated by high ground and, being on the eastern side of the Ionian arc of islands, actually looks - if anywhere - towards "dawn and sun".
"This has always been a contentious issue since antiquity," said James Diggle, a professor of Greek and Latin and fellow of Queens' College, Cambridge.
"Many different candidates have been suggested and the general feeling has been that the island that has the same name now - Ithaki - must be Ithaca, but it simply doesn't square with all the geographical information we have about the original Ithaca.
"The suggestion we advocate, and are now testing with the geology, is a radically new one; involving as it does splitting the island of Kefalonia into two," he told BBC News.
The Paliki solution was first proposed in Robert Bittlestone's 2005 book, Odysseus Unbound: The Search for Homer's Ithaca. Paliki is certainly flatter than Ithaki, and the most westerly point in the Ionian arc.
But to prove its hypothesis, the team will have to show - at the very least - that the sea once flowed through a tight channel that is now the Thinia isthmus joining Paliki to the main part of Kefalonia.
On the face of it, this a tall order - literally: the highest point on the isthmus is some 180m above sea level.
Homer and his poems have been placed in the 8th Century BC
To suggest the Mycenaean landscape could have changed so radically in so short a time seems extraordinary, especially since modern seismic surveys in the area indicate the amount of uplift experienced by Kefalonia over the past 3,000-5,000 years is perhaps 6m at most.
The team's argument is that the channel has been covered by a colossal infall of rock from the surrounding hills, particularly those on the eastern side of the Thinia valley.
"The bedding planes all dip very steeply towards the valley, and they are natural planes along which landslip and rockfall can occur - and do, periodically," explained Professor Underhill.
"This happens in winter, never mind in the frequent earthquakes they experience there. There are very interesting Pathe news pictures taken after the devastating earthquake of 1953 which demonstrate that whole hillside degraded significantly; huge volumes of rock came off the slopes."
This week's investigations involve sinking a 100m-plus borehole at the southern end of the valley. If the Paliki solution stands up, it should find a loose aggregation of rock and debris through the core's entire length.
"If we hit hard rock, the theory will not fly," said Professor Underhill.
But assuming the borehole is successful, then the team will apply for funding to carry out a more extensive programme of drilling. Ground-penetrating radar, gravity and seismic surveys have already been conducted; carbon-14 and other dating techniques would need to be brought in to prove the infall occurred in the right timescale.
Archaeological investigations have put Troy in Turkey
The team is encouraged by the writings of the 1st-Century-BC Greek geographer Strabo, who mentions the existence of a channel many years after Homer is presumed to have lived in the Ionian region.
And, of course, this is by no means the first time that science has sought to match current features on the landscape with Homeric descriptions.
The city of Troy featured in the Iliad is now widely recognised to have been in north-western Turkey. A study of river sediments in the region would even seem to fit with aspects of the military campaign that Homer's story says eventually led to the destruction of the city.
If the existence of a Bronze Age channel on Kefalonia is proven, it is quite likely to set off anew heated arguments about specifics and meaning in the Odyssey.
And some will continue to contest Ithaca's location. Sarantis Symeonoglou is professor of art history and archaeology at Washington University in St Louis, US. He has spent years trying to tie locations on Ithaki to details in the poem.
"I have been digging [there] longer than anyone, since 1984. I already have solid evidence that the site of the city of Odysseus is where Homer says, on the saddle of Aetos, at modern (and ancient) Ithaca. The palace is in a terrible ruined condition, but identifiable! I found a corner of it," he told BBC News in an e-mail.
John Bennet, a professor of Aegean archaeology at Sheffield University, UK, commented that any new discovery of a channel should be viewed in a wider context.
"For the archaeological world, what is very interesting is the possibility that there has been major geographical, geomorphological change on the island of Kefalonia, which means the way people have lived on the island has changed significantly from the Bronze Age into the broadly Classical period.
"As a result of that there will be a new phase of general archaeological data that will benefit all of us."
I am Odysseus, Laertes' son, world-famed
For stratagems: my name has reached the heavens.
Bright Ithaca is my home: it has a mountain,
Leaf-quivering Neriton, far visible.
Around are many islands, close to each other,
Doulichion and Same and wooded Zacynthos.
Ithaca itself lies low, furthest to sea
Towards dusk; the rest, apart, face dawn and sun.
Odyssey 9, 19-26 (trans. James Diggle)