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From out the azure main

What is a "submerged island"? How, if at all, does it differ from the sea bed? Ted Nield ponders the significance of a here today, gone tomorrow island - from the February issue of the Society's colour monthly, Geoscientist magazine.

I once heard a child ask his geologist father why the sea stopped at the beach. It’s one of those questions only children ask but which only geologists are likely to answer seriously. They will answer because they know that, on our planet’s mobile crust, the level of the sea relative to the land at any given time and place is a pretty insignificant fact. This is not a view much shared outside geology, however, and geologists didn’t always share it, either.

There is little more annoying to scientists than being questioned closely and repeatedly about insignificant things. No doubt this explains the exasperated tones of geophysicist Antonio Zichichi, (Ettore Majorano Centre, Erice) when asked (presumably for the 583rd time that day) about a mysterious volcanic island that (according to Reuters) was reappearing in the middle of a busy shipping lane off the shores of Sicily.

As in 1831, when this last happened, a diplomatic row was breaking over whose territory it would be. Did previous claims still hold? Could it be said to be the same island? Could it be pre-emptively claimed with an underwater plaque? (And while we are on the subject, who had smashed it?) And can territory be legally claimed at all, while it is still under the international briny?

As you might imagine, opinion was hot, strong, and diverse. And caught in the middle of it, geologists - the one group that simultaneously knew most, and cared least.

This speck of strategically important potential land is known to the British as the Graham Bank volcano (and to the Italians as Isola Ferdinandea, the French as L’Isle Julia, and various others as Nerita, Hotham, Corrao, and Sciacca). Professor Zichichi probably had his own name for it by the time he thundered to the Belgian newspaper Le Soir: "We are not interested in plaques!…It goes up and down because the Earth’s crust goes up and down and that’s that!" You can almost hear the phone slamming.

Enzo Boschi, (head of Italy’s Institute of Geophysics and Volcanology) seems to have re-started the current round of interest in Graham Bank in an interview with Reuters, the news agency, following reports of water disturbance in the area. Boschi said the Graham Bank volcano might erupt "in a few weeks or months. This quote quickly spread through the online media, resulting in a thoughtful feature by Rose George in The Independent on 26 September. The whole thing then went quiet for a month, erupting finally in other newspapers a month and a day later.

What reawakened the story yet again in November was the Italian Naval League. This official body suddenly demanded that Italy prevent perfidious Albion (or any other nation) from stealing their island again, like they tried to do in 1831. You see, the name we use for the seamount derives from Admiral Sir James Robert George Graham, First Lord of the Admiralty no less, who claimed the newly emerged island for Britain by planting a flag on it. However it was also claimed by France, Spain and of course the Kingdom of the Two Sicilies (Italy, as we know her today, didn’t exist then). The diplomatic furore only died when everyone realised that, while they had been fighting over sovereignty, the sea had solved the problem by eroding the island completely away.

Graham Bank seems to have been put on Earth to make fools out of men. As recently as 1987, US warplanes spotted it, thought it was a Libyan submarine, and dropped depths charges on it. And most recently, two surviving relatives of the Bourbon kings of the Two Sicilies (Ferdinand II being the Royal source of the Italian name for Graham Bank, Ferdinandea) commissioned divers to plant a pre-emptive plaque on the submerged reef, claiming it for Italy should it ever re-emerge. The Prince and Princess of Bourbon, who piquantly go by the names Charles and Camilla, clearly felt they had family ties to the place; but even they were not the prime movers.
That role was played by Domenico Macalusa, a surgeon by profession but also a voluntary "Inspector of Sicilian Cultural Riches" and amateur diver. He first became interested in Ferdinandea (as he of course calls it) in February 2000, when news of eruptions first broke. These reports were couched in terms of the reappearance of a lost corner of the (British) Empire, and feathers ruffled. Macalusa subsequently persuaded the Bourbons to commission the marble plaque (all 150kg of it), which he duly installed 20m under the wave, in March last year. (Mysteriously, the plaque was subsequently broken into 12 pieces by person or persons unknown…)

Most geologists would probably admit that alongside such intrigue, the geology of Graham Bank looks rather boring. Today, the scoriae surrounding the vent have been planed off and lie 30m deep, while a 20m-diameter plug rises centrally to a dangerous 8m below the wave. This dark rock contains phenocrysts of bytownitic plagioclase, forsteritic olivine and rare titano-augite, set in a dark brown mass of glass and pyroxene crystallites. In other words, it’s an alkali olivine Hawaiite basalt, high in sodium, largely uncontaminated by crustal material. Geologically, nothing to get too excited about.

In its rather jaded coverage of excitable press reports about Graham Bank, the web site Stromboli Online sniffed: "These days everything that has something to do with volcanoes or earthquakes in Italy makes it to the news…" But such haughty scientific disdain was not evident in 1831. Then, the island was greeted as a prodigy, and aroused great geological excitement. The French geologist and founder of the Société Géologique de France, Louis Constant Prévost, wrote a paper on it in the Mémoires, complete with lovely colour plates illustrating the island – which had long vanished by the time the paper came out in 1834/35. Charles Lyell, for whom the crust of the Earth going up and down was much more exciting than it is today for Prof. Zichichi, devoted six pages to it in the third (1834) edition of the Principles. But science has moved on.

Geologists might not view the emergence of volcanic islands with the childlike wonder they used to when their science was young. Geology is a culture, and cultures mature, just like people – gaining knowledge and wisdom, and becoming just a little blasé in the process. The public however, will always think it a wonder – just as children, looking at the shore in 2003, will ask much the same questions that children asked in 1831.

Perhaps the last word should go to Filippo D’Arpa, a journalist with Il Giornale di Sicilia, whose timely novel about the events of 1831 (The island that went away) was published last November. "It is a metaphor on the ridiculousness of power. This rock is worth nothing, it’s no use as a territorial possession, and yet the French and the Bourbons… nearly came to war [and] 160 years later, English and Italians are still fighting…"

* You can read more about Ferdinandea in Ted Nield's book Supercontinent - 10 billion years in the life of our planet, published by Granta books in October 2007

Further reading

Independent 26 September: The Island that time remembered. BBC Online 26 November 2002: Volcano may emerge from sea; Times 27 November p20; Italy stakes early claim to submerged island. Colantoni, P, del Monte, M., Gallignani, P, Zarudzki, E., 1975; Il Banco Graham; un vulcano recente del canale di Sicilia. Giornale di Geologi Bologna (2) XL., fasc. 1., pp 141-162. Prévost, M C., 1835; Notes sur l’ile Julia pour servir a l’histoire de la formation des montagnes volcaniques. Mem. Geol. Soc de France, T2, Mem. 5 pp91-124; Lyell, C., 1846, Principles of Geology, vol. 3 p145 et seq.