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Image source: Scrope, George Poulett (1797-1876). Memoir on the geology of central France; including the volcanic formations of Auvergne, the Velay, and the Vivarais. London: Printed for Longman, Rees, Orme, Brown, and Green, 1827

Vulcan's Forge and Fingal's Cave

Volcanoes, Basalt, and the Discovery of Geological Time

Julia Springs From the Sea, 1835

Prévost, Louis-Constant (1787-1856). "Notes sur l’ile Julia, pour servir a l’histoire de la formation des montagnes volcaniques." Mémoires del la Société Géologique de France, 1835, 2:91-124.

In 1831 the Mediterranean south of Sicily began to boil and bubble, and before long a volcanic island appeared, in full eruption. The British spotted it first, and named it Graham Island. The French were not far behind, and gave the island a separate christening, as l’ile Julia. The volcano continued to spew forth ash and cinders through the late summer and early fall. One of the French observers was Louis-Constant Prévost, and he used the occasion to argue against the so-called ‘craters-of-elevation’ theory that was then advocated by many geologists. That theory argued that most of the elevation of a volcano was caused by a swelling of the land beneath it. Prévost pointed out that there was no swelling beneath Julia; rather, the volcano had raised itself from the sea-floor by ejecting rocks and cinders.

Prevost’s plate of Julia in full ferment makes a dramatic closing illustration for our exhibit, and it also suggests that, when it comes to volcanoes, the earth is still full of surprises.

Dean 1980, “Graham Island;” Rudwick, M.J.S., “Prevost, Louis-Constant,” in DSB 11:133-134.

View of Julia Island on September 1831. Image source: Prévost, Louis-Constant. "Notes sur l’ile Julia, pour servir a l’histoire de la formation des montagnes volcaniques." Mémoires del la Société Géologique de France, vol. 2, 1835, pl. 7.

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