A 16th Century Volcano Adventure: “The Marvelous Hills of Sulphur”
It’s early 1550, and a young Sir Thomas Hoby is traveling through a volcanic wonderland. Britain hasn’t had anything comparable to the Campanian coast of Italy for tens of millions of years. There are places where geothermally-heated water rises through fractures and faults, used by humans to treat various ailments for milennia, but nothing as raw and exciting as what he sees here.
Taking the highway to the town of Pozzuoli, he marvels at the medical baths (Sudatorii) on the shores of Lago di Agnano: “…they cause good digestion and resolve raw humors, they lighten the body and heal the inward parts, they dry up fistles and wounds, and are very good against gout.”* In an age when medicine is still far more of an art than a science, these medicinal baths fed by volcanic springs are often the best chance at relief for people suffering from poor health.
He is probably unaware that these wonderful Sudatorii are a mere remnant of a medical spa industry that had been booming less than twelve years before.
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Illustration of medicinal baths near Pozzuoli from Pierre d’Éboli’s “De Balneis Puteolanis.” Credit: Pierre d’Éboli XIIe siècle–XIIIe siècle – dessin anonyme (CC BY-SA 4.0)
His attention is captured by sights one will never see back home: “By the baths on the lake side is a sandy hill. At the bottom of it is a pit, not far into the hill, or very deep or wide. In it is a mark beyond which any living creature is unable to move, foams at the mouth, and falls to the ground immediately.” If one quickly removes the stricken creature from the pit and washes it in the lake, it revives. Sir Thomas saw this horrible but fascinating resurrection trick done with dogs, cats, frogs, and various other critters. It seems almost magical. The pit is volcanic, probably filled with carbon dioxide and other poisonous gasses.
The highway continues on past the ruins of a Roman villa and canal. Beyond are more volcanic wonders: “After this, we come to the marvelous hills of sulphur, upon which are sundry little holes that with great force cast out very hot smoke and some flames of brimstone.” These are fumaroles, which won’t be well understood by scientists for another few centuries.
A fumarole in the Solfatara, near Pozzuoli. Credit: Norbert Nagel (CC BY-SA 3.0)
More geothermal features abound as his journey continues. “On the side towards Pozzuoli, there is an open entry into a large place which is plain and surrounded by hills. On one side of this plain is a pool of boiling sulphur water, out of which arises a very dark and black smoke. It boils night and day, winter and summer. It seems to be round, but it enters farther under the hill than can be discerned.” If anything is thrown in, only part of it can be removed. This is likely a highly acidic pool.
“These hills burn on every side and cast into the air great smoke with a very rank savor of brimstone; when the wind blows that way, it can reach as far as Naples,” Sir Thomas reports. But the sulphuric stench and waters are well appreciated by the locals: “They consider the savor very healthy for those with rheum and colds. And the boiling sulphur water, they say, is good for soothing the joints, clarifying the eyes, healing stomach ailments, helping infertile women conceive, driving away fevers, and healing scabs.” The brimstone hills have plentiful benefits to offer, and the Bishop of Pozzuoli derives large yearly revenues from them.
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The Gulf of Pozzuoli by Jacob Philipp Hackert (1737-1807)
Sir Thomas is charmed by Pozzuoli, which lies just beyond the brimstone hills. It sits on a little hill of its own, and is nearly surrounded by the serene blue sea. Between it and Baia a few miles away, swallowed by the waters of the bay, ruins of a Roman bridge lie “wonderously decayed.” Surrounding Pozzuoli are “sundry houses of pleasure, with their delicious gardens and healthsome prospects: also diverse antiquities and many great ruins, as an ampitheater, and a place underground called the labrinto, for the multitude of chambers in it.”
One could linger here a long while, but Sir Thomas continues along the coastal road to Baia. Just beyond Pozzuoli is another gift of the volcanic landscape: “a spring of freshwater which arises with such force out of the ground, and so abundantly, that for all it is within the sea, it has no taste of the salt water.
“Keeping along by the sea side, we come to a place called Tripergole, where there is a hill covered with great sharp stones…” We have reached our remarkable destination, a new mountain just over 400 feet tall and broad enough to swallow an entire town. “This hill arose suddenly out of the plain, sandy ground on St. Michael’s Day in the year of our lord 1538 with such a terrible noise and such violence that it cast stones as far as Naples, not without the great terror of many a man. An abundance of ashes carried by the violence of the wind fell at St. Severino, which is 24 miles from Naples. This hill for a good space after burned in the top and cast further stones, but it has ceased burning of late days.”
This is Monte Nuovo, the most recent magmatic display of Campi Flegrei, which erupted from September 29 to October 6th, 1538. It’s so new the stones have barely had time to cool – and if we, unlike Sir Thomas, head for the beach at the base of the cone, we’ll discover a large patch of sand so hot that it couldn’t be handled over two centuries later. It’s stark, black, raw, in violent contrast to the lush greenery and restful blue waters surrounding it. Beneath it, Tripengole lies entombed, just another entry on the long list of towns, cities, and settlements swallowed by eruptions in one of the most dangerous inhabited regions on Earth.
A modern volcano that gives some idea of what Monte Nuovo might have looked like. Credit: Freesally
Remarkably, Monte Nuovo doesn’t mark the graves of many people. Despite what Sir Thomas Hoby was told, residents had plenty of warning to flee, as increasingly violent earthquakes shook the town in the days before a fissure split the earth. They didn’t know there was going to be a volcano, but they knew enough to evacuate. We know of no victims until a last large explosion killed twenty-four brave souls who had climbed the new mountain on October 6th. For a volcano emerging in the middle of a heavily populated area in the days before volcano monitoring, it was remarkably low on casualties.
Monte Nuovo is our gateway to Campania and our first stop on this tour of Mediterranean geology. We’ll see how its birth was preceded by a century of unrest. We’ll experience, through eyewitness accounts and subsequent scientific investigations, its remarkable eruption. We’ll examine its impact on the citizens and their medical spa industry. And we’ll see how this incredible little cinder cone is just one brief verse in an epic whose end is yet to be written.
ISS photo of Pozzuoli and the Campi Flegrei, annotated. Credit: NASA
*I’ve translated Hoby’s text from early modern English to the best of my ability. A few minor liberties were taken, but I hope to have stayed fairly faithful to his original meaning.
Featured Image: Monte Nuovo and Lake Lucrino. Credit: Denghiù (Public Domain)
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