The Solfatara

 

High jets of boiling mud, sulphurous vapors, fractures of rocks, veins of mineral water, ground in constant motion. For the historian Strabone it was there the "Forum Vulcani", home of Vulcan, in that strange and extraordinary place not far from Puteoli, in the land formed and shaped by fire, the Campi Flegrei. Already from a distance, an unmistakable smell of rotten eggs signaled it, which justified the definition of “sulpha”, land of sulfur: the Solfatara. The most famous and fascinating of the many Phlegraean volcanoes, an object of particular interest since ancient times and frequented in the most diverse eras, despite the not rare danger of its phenomena.

The Solfatara is about four thousand years old. It dates back to the third Phlegraean eruptive period and covers an area of ​​thirty-three hectares in the heart of the Phlegraean Fields, about three kilometers from Pozzuoli. It is a dormant but active volcano, the only one in the Phlegraean area that has produced a lava flow towards the sea. However, being active, for about eight centuries it has shown its vitality with important gaseous emissions, a fundamental relief valve of the pressure exerted by the underground magma. The crater has an elliptical shape with a diameter of about seven hundred meters and a perimeter of over two kilometers. The belt that surrounds it reaches its maximum height south, with the 199 meters of the lava dome of Mount Olibano.

For millennia the Solfatara was also a precious mine, due to the variety and particularity of the minerals found there. Plinio the Younger defined that site "fontes leucogei", referring to the whitish color of its waters. Kaolin or bianchetto, used as stucco already in Roman times, was extracted there. Activity continued intensively also in the Middle Ages and after, so much so that in the second half of the 17th century a factory was even set up to extract various minerals, including sulfur and alum.

Over time, the appeal of the medicinal properties attributed to the thermo-mineral waters, muds and stoves of the Solfatara has been even stronger. Already in the Middle Ages it was thought that the thermal waters in the crater were a panacea against female sterility and other pathologies. Over time, pools were created to immerse oneself in, then swallowed up by the transformations of the caldera and also a well for drawing thermal water. In two natural caves, specially covered with bricks, the Ancient Stoves, the therapeutic properties of their volcanic vapors were exploited, at high temperatures, so much so that they were called one Purgatory and the other Hell. And the natural mud offered mud for treatments widely used in the era of the Grand Tour, when the Solfatara was one of the obligatory stops for travelers who reached Naples and Campania between the 18th and 19th centuries.

Among the attractions shown to visitors there was the Bocca Grande (big mouth), the most imposing of the many fumaroles, whose sulphurous vapors come out at 160 degrees. On the rocky walls surronding it, with reddish reflections due to the effect of the minerals present in the vapors, lives a species of invertebrates, the Seira Tongiorgii, identified in 1989, which lives only in that site. In the mud pit, on the other hand, there are colonies of Sulfolobus solfataricus bacteria, which manage to survive at temperatures above 90 degrees.

 

This last discovery is linked to research activities in the geological and naturalistic fields that find in the Solfatara an ideal place to develop. Once archived every mining and thermal activities in the mid 20th century, the Solfatara remains a unique natural scientific laboratory in the world, where the specific phenomena that characterize Phlegraean volcanism are monitored and investigated.