giovedì 8 agosto 2013

Naples, the Vesuvius and the Phlegraean Fields

The islands flegree
                              Naples, the Vesuvius and the Phlegraean Fields

The province of Naples is characterised by the three volcanic complexes of the Vesuvius, the Phlegraean Fields and the island of Ischia. Despite their closeness to each other, each of them has completely different characteristics as well as dissimilar form and extention.
The Vesuvius, the most famous of the three, easily recognisable by its distinctive shape and profile, gave rise to the most famous eruption in history. In 79 AD a plinian explosive eruption buried  the cities of Pompeii and Herculaneum thus providing us with a significant part of the world’s archaeological heritage. This was, however, only one of many eruptions the last of which took place in 1944.

The  island of Ischia is the upper part of a submarine volcano. About 55,000 years ago a violent explosive eruption took place known as the green tuff stone of Epomeo; the most important in terms of intensity and morphological transformation, its violence created a caldera which was invaded by the sea and later filled with the accumulation of piroclastic material that erupted from numerous eruptive vents on the island. 
Mount Epomeo is not a volcano but rather a sort of tuff stone column pushed up by the magma beneath. At an altitude of 787 metres, it is the highest point on the island. On the eastern side of its base are  numerous eruptive centres, the product of past effusive and explosive activity that has often taken place after long periods of quiescence. The last eruption was that of the Arso which took place in 1302 AD. Today, the island has important hydrothermal and fumarolic activity which is the manifestation of an uncalmed activity beneath the ground. A few years ago a loud rumble on the side of Forio caused alarm but it turned out to be only a vapour jet which had been suddenly released from beneath the hillside. 
Tuff stone is easily eroded by the elements – wind, sun and water. This explains the vast number of boulders balanced precariously on the steep slopes of Monte Epomeo. An earthquake could easily shake the ground and cause them to tumble down the mountain. Amazingly enough, one of the biggest of these did fall down in the past and was then chiselled and sculpted into a house which is now inhabited.
Monte Nuovo (1538)
The Phlegraean Fields are a particularly complex and extensive volcanic area with numerous eruptive centres. One of the most violent eruptions, the Campanian Ignimbrite, took place about 39,000 years ago while the Neapolitan Yellow Tuff Stone eruption took place 15,000 years ago. The most recent eruption was that of 1538 which in a week formed Monte Nuovo, destroying a village and transforming the landscape around it.
Classical iconography has always associated Naples with the Vesuvius. However the city’s real volcano is the Phlegraean Fields whose yellow tuff stone, the product of numerous eruptions over the centuries and millenia, lies beneath it. The construction of the city over the centuries has been characterised by the use of yellow tuff stone dug out from open air quarries, underground galleries and frequently even dug out in vertical shafts beneath the building that was then built with the extracted stone. This technique of stone extraction created large underground cavities which after being plastered served as cisterns for collecting rain water (see figure on the left). The subsoil is consequently riddled with cisterns and shafts which in the Greek and Roman period had already given rise to aqueducts with flowing water.
Cava sotterranea di tufo giallo appena scoperta
in località Piscinola (NA)

This incredible network of water canals, cisterns and wells which reached courtyards, and stairwells within houses needed maintenance from workers called the ‘pozzari’. To work in such narrow spaces they needed to be of small stature. They wore a light covering of sacking as protection from the cold and as protection for their clothes which would otherwise have been torn by scraping against the stone walls of the narrow shafts. It is likely that the figure of the ‘pozzaro’ gave rise to the legend of the ‘monaciello’ the ethereal child, generous if  at times also mischievous, so beloved by Neapolitans. The ‘monaciello’ however, is found not only in Neapolitan folk tradition but all along the Sorrento coast where there are also banks of tuff stone that have been perforated with shafts and  wells. And so we always leave a little piece of bread on the table after dinner for him…
The grey tuff stone of  Sorrento was produced by the fall of pyroclastic material from the Phlegraean Ignimbrite eruption (Archiflegreo). Surface lithoid banks are visible, above all, in cliffs overlooking the sea. Caves dug out over the centuries to extract stone for building and used as shelters or boat yards (monazeni) can also still be seen from the sea.
The figure above shows the "eye of the mountain", the initial, circular part that is dug out, widening as it descends, forming a bell shape. Stairs cut into the stone walls are also visible with signs of soot left by oil lamps.

Tratto dell'acquedotto romano sotterraneo che adduce a una
 cisterna  in zona Chiatamone (NA)
The photo on the left shows a branch of the aqueduct. In the foreground the base of the water canal in the shape of an upside down rectangle is plastered to protect it from  free flowing water (tuff stone is not impermeable) From canal to canal and cistern to cistern, the water network served the entire city. During the Greek and Roman periods the aqueduct, known as the Bolla, was second longest only to that of ancient Carthage. 
In 1629 Don Cesare Carmignano, assistant to the engineer Alessandro Ciminello, designed the enlargement of the aqueduct, by now inadequate to satisfy the increasing needs of the city. He provided it with new waters extracted from Sant'Agata dei Goti in the Benevento area. Known as the Carmignano after its planner, it remained in use until 1885 after which it was closed up following the numerous epidemies that hit the city.
The tuff stone, literally showered on the city by explosive volcanic eruptions together with lapilli and pozzolana were to be irreplaceable building materials while the incomparably fertile soils still provide nourishment for precious vines, fruit trees and tomatoes. Tuff stone has been transformed into tombs, cisterns, temples, castles, cathedrals and aqueducts. It has served to build city walls and fortifications. In the Second World War the subsoil of Naples was used for air raid shelters which saved the lives of hundreds of people.
The salubriousness of the Phlegraean Fields and the fertility of its soil still make it, together with the Bay of Naples a desirable destination for a cultured tourism that wishes to relive the splendours of Roman civilisation.

Neapolitans live out a strange relationship with their volcanoes, debateable and illogical, but also romantic and fatalistic. A bond that today is particularly difficult, given the excessive increase in population that instead of proliferating far from eruptive vents has created a demographic stranglehold around them. Like living in front of a cannon barrel; safety will depend on the length of the fuse and how early on we will be able to see the spark!

Translation: by Lisa Norall