The Phlegraean Fields ( ; , from Ancient Greek 'to burn') is a large region of supervolcanic calderas situated to the west of Naples, Italy. It was declared a regional park in 2003. The area of the caldera consists of 24 craters and volcanic edifices; most of them lie under water. Hydrothermal activity can be observed at Lucrino, Agnano and the town of Pozzuoli. There are also effusive gaseous manifestations in the Solfatara crater, the mythological home of the Roman god of fire, Vulcan. This area is monitored by the Vesuvius Observatory. It is considered a supervolcano. The area also features bradyseismic phenomena, which are most evident at the Macellum of Pozzuoli (misidentified as a temple of Serapis): bands of boreholes left by marine molluscs on marble columns show that the level of the site in relation to sea level has varied. Geological phases Three geological phases or periods are recognised and distinguished. The First Phlegraean Period. It is thought that the eruption of the Archiflegreo volcano occurred about 39,280 ± 110 years (older estimate ~37,000 years) ago, erupting about of magma ( bulk volume) to produce the Campanian Ignimbrite eruption. Its Volcanic Explosivity Index (VEI) was 7. "The dating of the Campanian Ignimbrite Eruption (CI) to ~37,000 calendar years B.P. draws attention to the coincidence of this volcanic catastrophe and the suite of , Late Pleistocene biocultural changes that occurred within and outside the Mediterranean region. These included the Middle to Upper Paleolithic cultural transition and the replacement of Neanderthal populations by anatomically modern Homo sapiens, a subject of sustained debate. No less than 150 km3 of magma were extruded in this eruption (the CI eruption), traces of which can be detected in Greenland ice cores. As widespread discontinuities in archaeological sequences are observed at or after this eruption, a significant interference with ongoing human processes in Mediterranean Europe is hypothesized." It is possible that these eruptions drove Neanderthals to extinction and cleared the way for modern humans to thrive in Europe and Asia. The area is characterised by banks of piperno and pipernoid grey tuff at Camaldoli hill, as in the northern and western ridge of Mount Cumae; other referable deep products are those found at Monte di Procida, recognizable in the cliffs of its coast. The Second Phlegraean Period, between 35,000–10,500 years ago. This is characterized by the Neapolitan yellow tuff that is the remains of an