# Quaternary Evolution of Ischia: A Review of Volcanology and Geology
## 3 Results
### Review of the Marine Geology of Ischia  
Numerous are the studies performed on the marine geological setting of Ischia. Most of them are based on the data recorded during the scientific and technical activities carried out in the frame of the realization of the sheet n. 464 \"Isola di Ischia\" of the CARG project, both at the 1:50.000, 1:25.000 and 1:10.000 scales [55; 56].  
[PERSON] [60] has built the seismo-stratigraphic setting of the Late Quaternary to Holocene volcanic and sedimentary units and their correlation with the coastal units. New data have been exhibited on the Late Quaternary geologic development of the Ischia offshore through the interpretation of seismic profiles matched with the coastal geology of the comparable sectors. An elaborated geological work has been held out, centering on some aspects of the Ischia coastal part, seeing both high tuff sea cliffs (Succhivo, Punta dello Schiavo) and low sandy beaches (Spiaggia degli Inglesi, Cava dell'Isola). The first region is drafted by the Succhivo coastal cliff land, sited on the southern Ischia coastal belt westward of the S. Angelo headland; the second area is sited between the Ischia harbor and the beach of Spiaggia degli Inglesi; the third area is stationed in the western Ischia offshore towards the beach of Cava dell'Isola; the fourth sector is depicted by the tuff coastal cliff of Punta dello Schiavo, placed in the south-western Ischia offshore.  
The Quaternary deposits of Ischia have been addressed based on marine geological and sedimentological collection [61]. Marine geological maps at the 1:10.000 scale have been drawn, exhibiting that the sands are prevailing in the eastern Ischia offshore and the bioclastic sands happen at the top of relict volcanic edifices (Forio Bank, Ischia Bank) [61].  
Rhodolith deposits go on at the Ischia Bank and the genetically related parasitic vent and in the Ischia Channel, located between the Ischia and Procida islands [61].  
The bioclastic deposits of Ischia are represented by detritus facies derived by processes of in situ reworking of organogenetic materials on hard sea bottoms and are composed of coarse-to-middle-grained sands and gravels in a scarce peilitic matrix [61; 63]. Significant outcrops are on the inner shelf from 20 to 50 m, on the morphological saddles (Ischia Channel) and at the top of relict volcanic edifices, at both Ischia (Ischia and Forio Banks) and Procida (La Catena, Il Pertuso, Formiche di Vivara banks).  
[PERSON] et al. [64] have discussed the stratigraphic relationships between the volcanic and sedimentary units of the northern Ischia volcanic field, both onshore and offshore. The volcano-stratigraphic interpretation has allowed us to recognize the seismo-stratigraphic units of the northern Ischia offshore, showing acoustically transparent and chaotic seismic facies. The volcanic units, limited in extent, are inter-layered with eight seismic units, having continuous reflectors and corresponding with clastic units, which have been deposited during the inter-eruptive phases. During the Holocene, the eruptive activity of Ischia has been recorded in the area between the Ischia Castle, the Ischia harbor and Punta della Scrofa.  
The seismo-stratigraphic setting has also been reconstructed and is characterized by the occurrence of the volcanic basement, which is shallow over the whole area [54]. The acoustic basement is unconformably overlain by the volcaniclastic deposits and by the hemipelagic marine sediments [54]. The magnetic anomaly map has shown a complex pattern and a good correlation with the regional aeromagnetic data. In the western Ischia offshore, the magnetic anomaly has an amplitude of 1500 nT. This value is in agreement with the values observed in the volcanic edifices of the Campania region (Somma-Vesuvius, Roccamonfina, Ventotene).