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Item Type: Tesi di dottorato
Lingua: Italiano
Date: 30 March 2014
Number of Pages: 390
Institution: Università degli Studi di Napoli Federico II
Department: Scienze della Terra, dell'Ambiente e delle Risorse
Scuola di dottorato: Scienze della terra
Dottorato: Scienze della Terra
Ciclo di dottorato: 26
Coordinatore del Corso di dottorato:
Morhange, ChristopheUNSPECIFIED
Di Donato, ValentinoUNSPECIFIED
Date: 30 March 2014
Number of Pages: 390
Uncontrolled Keywords: Geoarcheologia; Porto Greco-Romano di Neapolis; Baia di Chiaia; Municipio;
Settori scientifico-disciplinari del MIUR: Area 04 - Scienze della terra > GEO/04 - Geografia fisica e geomorfologia
Date Deposited: 07 Apr 2014 15:50
Last Modified: 28 Jan 2015 09:45


The city of Naples (Italy) is densely inhabited and rich in history, the area having been exploited for human settlements since the 7th century BC (Fig.1). Hence examining its geomorphological and palaeoenvironmental history is no simple task. For the last 20 years, archaeological excavations during the construction of the Naples metro have offered the possibility to conduct in-depth geoarchaeological research in the city and initiate fruitful collaboration between the Department of Earth Sciences, Environment and Resources of the University of Naples, the Archaeological Heritage Office of Naples and Pompei, and CEREGE, University of Aix-Marseille. During these years, geoarchaeological studies have sought to clarify the palaeoenvironmental evolution of the coastline to the east (Irollo, 2005; Ruello, 2008; Allevato et al., 2009, 2010; Amato et al., 2009; Carsana et al., 2009) and west of Naples (Romano et al., 2013) during the last 5000 years. Research has also led to speculation about the history of the relative sea level and local ground movements during the last 5000 years (Cinque et al., 2011; Romano et al., 2013) for the area now covered by the modern city. Here we present an overview of the different techniques used and the relative contributions made in reconstructing both the mid-late Holocene landscape evolution of the coastal sector of Naples and the palaeoenvironmental changes which occurred in the recently discovered Graeco-Roman harbour between the Hellenistic period and Late Antiquity. In particular two coastal sectors of Naples are analyzed, called “Bay of Chiaia” and “Municipio” (Fig. 2). The research started by examining the detailed computerized maps (1:1000) available for the city. In order to elaborate a digital elevation model of the topography (DEM), the cartographic base was loaded into specific map management software (ArcGis 9.3). To begin DEM processing it was necessary to extract from the cartography only the elevation points and a few contour lines in order to create and organize a precise dataset. These data were integrated with others obtained from a photogrammetric survey (1:11500) performed during the 1990s commissioned by the Department for Postseismic Intervention in Campania and Basilicata. To obtain a correct DEM, the elevation points of man-made structures like roads and buildings were eliminated from the data input. The procedure chosen for the interpolation was ‘Topo to Raster’, an interpolation method specifically designed for the creation of hydrologically correct digital elevation models. This method uses an iterative finite difference interpolation technique. It is optimized to have the computational efficiency of local interpolation methods, such as inverse distance weighted (IDW) interpolation, without losing the surface continuity of global interpolation methods, such as Kriging and Spline. It is also the only ArcGIS interpolator specifically designed to work with contour inputs. Water is the primary erosive force determining the general shape of most landscapes. ‘Topo to Raster’ uses the knowledge of surfaces and imposes constraints on the interpolation process that results in a connected drainage structure and correct representation of ridges and streams. The obtained DEM was used as input data to obtain a contour map in countering with equidistance between the contour lines of 1m and a slope map. The morphological analysis carried out on DEM and on the topographic base obtained, combined with stratigraphic data from boreholes at various points in the city, was used to recognize and reconstruct the geomorphological setting and the palaeodrainage network in order to speculate about their origin and history. The bibliographic study of the archaeological finds and their relative location in the surrounding area gave the opportunity to obtain information about the evolution of both the topographic surface and the palaeomorphology. Each archaeological find was organized into a geoarchaeological dataset and accompanied by the geographic location in the UTM system, its description, elevation and literary source. Archaeological finds useful for palaeo-topographic reconstruction were plotted in specific geological sections in order to understand their relationship with palaeoenvironmental conditions. The rich and very detailed cartography from the many representations of the city at various periods in its history (i.e. Strozzi, 1473; Lafréry- Du Pérac, 1566; Baratta, 1629; Stopendael, 1663; Duke of Noja, 1775; Russo, 1815) was analysed in order to improve the reconstruction of the palaeodrainage network and the ancient morphologies (marine terraces, fault scarp etc.) deleted from the current very dense urban context. By this approach we were able to view the landscape changes connected with urban development in a time range between the Early Middle Ages and the Modern Era. The palaeoenvironmental reconstructions involved an intense and detailed phase of field surveys in the excavation areas (AM: Arco Mirelli dig, SP: San Pasquale dig; MN: Municipio dig) (Fig. 2). The latter were designed to investigate a large number of vertical sections in detail (scale 1:100/1:10). Sedimentary facies were defined by analyzing the external bedding and internal organization concerned with the properties of the clasts such as colour, dimension, degree of rounding, and with the properties of the sediments like sorting, presence or absence of sedimentary structures and global arrangement. Field surveys also helped define the relationship between the geological processes and human pressure in the palaeolandscape. Stratigraphic units were reconstructed and dated by means of their archaeological content. During the field surveys tephrostratigraphic analysis was also carried out. The pyroclastic deposits interbedded in the sequences were measured and described in order to assess their emplacement mechanism. Correlation of these with well-known tephra deposits from the two volcanic districts in proximity to Naples, the Phlegrean Fields and Vesuvius, was made on the basis of their lithology and mineralogy, providing other chronological constraints for the reconstructions. All field surveys were integrated with the palaeoenvironmental information derived from a large number of boreholes drilled in the coastal sector. To improve the palaeoenvironmental reconstructions obtained, laboratory techniques concerned with particle size, palaeontological (macro-microfauna) were conducted on stratigraphic logs. In particular, granulometric analysis was carried out by wet sieving in order to separate coarse, sand and fine (silt+clay) fractions. The results were plotted in vertical-depth diagrams in order to recognize the change in granulometric characteristics along the stratigraphic sequence and in triangular graphs to group sedimentological layers with the same granulometric characteristics. As regards palaeoenvironmental evolution in the area, macrofauna and microfauna (Ostracods) species were grouped according to their palaeoecological environment and plotted in vertical-depth diagrams of taxa distributions. Granulometric and biostratigraphic variables were treated by a statistical approach: for granulometric data, statistical parameters of Folk and Ward (1957) such as mean size, sorting, skewness and kurtosis were calculated in order to obtain precise information about transport capability and degree of sorting of the depositional means; biostratigraphic data were treated with compositional analysis techniques (PCA). In order to combine samples into homogeneous groups, cluster analysis techniques were used. Thanks to the contribution made by all these disciplines and techniques, we are able to offer insights into coastal changes between preprotohistoric times and the Modern Era, and shed light in particular on the actual location of the ancient harbour of Neapolis and its palaeoenvironmental evolution from its foundation to its filling. These results are represented by geological sections and by palaeogeographic scenarios reconstructed on the DEM illustrating the main geomorphological features and the shorelines positions for different temporal steps. Pre-protohistoric Age (Fig. 3) Bay of Chiaia: Throughout the prehistoric period, the Bay of Chiaia, in “Arco Mirelli” and “San Pasquale” digs is characterized by submerged beach environment, affected by sporadic alluvial episodes. It has been possible to show, for the period prehistoric, an high and rocky coast landscape, characterized by a backward paleofalesia with respect to the current coastline. At the end of the prehistoric period we see a paleoenvironmental change of Chiaia coastal sector, caused by the deposition of pyroclastic products of Agnano Monte Spina and Astroni Eruptions. Indeed, field evidences in the studied areas show an intertidal environment abrasion platform, corresponding to the pyroclastic products of Agnano Monte Spina and Astroni Eruptions. Such platform is then covered by the volcanic products of Pomici di Avellino Eruption. Municipio sector The maximum of the post-glacial sea level rise, along the east coast of Naples, extended from Piazza Municipio to Piazza Garibaldi, is well evidenced by the presence of transgressive coastal sediments that fill the torrential incisions onto Neapolitan Yellow Tuff substrate, immediately after its deposition. At the peak of the Versilian marine transgression (c.a. 5ka) the paleo geographical scenario shows an high coast morphology, along the edge of Pendino. The shore line corresponding to the Middle Holocene period describes a bay right in the east of Mount Echia, in the area actually occupied by the dig "MN". Greek -Roman Age (Fig. 4) Bay of Chiaia: The Greek-Roman period shows a progressive change in the coastal paleoenvironmental context, with respect to previous time. Referring to this period sees a submerged marine environment establishing both in ‘San Pasquale’ and ‘Arco Mirelli’ digs. During the First Imperial Age (1st century AD), foreshore deposits alternate with submerged marine environment ones, constituting a bar - troughs system. Like Pre-protohistoric Age, torrential contributions interrupt the fine sand sedimentation typical of submerged environment and produce erosion and strong reduction of the deposits thickness. During the late 1st century AD and throughout the Middle Late Empire, the marine deposition and the upstream contributions determines the progressive progradation of the shoreline and the growth of a narrow beach strip at the foot of the Pre-Protohistoric paleofalesia. Municipio sector During the Greek -Roman Age (late 4th century BC- 4th century AD) it shows better the bay of the Pre-protohistoric Age. The area became the site of an harbour basin, as documented by the discovery of an Augustan Age quay built in mortar and tuff (“pds Line 6” and “Mezzanino San Giacomo” excavation areas in “Municipio dig”), and piers and jetties with orientation perpendicular to the quay (Fig. 5). To the north of the quay (1st century AD), merchant shipwreck are also found (“pds Line 1” in “Municipio dig”). During this time, the ancient harbour basin is characterized by a partially submerged beach, partially sheltered only in its oriental portions, due to the presence of a very pronounced promontory consisting of Neapolitan Yellow Tuff. Field investigations conducted in the “pds Line 6- Municipio dig”, showed traces of anthropogenic origin on the surface of tuffaceous substrate of the ancient harbour, located under the Augustan quay. The seafloor sediments of Greek-Roman harbour basin, covers a time interval between the 4th century BC (Hellenistic period) and the end of the 4th century AD. These sediments consist of medium-coarse sand in the inner zones of the basin that become more silty sediments moving towards the open sea. The functionality of the ancient harbour basin is provided by dredging of the seafloor sediments occurred several times between the 4th century BC and the 1st century AD The significant presence of ceramics, glass, building blocks, pebbles ballast is a further confirmation that the bay in this area is used as trading port. The entire period of functionality of the harbor basin, is also characterized by the presence of infratidal marine species in the sediments, connected with the open sea. Therefore, the faunal information confirm the idea that the Greek-Roman Harbour in Neapolis was not an artificial closed area but, on the contrary, a structure westward protected by a natural promontory and inserted into the open sea dynamics towards NE. During the period between the 2nd century AD and the 4th century AD, there is an increase of the macro-faunal species. Probably, marine species find physico-chemical conditions more favorable than those of the 1st century AD, at the end of both dredging activity and the reshuffle of the volcanic deposits of the 79 AD Vesuvius eruption. From Late Antiquity to the Modern Age (Figg. 6, 7) Bay of Chiaia: The coastal landscape during Late Antiquity consists of a narrow emerged beach characterized by alluvial deposits that cause the gradual burial of paleofalesia and the progradation of the shoreline. In the digs of “Arco Mirelli” and “San Pasquale”, torrential and alluvial deposits of the 4th century AD, deposited in alluvial fans locally cut the beach shore Roman Age units. Probably they are related both to climatic factors and to poor maintenance of the slopes in association with periods of global economic and social crisis. The succession of Late Antiquity closes with an anthropogenic deposit origin at about -1 m slm. The absence of selection and the chaotic distribution of materials lead to interpret this deposit as the result of one or more subsequent stages of discharges and the use of the beach below as a special area of the wast dump. The long hiatus (High Medieval Age) in the stratigraphic sequence at the top of the succession of Late Antiquity, which observed in both digs, shows a period of stability of environment emerged along the coast. Furthermore, it appears to indicate the existence of a significant stasis in the processes of erosion of the slopes behind the bay. With regard to the Modern Age, the profile of the studied coast appears shaped by the developed urban context. Municipio sector: During the first half of the 5th century AD, important paleoecological and paleoenvironmental changes are observed. The significant increase in lagoon and muddy sand species accompanied by a decrease of the infralittoral environment species, is interpretable as an enclosure of the harbor basin and the formation of a lagoon. The latter is favored by the growth of parallel beach ridges at the entrance of the bay. Also, the textural composition of the sediments of the seafloor (characterized by a decrease in grain size), is probably associated to sedimentation processes typical of an environment more sheltered than the previous phases. During the second half of the 5th century AD and the beginning of the 6th century AD occurs the progressive burial and abandonment of harbour basin. The sediments that close the stratigraphic succession of Late Antiquity (second half of the 5th century AD-6th century AD) are very coarse and not selected. Torrential arrivals in the lagoon fill it completely. The evidence of a change in the intended use of the area is evidenced by the widespread presence of paleosoils of the 6th century AD on which they were found accommodations farm. The modest shoreline progradational trend during Late Antiquity will continue until the Modern Age. In the late Medieval poor drainage condition typical of a marshy environment occurs. With regard to the Modern Age, the profile of the studied coast appears shaped by both the developed urban context and the construction of two port basins identified as “Molo Grande” e “Molo Piccolo.


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