Liuzza, Viviana
(2014)
RICOSTRUZIONE PALEOGEOGRAFICA E
PALEOAMBIENTALE DELLA CITTA’ DI NAPOLI:
UN’INDAGINE GEOARCHEOLOGICA.
[Tesi di dottorato]
| Tipologia del documento: |
Tesi di dottorato
|
| Lingua: |
Italiano |
| Titolo: |
RICOSTRUZIONE PALEOGEOGRAFICA E
PALEOAMBIENTALE DELLA CITTA’ DI NAPOLI:
UN’INDAGINE GEOARCHEOLOGICA |
| Autori: |
| Autore | Email |
|---|
| Liuzza, Viviana | liuzzaviviana@libero.it |
|
| Data: |
30 Marzo 2014 |
| Numero di pagine: |
390 |
| Istituzione: |
Università degli Studi di Napoli Federico II |
| Dipartimento: |
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: |
| nome | email |
|---|
| Boni, Maria | boni@unina.it |
|
| Tutor: |
| nome | email |
|---|
| Romano, Paola | [non definito] | | Morhange, Christophe | [non definito] | | Di Donato, Valentino | [non definito] |
|
| Data: |
30 Marzo 2014 |
| Numero di pagine: |
390 |
| Parole chiave: |
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 |
[error in script]
[error in script]
| Depositato il: |
07 Apr 2014 15:50 |
| Ultima modifica: |
28 Gen 2015 09:45 |
| URI: |
http://www.fedoa.unina.it/id/eprint/9801 |
Abstract
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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