1,721,289 research outputs found
Gradiscutta di Varmo (prov. de Udine)
No full textBourdin Stéphane, Fontana Alessandro, Tasca Giovanni. Gradiscutta di Varmo (prov. de Udine). In: Mélanges de l'École française de Rome. Antiquité, tome 114, n°1. 2002. Antiquité. pp. 533-541
Alluvial Geomorphology in Italy
No full textMonographic issue of the Journal focused on the current researches about alluvial geomorphology in Italy. In the issue there is a review paper about the late-QUaternary evolution of the valleys of the Marche region and 5 papers of case studies along the Italian Peninsula, form the Po Plain to the Basilicata region
Acqua e civiltà nelle Terramare, la vasca votiva di Noceto
No full textRecensione del volume riguardante la straordinaria scoperta archeologica della vasca votiva del sito di Noceto (PR), in cui sono state compiute avanzate analisi di tipo stratigrafico e geoarcheologico per ricostruire il paleoambiente e il paleoclima presente durante la costruzione del manufatto
Carta dello spessore del sintema del Po, Foglio 107 "Portogruaro" della Carta Geologica d'Italia alla scala 1:50.000
No full textFoglio relativo alla cartografia del sottosuolo allegato alla Carta Geologica d'Italia alla scala 1:50.000 del Foglio 107 "Portogruaro". La carta rappresenta lo spessore dei depositi appartenenti al sintemadel Po, corrispondente ai sedimenti post-LGM (ultimi 17.000 anni) sia alluvionali che costiero-marini. Lo spessore è misurato in metri rispetto all'attuale superifice topografica o dal fondo marino. La mappa consente di evidenziare le profonde e larghe incisioni fluviali formate dal Tagliamento e dal Piave tra il tardoglaciale e l'Olocene iniziale e successivamente riempite dai sedimenti più recenti sia fluviali che lagunari e costieri
Evoluzione geomorfologica della bassa pianura friulana e sue relazioni con dinamiche insediative antiche
No full textThis is a research of alluvial geomorphology and
geoarchaeology that analyses the evolution of the
lower sector of the Friulian plain (NE Italy) since the
last 25 ka ca. The work recostructs the sequence of
the natural and anthropic events that stratified in time
and space and originated the base of the modern
landscape; the environmental constraints that forced
the settlement choices and the changes induced in the
area by human activity are highlighted.
A strong multidisciplinar approach was applied,
based on the correlation and integration of information
collected with geomorphological, geological and
archaeological investigations. Researches were carried
out at different scales, from remote sensing to
microscopic thin sections. Analyses of aerial pictures
and satellite images, covering the whole area, led to
identify most of the natural landforms (e.g. abandoned
river and lagoon channels) and the tracks of
ancient human activity (roads and field system divisions).
These data were crossed with a digital terrain
model allowing to detect areas of interest on which
field survey has been later carried out. Field activity
consisted of the description of stratigraphic sections
along the slope of canals and ditches, in road, pipe
and building yard and in archaeological excavations;
a number of bore-holes were performed, mainly with
a hand gouge and partly with mechanical gouges.
Many sediment samples were collected and some of
them submitted to radiocarbon dating.
The low Friulian plain is characterized by the presence
of Tagliamento river and a number of groundwater-
fed rivers. These are fed by many springs,
arrangend in a belt that separates the “high” plain
from the “low”; the first one is gravelly and is characterized
by the lack of a surface drainage, whereas
the second one mainly consists of clayey-silt sediments
and is abundant in surface water. The Friulian
plain is formed by alluvial megafans that are characterized
by a telescopic geometry due to the existence
of aggrading and erosive phases, which are mainly
related to climate changes and eustasy.
The main phase of sedimentation occurred during the
acme of the Last Glacial Maximum (LGM), 25-18 ka
BC, when the glacier hosted in the mountain catchment
reached the plain and its melting water fed the
megafans of Tagliamento, Corno, Cormor and Torre
rivers. Deposition occurred over the whole surface of
the plain with a thickness of 20-30 m. Gravel deposition stopped about 30 km far from megafan apex,
leading to the formation of the gravelly high plain;
only sands or fine sediments reached the distal sectors.
During glacier decaying (18-15.5 ka BC) the
rivers fed by glacier entrenched the apex of their
megafan, but limited aggradation continued in the
low plain, originating a telescopic lobe with narrow
gravelly-sandy fluvial ridges.
In the post-LGM, since 15.5 ka BC, sedimentation
stopped abruptly leading Cormor and Corno megafans
to deactivate and inducing the formation of
several incisions also in the distal portion of the
Tagliamento megafan; these “valleys” (15-25 m
deep, 0.5-1.5 km wide) confined the sedimentary
flux which by-passed the plain and could transport
coarse gravel up to the present coast. Thus a period of
non-deposition affected the whole Friulian plain until
6-5 ka BC, when the onset of the marine high stand
triggered lagoon and delta formation. Anew aggradation
phase affected the coastal portion, while an erosive
trend is recognizable in the other sectors of the
Tagliamento megafan up to 2-1.5 ka BC. At that time
widespread aggradation started and the pre-existing
incisions silted up completely. Fluvial ridges formation
characterized the lower 30 km of megafan in the
last 3 ka and gravel transport stopped about 20 km
upstream from the coast.
The cross correlation of the stratigraphic, archaeological
and geochronological datings allowed to build a
robust chronological framework of the post-LGM
geomorphological phases. A reliable hypothesis
about the different directions followed by
Tagliamento river and their period of activity in the
post-LGM is presented.
Large surfaces of the Friulian Plain date to the LGM
and allow a good visibility of the archaeological
sites; whatever, the marine transgression submerged
large sectors, previously available for settlement.
In the area the first evidence of human presence
corresponds to few artifacts dating to Final
Epigravettian (11.500-9500 BC) and Mesolithic, but
only in the ancient Neolithic (5500-4800 BC) a first
period of widspread peopling occurred, coinciding
with lagoon formation and warm climate. Many villages
of this phase are known and they were totally
found on top of cataglacial fluvial ridges, demonstrating
that natural soil fertility and topography had
strongly influenced the position of the settlements.
Human peopling strongly decreased since the middle
Neolithic and it was almost dissolved until the
ancient Bronze Age, probably reflecting also a nomadic
or semi-nomadic living style. Part of this period
coincides with a colder climate and a very high river
activity developed around 2800-2400 BC.
An important peopling stage is represented by the
recent Bronze Age (1350-1150 BC) in which a well
developed territorial system existed; it was characterized
by some major sites, sometimes defended with
rampants (castellieri) or wooden fences, and controlled
several minor settlements. Complex irrigation
systems and connections between sites existed. At
the transition between recent and final Bronze Age,
around 1200-1150 BC, a dramatic crisis invested the
whole low Friulian plain; as the main villages situated
upstream than the spring belt maintained and
expanded their control role, the sites set along
lagoon fringe were completely abandoned; thus a
possible influence of the sea-level rise in limiting the
available land along the coast could be postulated.
Since the final Bronze Age, people concentrated in
some major sites, but Concordia Sagittaria is the
only large village settled in the low plain, probably
supported by its particular physiographic position: a
terrace completely isolated by lagoon inlets. Besides
Concordia, which reached a proto-urban size already
in the lower Iron age, until the Roman epoch in the
rest of the area only few villages existed, and they
controlled the most important paths and fluvial junctions.
Since the 2nd century BC Roman colonization
transformed the Friulian plain in to an agricultural
landscape with field division systems and good road
connections; territorial management affected also
part of the groundwater-fed rivers that underwent
artificial calibration and diversions. The area experienced
the most important human impact till the
Modern epoch.
In the last part of Roman period and especially in the
upper Middle Age, a moister and colder climatic
phase took place, triggering an important avulsion
sequence in the Tagliamento river between 6-8th
century AD. In the same period the lagoons rapidly
expanded inland, over large sectors which were
inhabited until the 4th century and artificially reclaimed
only in the 18-20th century
Late Pleistocene sedimentation in the foreland of South-Eastern Alps
No full textThe glacial expansions occurred in the South-Eastern Alps during LGM and previous glaciations largely deleted the sedimentary record existing in the main valleys, limiting the possibility to reconstruct the Quaternary history of the mountain catchments. But some major constraints about timing and magnitude of phases involved in the evolution of the South-Eastern Alps could be supported by the analyses of the infilling of their foreland, which corresponds to the Venetian-Friulian Plain. The presence of the Adriatic Sea during the interglacial phases allows also to link marine and glacial sedimentary record, which is not possible along the other sides of the Alps. In the last decade, large geological, geomorphological and pedological mapping projects have been investigating the Venetian-Friulian Plain, strongly improving the available information about Late Pleistocene sedimentary processes. This research presents an overview of the evolution of the alluvial and coastal plain since the end of Middle Pleistocene to the Lateglacial. This was mainly possible through detailed field surveys and 20 stratigraphic cores 50–270 m-long. A strong relation between alluvial aggrading phases and glacial periods (final part of MIS 6 and LGM) is evidenced, whereas during the last interglacial the sedimentation mainly occurred in the coastal sectors. During the Tyrrhenian transgression (MIS 5e) the lagoons reached a more landward position than the present. The deposits of Middle Würm are represented by thin alluvial sequences and an important depositional hiatus lasted tens of thousand of years ended around 35-30 ka cal BP. The LGM is characterized by a strong phase of deposition until 20 ka cal BP, then the sedimentary rate lowered and in the Friulian Plain led to apical incision of alluvial systems. Since the Lateglacial an important erosive phase affected the whole plain and brought to the formation of deep and wide incision up to the present coast
Alluvial and coastal stratigraphy in Northern Italy and Northern Adriatic during late Pleistocene and Holocene
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