ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

DANIELE AROBBA 1, MARIA CRISTINA BONCI 2 ,
MARCO FIRPO 2, MAURO PICCAZZO 2,
FLAVIO POGGI 2 & AGOSTINO RAMELLA 3
Environmental changes in the Centa River delta area
(Albenga, Western Liguria, Italy)
1 Istituto Internazionale di Studi Liguri, Laboratorio di Palinologia,
Museo Civico, Finale Ligure, Italy
2 Dipartimento di Scienze della Terra, Universita degli Studi di Genova,
c.so Europa, 26, 16132 Genova, Italy
3 Servizio di Protezione Civile, Comune di Genova, Italy
The morphology of the coastline between Caprazoppa Cape
and S. Croce Cape is characterised,by the presence of
the Centa River and, above all, of its delta system, which,
according to Galloway (1975), is «wave dominated». Its
changes have been outlined through photo-interpretation,
the analysis of historical sources and stratigraphic seismic
sections of the continental shelf.
Sedimentological, micropalaeontological and palynological
studies have been carried out on six vibrocores, sampled in
the prodelta area, and on many rotary cores, drilled in the
delta plain. A preliminary reconstruction of holocene evolution
of the delta system could have been sketched out by
means of these analyses, complemented by two radiocarbon
dates performed on significant samples.
Four cores have been particularly informative for our research.
K2 and K4 cores were extracted from the submarine
delta on the 50 m isobath. Curia 1 and Curia 2 were
drilled in the subaerial delta plain on the left side of today's
Centa riverbed, in the area between the coastline and
the buried vestiges of Roman Albingaunum.
A chronological parallel between K2 and K4 cores has
been made possible through a systematic comparison
'between the frequency curves of the homologous pollen
taxa and their bottom levels can be considered approximately
contemporary. Similar analyses have been carried out
.on a rich organic clay and peat level sample from a 40 m
'long core (Sl), drilled in the delta plain, inland of Curia 1
and Curia 2. The bottom of this 30 em thick level, located
at a depth of 12 m below the surface of the plain, has been
14C dated to 5,940±50 B.P .. The K2 base level returned an
age of 2,495±60 B.P. On these bases the bottom of the Sl
peat level can be referred to the Atlantic period (5,500­
2,500 B.C.). This phase was characterised by a climatic optimum,
the first holocene period marked by post-glacial
conditions, to be defined as temperate-warm with slight
thermic excursions, precipitation distributed with regularity
throughout the year and progressively increasing humidity.
In accordance with bibliographic data, this period's
arboreal vegetation is characterised by the net prevalence
of white firs and very low frequencies of beeches. Infact,
the Abieti-Fagetum phytocoenosis has only been widespread
in the Ligurian Apennine and French Provence
since the second half of the Atlantic period, around 3,500­
3,000 years B.C.. Examining the results of carpological and
palynological analyses, the area surrounding the S1 core
drilling site seems to indicate the presence of permanent
swamps as well as zones flooded only periodically by fresh
water. The shoreline was probably not far from this area.
This is suggested by the not inconsiderable presence of
coastal halophyte plants pollens. Hygrophylous woods
characterise predominately water free zones Or those experiencing
only occasional floodings. These plants progressively
colonise new and wider areas. The top of the peat level
illustrates the effects of marine transgressions into the
swamps, which gradually turn into coastal marshes.
A sudden depositional facies change, at a depth of 6 m below
the surface of the plain (-4 a.s.l.), appears to be the
main feature outlined by both sedimentological and micropalaeontological
analyses carried out on Curial and Curia2
cores; intact, the deeper half of both cores demonstrates
characteristics typical of shallow submarine environments
while the upper portion is marked out by elements attributable
to a subaerial continental facies. Some textural sequences
of the «coarsening upward» type can be identified
in the marine sediments. These intervals reflect a good fit
in the forams distribution curve. Similar sequences have already
been described in cores sampled in other delta
plains.
LUIGI ARRIGONI, FILIPPO CATANI & DGO TARCHIANI
Some considerations on the slope evolution in the
Island of Stromboli (Messina, Italy)
Dipartimento di Scienze della Terra, Universita di Firenze,
via La Pita 4, 50121 Firenze, Italy
The Island of Stromboli is located in the northern part of
the aeolian volcanic arc and.consist of an active volcano
which extends more than 2,000 m below the sea level. The
island, with conic shape, is 924 m high, with an area of
about 12 km',
The outcropping terrains date back from 10 5 years to recent.
In the past Stromboli was subject to volcano-tectonic
phenomena, mainly located on the Sciara del Fuoco valley.
The landslides, prevalently fall and toppling, involve volcanic
materials (lapilli, tuff and lavas) with blocks with a
volume up to some cubic metres reach distances of about
200 m. The areas of the island where the gravitative phenomena
have the greater occurrence may be recognised near
Cugno Anghiastro in, the northern part in corrispondence
ofSciara del Fuoco and in the western part along the cliff
in front of Ginostra village.
As regard the coast, the south-western cliffs show the higher
recession rate, while the low sandy coast seems' to be
in growth in the north-eastern side.
Since the action of the geomorphological processes appears
to be very intensive, due to the morphologicaland litological
conditions, the volcanic and seismic activity and
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