ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

to the fluvial dinamics. This process is little represented in
the island where the fluvial processes are rare and highly
conditioned by the prevaling erosion.
The considerable morphological differences of the area also
allowed the localization of three distinct morphogenetic
bands. The first, localized in the western sector, is influenced
more by the structures. The second one, in the centre,
preserves forms and fluvial deposits that define also the ancient
surfaces of the plain. The third band, localized in the
eastern sector, is almost exclusively represented by eolic
processes.
.The most recent and historically documented data are also
reported, as well as the data about the climate and the recent
variations of the River, so to add elements for the
analysis of the relationship between climate and runoff
regime.
SERGIO GINESU & STEFANIA SIAS
Morphocronological correlations between paleosurfaces
and plio-quaternary volcanic events
in the Northen Sardinia (Italy)
Istituto di Scienze Geologico Mineralogiche,
Universita di Sassari, c.so Angioy 10,07100 Sassari, Italy
The presence of flat isolated surfaces long the valley slopes
have been interpreted as erosional terracces, generally placed
in calcareous rocks. Thesesurfaces present a restricted
area, a width till 0.5 to 1 km', Moreovever, it was been possible
to identified some areas included from 20 to 30 km 2
as relicted surfaces. These are characterized by a weak relief
energy and isolated in the landscape. A third surface is
present at altitude between 650-700 m in all the territory.
During the Plio - Pleistocene the island was interested by
a periodical volcanic activity from 5 to 0.14 m.y.B.P.,
many morphologies and deposits have been fossilized by
the basaltic lava flows. The pliocenic volcanic activities have
fossilized flat surfaces and small plains mostly at an altitude
over 600 m. During the Middle Pleistocene the basaltic
lava flows have preserved the fluvial network at 400 ­
300 m altitude. The recentest volcanic events (Upper Pleistocene)
have procteted some lacustrine deposits and some
(2) buried soils formed by the volcanic dam in a subordinate
creek.
The correlation between all the different surfaces and the
dating of each volcanic episodes has permitted to have the
age of these landforms and dating the evolution processes
that have formed the differnt landscape during the last 2
million of years B.P.
It was possible to identifie the climatic changes thanks to
the presence of the deposits under the lava flows, the buried
soils and the periglacial sediments.
GABRIELE GIORGI
Morphological evolution of the Bolognese plain (Italy)
Dipartimento di Scienze della Terra e Geologico-ambientali,
Universita di Bologna, via Zamboni, 67,40127 Bologna, Italy
The aim of this study is to point out the morphological
transformations in a portion of the Po River plain. To this
end several methods were used, such as digital elevation
model-building, archaeological, historical and cartographic
data collecting and soil studies.
In Po Plain rivers tend to flow elevated respect the surrounding
areas, this is due to the continuous sedimentation
in the river bed. When rivers overflow and flood, they
abandon the previous course, creating a new one. The
abandoned relief marks the old river bed.
The invesigated area has been inhabited since the Bronza
Age (about 1000 Be). During the Roman Age, the colonists
developed the architectural grid (Centuriazione) still visible
today. The traces of the ancient settlements are sometimes
visible on the surface, but often are buried under
many meters of sediments.
The ground where the Roman Age finds were made on the
surface, corresponds to those portions of the terrain where
the most developed soils are, where the morphology is quite
regular and the terrain was not subject to flooding over
the last 3.000 years. Where the recent soils lie, the ancient
sites are buried under several meters of sediments, to the
extent that in some cases no finds at all were possible, and
morphology is irregular.
179