ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

On the Po Valley side, the evolution of the river net that
formed on a Plio-Pleistocene pediment was determined by
the particular structural context: owing to the presence in
central Piedmont of the outer fingers of the rising Apennines'
two distinct areas offered routes for the drainage of
southern Piedmont. The Turin corridor took advantage of
the structural trough between the Alps and the Apennines,
and was the drainage path followed by all the Alpine watercourses
starting from the present Bormida di Millesimo
and Bormida di Spigno during the Lower Pleistocene, while
the Alessandria area, a depression in the Apennines
between the Monferrato district and the Ligurian section
of the Apennines, formed the outlet for the smaller streams
running down the easternmost sector of the Langhe pediment,
The Turin route was initially favoured by its better
structural position, but gradually deteriorated throughout
the Pleistocene due to the progressive obstruction of the
Turin rock bar between the tectonically uplifting Turin
Hills and the initially fluvial and then fluvioglacial fan of
the Dora Riparia coated with enormous moraines by each
glaciation, and hence in steep progradation despite its erosion
by the Po. During the Upper Pleistocene - Lower Holocene,
this evolution culminated in the changes in the
Piedmontese drainage pattern known in the literature as
the «capture of the Tanaro». The subsequent erosion phase
gave the present Langhe their cuesta shape, though in
their southern section the almost total wearing away of the
Oligocene marine deposits has resulted in partial exhumation
of the Oligocene morphology. Along the Ligurian­
Adriatic watershed, on the other hand, the head of the
Pleistocene watercourses, once tributaries of the Alessandrine
plain, were altered by the development of a net with
a rectangular pattern determined by fault systems that were
also the cause of the progressive tectonic subsidence of
the Ligurian side, and hence of the northward displacement
of the watershed itself, with the gradual shearing of
the heads of the Padane rivers to the east of the Cadibona
Pass, in keeping with the characteristic morphotectonic
style of the Ligurian section of the Apennines.
In the Alpine area, the most significant event during the
Pleistocene was the transition from the ancient WNW
drainage pattern to the present net, whose main river (the
Tana-to) runs northwards along a structurally and morphologically
low zone that probably formed during the Lower
Pleistocene through reactivation of direct faults already
present in the Middle Oligocene. The Alpine area was also
affected by the elevation in relief energy associated with
the capture of the Tanaro, resulting in a marked increase
in erosion, except where karstification transformed fluvially
modelled areas into poljes or causses.
On the Ligurian side, too, the paths of valleys that had formed
along the ancien pediments were different in the
Lower Pleistocene to those they have today. In the Finale
area, where their evolution can be reconstructed with a
good degree of approximation, there are interesting signs
of competition with the karstification process: initially the
rivers ran round the major karsts, which formed causses,
whereas later they were captured by underground complexes
within the caussess and ended up by forming nar-
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row, boxed-in valleys, some of which were shaped in the
Lower Pleistocene and then abandoned, and have been
preserved until the present as relicts. During the Quaternary,
the fluvial morphogenesis of the whole of the Ligurian
side has experienced periods, which probably correspond
to positive eustatic oscillations, when the valleys became
much wider with flat floors linked to hillside terraces,
alternating with periods, such as the present, in which
the recommencement of relative uplifting is the cause of a
deep incision in the river net, with the shaping of a rather
harsh landscape.
ALESSANDRO BIASINI 1, VALENTINA CAMPO 2,
PIER FRANCESCO GRANGIE 3 & MARIA CRISTINA SALVATORE 1
Remote sensing, photogrammetric monitoring and digital
cartography for regional management of landslides
1Dipartimenta di Scienze della Terra, Universita di Rama La Sapienza,
p.le A. Mora 5, 00185 Rama, Italy
2 via Emilio Lepido 46, 00175 Rama, Italy
3 via Ruzzante 10, 00145 Rama, Italy ,
Landslides and other slope erosion forms are singled out
and located accurately and in a short time using image interpretation
techniques. The use of small scale aerial photographs
allows to get very good results because it is also
possible to have the photogrammetric mapping of both the
interpretation data and the topography of slopes deeply
modified by landslides.
Active phenomena, being most dangerous or of greater
scientific interest, may be monitored by means of multidata
photography and aerial photogrammetry or, if a retrenchment
of futher expenses is required, by terrestrial photogrammetry.
Today this one makes use of new computer
equipments, as digital metric or semimetric cameras, and
software working in personal computers for data plotting.
LAZIO
ABRUZZO
MARE ADRIATICO
FIG. 1 - The investigated area and density of landslides: a) high; b) medium;
c) low.
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