ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

flow and subsurface flow would trigger a stage of accelerated
erosion rates.
FIG. 1: Gully evolution conceptual model. I: incision connected to the
drainage net; II: incision disconnected from the drainage net; III: integration
of a connected and a disconnected incision.
The tendency to the integration proposed by the model
had been verified in the field through the estimation of
erosion rates in a potentially integrative gully erosion system.
In order to understand the mechanisms which will
act at the moment of the integration, erosive features named
«regressive alcoves» had been studied on an experimental
field site (fig. 2).
At the experimental. site, most of the gully head extension
was associated to the retreat of the «regressive alcoves».
The main observed mechanisms responsible for the alcove
retreat, act on different space-and-time scales. Under low
intensity precipitation, overland flow transports material
through little «subvertical fillets» adhering to the headeut
wall; under high intensity showers, plunge pools undermine
the. gully head, while «subvertical fillets» promote liquefaction
of non-cohesive materials; under.low intensity,
but.Iong duration, precipitation, seepage erosion becomes
associated with the previous mechanisms.
The interaction in time, at the same place, of the abovementioned
mechanisms, was responsible for the accelerated
retreat of the gully head at the experimental site» .Regressive
alcoves» seem to' be erosive features in which
overland flow and subsurface flow tend to reach the synergetic
interaction predicted by the above mentioned gully
evolution model.
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FIG. 2: Illustration of a regressive alcove. Note the subvertical fillets
concentrating at the base of the alcove.
TOMMASO DE PIPPO, CARLO DONADIO, MICLA PENNETTA,
ALESSIO VALENTE & CARLO VECCHIONE
Morphological evolution of a volcano-tectonic coastal
plain in the Western Neapolitan Area
Dipartimento di Scienze della Terra, Universita di Napoli Federico II,
largo S. Marcellino 10, 80138 Napoli, Italy
The coastal plain of Bagnoli-Fuorigrotta, included in the
active volcanic district of Phlegrean Fields, joins Naples to
Pozzuoli. It is an area with a gentle morphology, modelled
into pyroclastic rocks constituting the framework of both
cities. The plain is few meters up on the present sea-level,
confined eastward by the steep tuff cliff of Posillipo and
westward by Mount S. Angelo and Mount Spina volcanic
slopes. The coastal area extends from NE to SW for about
4 km with an average slant around 1% until the water's edge
of Gulf of Pozzuoli, towards it a sandy beach long 3 km
is developed. Today's concave physiography oriented NW­
SE is the result of many endogenous and exogenous processes
which have taken place during Upper Pleistocene­
Holocene. More specifically the area of Bagnoli at present
has a morphological evolution strictly connected both to
intense pyroclastic eruptions (Neapolitan Yellow Tuff and
other products of the recent volcanic activity in the western
zone of Naples) succeeded in last 14 Kyrs B.P., and
to recently modelling processes of volcanic slopes due to
weathering and to erosion-deposition action of sea-waves.