ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

and dams) are analysed in relation to the hydrodinamic
characteristics of the flow, the hydraulic geometry of the
channel and its bed-forms. Special attention is given to the
calculation of local erosion of the bed by turbulence
around the bridge piers and downstream from the dikes or
dams, along with the evaluation of the sediment retention
rates of the latter and their rapid loss of efficiency.
Scour at bridges is studied taking into account the approach
stream velocity and depth, the pier size, shape and
orientation relative to the flow, natural variation of bed
elevation as sand dunes pass and the local adjustments of
bedforms upstream and downstream from the piers.
Downstream from the dams different morphological changes
are analysed: a reduction of channel capacity, depositional
berms within the old cross-sections and a local scour
advance.
EMANUELE CONGIU 1
, MARCO NERI 2
,
GIUSEPPE OROMBELLI 1
& MANUELA PELFINI 1
Geomorphology of the NE slope of Mt. Etna (Sicily, Italy):
evidence of Late Pleistocene glaciers
1 Dipartimento di Scienze dell'Ambiente e del Territorio,
Universita di Milano, via Emanueli 15,20129 Milano, Italy
2 Istituto Internazionale di Vulcanologia,
piazza Roma 2,95123 Catania, Italy
The evolution of Mount Etna over the last 15.000 years
and particularly the formation of the deep and extensive
erosion depression of Valle del Bove (valley), has left several
parts of the volcano isolated and no longer covered by
the lava from the summit craters. Therefore, in these areas,
it is possible to find early volcanic products, belonging to
eruption centers preceding the Recent Etna" (15 Ka - Present-day),
and which have been eroded and altered to
varying degrees by morphogenetic agents.
A large sector with these exposure characteristics is found
on the high northeast flank of Mt. Etna, in the area
between Piano delle Concazze and Serracozzo. The present
topographic surface in that area, has essentially preserved
relict landforms' of ages of over 15.000 years and
which developed on volcanic products belonging to the
eruption center of the Ellittico (34 Ka-15 Ka),
The geomorphological survey conducted in this sector of
the volcano made it possible to gather detailed information
on both landforms associated with effusive magmatic processes
and other landforms more typically associated with
exogenous morphogenetic processes. The data thus collected
are useful for a reconstruction of the history of the evolution
of Mt. Etna starting from the Pleistocene and serve
also as a starting-point for an understanding of the evolution
of the climate in the Mediterranean during the Quaternary.
Among the landforms that are most characteristic of this
old flank of the Ellittico, the rounded edges of the caldera,
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lava flows that are frequently stripped of the scoriaceous
portion and a relict drainage network composed of deep
barrancos and rock beds with erosion potholes and
smoothing. These landforms unmistakably suggest that the
morphological and climatic conditions of the past differed
significantly from present-day conditions and were probably
characterized by heavier precipitation, including snow.
To account for the presence of these landforms, the
authors also took the following hypothesis into consideration.
During the last glacial maximum (25 Ka - 15 Ka), there
may have been extensive glacierets or actual glaciers in
the higher sectors of Mt. Etna, which reached altitudes of
3600-3700 a s.l. with the Ellittico.
This continues to be one of the most probable hypotheses,
although no evidence was found that could considered as
being of unquestionable glacial origin such as end moraines'
roches moutonnees or striated pavements.
MIHAELA CONSTANTIN
Some considerations concerning to geomorphological
hazards in Panatau Region (Buzau Subcarpathians)
Institute of Geography of the Romanian Academy, 12,
Dimitrie Ravovita, 70307 Bucuresti 20, Romania
The Romanian Sub carpathians are recognized as being one
of the regions in Europe most affected by intense geomorphological
hazards. It is the youngest orogenic unit in
Romania (built of folded and faulted Neogene molasse deposits)
associated with Mio-Pliocene tectonic activity which
continued into Quaternary. The seismicity of the region
coincides with a continental climate that gives torrential
precipitation and a land use which has large produced much
recent deforestation areas. The results is large areas affected
by intense erosion processes and landslides.
The Panatau region is situated in the southern part of Blidisel
hill (Buzau Subcarpathians) and is developed on molasse
deposits (sandstone, sands, marls and clays), who belongs
to Calvini -Soimari syncline. The studied region is affected
by intense mass movement and gully erosion.
Correlating the geomorphological map with the main hazards
triggering factors (i.e, geological factor, heavy rainfalls
and social-economical factors), the geomorphological risk
map could be worked out.
ANDREA CORONATO
Late-Pleistocene alpine-type glacierization
in the Fuegian Andes, Argentina Oat 54°)
Cadic-Conicet C.C. 92, 9410 Ushuaia, Argentina
Universidad Nacional de la Patagonia, Darwin y Canga,
9410 Ushuaia, Argentina