ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

At present ocean floor relief development alongside the
geological structure of the ocean floor as a whole are
viewed from the two methodological standpoints. The first
assumes the ocean morphostructure having been inherited
from the spreading centres of mid-oceanic ridges (Mor).
The second standpoint proceeds from heterogeneous origin
of the oceanic morphostructure.
Distribution analysis performed on large sea mountains and
oceanic rises attests that inheritance concept bears no
grounds for this class of morphostructures. Mountains and
rises 3-5 km in height are unique to deep-sea basins beyond
the Mor area, and are nowhere to be seen at constructional
boundaries of lithospheric plates. Selective distribution of
large sea mountains and rises is correlated with the thickness
of oceanic litosphere through the geochemical anomalies
of magmatic rock, and peculiar features of the earth's
crust magnetic field. Such relief forms occur on the thick lito
sphere marked by deep sea volcanism, un depleted
Earth's mantle, alkaline magmatism, quiet magnetic field.
Oceanic morphostructure develops from primary formation
of the massive volcanic relief on the thick Mesozoic litosphere
to ensuing riftogenic relief of Mor. Evolution of
the ocean floor morphostructure is determined by evolution
of the earth's crust spreading from scattered to linear
forms.
MOSHE INBAR
New trends in volcanic geomorphological studies
Department of Geography, University of Haifa, Haifa 31905, Israel
Geomorphological processes in volcanic landforms have
been reported traditionally by volcanologists analyzing volcanic
events. Since Mount St Helen's eruption in 1980,
there have been an increasing number of geomorphologists
involved in the study of volcanic depositional material and
dynamic processes in volcanic landforms. The evolution of
landscape is a main theme in geomorphology and volcanic
areas offer the opportunity to monitor landscape evolution
from their beginning. Volcanic landscapes. are characterized
by two common features: there is a clear starting time
of geomorphic development and the lithology is similar in
the different climatic areas of the world. Volcanic morphology
includes two main types of landscapes: basaltic and
pyroclastic. Flood basalt plateaus composed of thick columnar
jointed flows are characterized by deep incised
channels into wide plateaus. In basaltic fields, sediment
yield is low, permeability is high and erosion starts after a
soil layer is developed on the lava flows. In pyroclastic
areas, the rate of erosion is very high after the eruption stage
and it declines rapidly with the developing of the fluvial
system and increasing permeability in the pyroclastic material.
Morphometric studies on cinder cones showed the
possibility of establishing relative dating based on the erosional
stages of the cones in different parts of the world. In
all the sudied areas most of the declining trend of erosion
rates was of several orders of magnitude during the first
years after the eruption. Vegetation cover, soil development
and integration of drainage systems are slower processes
which may last hundreds or thousands of years. The
erosional processes are affected by the different climatic
conditions but are mainly determined by lithological
factors.
Geomorphological studies carried on in different volcanic
areas of the world, like the Canarias Islands, Mexico, the
Southern Andes, Japan elsewhere are a promising basis for
the developing volcanic branch in the geomorphological
sciences.
lOAN AUREL IRIMUS & lOAN MAC
Les effets differencies des structures des domes dans la
morphologie de la Depression de la Transylvanie
Universite «Babes-Bolyai», Faculte de Geographie,
5-7, rue Clinicilor, Cluj-Napoca, 3400, Roumanie
Les structures en domes , representant les plis de la mollasse
neogene sont localisees dans les secteurs du plongement
du soubassement de la Depression de la Transylvanie
ou la couverture sedimentaire est tres epaisse. La genese
des domes represente un processus de longue duree,
mais cet aspect invoque la possibilite que les unes de ces
structures en domes continuent leur evolution en present.
Le diapirisme tectonique c'est le phenomene qui explique
la genese des domes en Transylvanie a cote du «jeu» des
blocs du soubassement. La mobilite differencie du soubassement
et de la couverture neogene (par le sel) est exprimee
dans la morphostructure de la Depression de la
Transylvanie.
La sensibilite de processus de versants dans la configuration
des grandes ensembles srtucturales et des mouvements
neotectoniques mises en evidence par la nature des
formes et par l'acceleration de l'erosion ou de l'accumulation,
representent la modalite de surprendre Ie sens et l'intensite
des mouvements qui ont genere les morphostructures.et
la morphologie de la Transylvanie.
MD. BADRUL ISLAM
Coastline morphology and its evolution
in the Gulf of Cambay
Department of Geology and Mining,
University of Rajshahi Rajshahi 6205, Bangladesh
Forming a narrow entrant of the Arabian Sea, the Gulf of
Cambay forms an important segment of the West Coast of
India which divides the East Mainland Gujarat coast from
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