ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

PAOLO SANSO
The ancient landforms of the Apulia region
(Southern Italy)
Dipartimento di Geologia e Geofisica, Universita di Bari,
via Orabona 4,70125 Bari, Italy
The Apulia region constitutes the southwestern margin of
the Adriatic plate in the central Mediterranean and it is
considered to be a poorly tectonized area in the apenninic
foreland. The Apulian foreland shows a rather uniform
structure with a variscan crystalline basement and an approximately
6 km thick mesozoic carbonate platform sequence.
This sequence is overlain by thin discontinuous
Tertiary and Quaternary deposits, generally represented by
thin carbonate-terrigenous sediments.
The landscape of this region is generally thought to be the
result of morphogenetic phases which occurred during the
Quaternary period, due mainly to the effects of relative sea
level changes, tectonic and karstic processes. Nevertheless,
a more careful analysis of the Apulian landscape reveals in
several areas the occurrence of landforms developed during
theTertiary.
Etchplains are the most common among these landforms
as they are recognizable on the Gargano promontory, on
the Murge plain and in the Salento peninsula. They formed
.. during a long period of continentality during almost
all the Tertiary when deep weathering of Mesozoic limestones
was promoted by tropical humid or subtropical climatic
conditions. Their evolution was probably interrupted
by important Pliocene tectonic phases which broke up
the etchplains into several surfaces, each one characterized
by a subsequent differing evolution.
A wide etchplain characterizes the top surfaces of Gargano
promontory. It is broken by NW-SE, NE-SW and E-W
fault scarps, forming several surfaces at different altitude.
The main, most elevated surface is located in the central
area of Gargano promontory and presently slopes towards
the NW between 900 and 450 m of altitude. Its surface
lacks any lateritic cover, this having been stripped away by
a well-developed drainage network (stripped etchplain);
both the etch surface and the valleys are strongly affected
by karstic processes which induced the formation of numerous
dolines. The density of dolines varies in direct ratio
with altitude up to 105 dolines/km', probably due to the
diachronic removal of the weathering cover. The main surface
is bordered to the NE by a lower plain, at about 500
m altitude, which still retains remains of the originallateritic
cover. It is characterized by some broad colluvial dolines,
generally alligned along main fault lines. On the
southern side of Gargano promontory lowered strips of etchplain
were smoothed by Pliocene and Pleistocene marine
transgressions.
The Murge Alte landscape is represented by a wide stripped
etchplain gently sloping NW between 450 and 679 m
altitude. It is bordered by fault scarps to the Wand SE
and by a flight of steps of gently sloping seaward marine
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surfaces to the Nand NE. In detail this plain is marked by
isolated areas of high relief and broad depressions. The
former usually represent the highest points of low ridges
running NW-SE which rise 50-100 m above the surrounding
areas, while the latter represent wide, flat endoreic
basins elongated NW-SE which retain a Late Pleistocene
volcanoclastic cover. The particular morphology of this etchplain
is probably due to the presence in the rock body of
parallel zones of widely-spaced and closely-spaced joints,
associated withbordering faults oriented NW-SE formed
in the Lower Pliocene.
On the Salento peninsula, a Tertiary etchplain along with
its lateritic mantle was fossilized by Late Miocene calcarenitic
deposits. However, on the horst of Serra di Poggiardo
the Miocene cover has been eroded so that a small part of
this etchplain has been re-exhurned. This surface, placed at
about 120 m of altitude, is represented by a rolling plain
characterized by broad, wide shallow depressions and
showing a lateritic cover of variable thickness.
Along the southeastern coast of the Salento peninsula
another impressive pre-Quaternary landform has been recognized.
In fact, the general flatness which characterizes
the landscape of the Salento peninsula is abruptly broken
along its southeastern coast, stretching from Capo d'Otranto
to S. Maria di Leuca, by a steep, high slope. Recent
geological research suggests that this landform could be
the morphological effect of a carbonate platform margin
evolution. In fact, from the Late Cretaceous onwards the
eastern margin of the Apulia Platform became established
roughly along the present coastline of southeastern Salento.
On this slope reef depositional systems of Paleogene
and Miocene age developed. The shape of the present coastal
landscape still reflects the originary Tertiary reef
morphology superimposed on the late Caretaceous
platform margin notwithstanding the subsequent morphological
modifications represented by younger fault scarps
and some Middle-Late Pleistocene abrasion platforms.
SUBIR SARKAR
Landslides in Darjiling Himalaya, India
North Bengal University, West Bengal, India
Landslide is the most pervasive of natural problems that
undermine the economic and cultural development of
Darjiling Himalaya. The diversity in slope components,
geometry, site and situation, micro-regional susceptibility
to degradational processes, micro-geology, micro-climate,
depth of soil, its physical and chemical properties, vegetation
with differential canopy and root system, unplanned
growth of settlements and roadssewer systems, imprudent
land-use etc. have led to recurring landslides. Record since
1849, show a sharp acceleration in the rate of devastating
slide occurrences, leading to great loss of life and heavy damage
to land and property. Extensive heedless deforesta-