ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

culated. Even without considering the other areas underlain
by permafrost, the water volume of the active rock glaciers
corresponds to about 70 % of the estimated water volume
of the glacier. Using the discharge rate of a large rock
glacier as a minimum value and taking into account the
meltwater supplied by all the other existing active rock glaciers
in the catchment, the estimated discharge would constitute
as much as about 13% of themean overall streamflow
during the summer months. Moreover, this does not
include other potential water sources in the permafrost
areas. Changes in the streamflow between the glacier tongue,
situated at the head of the catchment, and 9 km
further downstream confirm that the melting of frozen
ground contributes an important part to the basin discharge.
That means that after snowmelt water released from
the active layer and seasonally-frozen ground produces an
increase of about 300/0 in discharge between the glacier
tongue and the gauging station. For the whole ablation period
1990/91, melting of frozen ground constitutes about
20 % of the total discharge. This simple estimation shows
that the water storage of permafrost and the water supply
due to melting processes play an important role in the water
balance of semiarid mountain regions.
Due to the fact that permafrost areas are highly sensitive to
climatic change (e.g, global warming), there is a possibility
of permafrost degradation and, as a consequence, a shift of
the lower limit of mountain permafrost due to a rise in its
temperature. The loss of water resources and the potential
destabilization of slopes which were previously frozen will
create a variety of dangers (e.g, mass movements).
BRIGITTA SCHUTT
Holocene climatic change at in Central Spain:
reconstruction of holocene palaeoenvironments
by sedimentological investigation of endorheic basins
Physische Geographie, Universitat Trier, 54286 Trier, Germany
Along a northwest-southeast striking transsect through the
Iberian Peninsula core drillings were taken in 23 endorheic
basins. Location and genesis of the endorheic basin vary
from dolines and solution hollows in the central Ebro basin
and the La Mancha area, to a fault-block depression in
the Cordillera Iberica (Laguna de Gallocanta) up to maars
in the area of the Campo de Calatrava (Lamura Manchega),
By geochemical and mineralogical analysis of the basin's
sediments local palaeoenvironmental and palaeoclimatic
conditions during the Holocene have been reconstructed.
The different morphogenetic and lithological environments
of the areas investigated allow to calibrate such
information.
Most of the investigated endorheic basins are characterized
by soluble carbonate or gypseous bedrock side by side
to silicate rock (Paleozoic quarzites, eruptives or rafia topsets).
In these areas landscape budget and morphological
processes show standardized reactions to changes of climate
and water-budget:
1. during humid phases aquaeous solutions, mostly characterized
by carbonates or sulphates, were brought into
the endorheic basins by subsurface flow and have been
precipitated there;
2. during arid phases subsurface flow and input of
aqaeous solutions into the endorheic basins were reduced,
while erosional processes were intensified because of decreasing
vegetation cover;
3. the increasing human impact since Neolithic Age caused
an increasing ecosystem degradation which in many cases
results in a geomorphological response that effects a sedimental
structure which is simliar to that deposited during
phases of arid environmental conditions.
The results of geochemical and mineralogical analysis of
sediments indicates that in the whole area of the Iberian
Peninsula the climatic conditions governing sedimentation
during the Holocene changed from humid and sub-humid
to the present sub-arid conditions, but was interrupted by,
with local varying intensity and frequency, phases of increased
humidity. Especially the relation of sediments originated
from precipitation (halite, gypsum, calcite) to detritical
sediments (silicates) gives information about the
conditions of water-budget during sedimentation. These
understanding on geochemical composition of lake-sediments
were supplemented by mineralogical analysis, because
in several cases solutes were precipitated secondary
by aqaeous solutions which immigrated into the sediment's
interspace after sedimentation.
ANDREI SELIVANOV
Coastal morphological changes under the various rates of
. sea-level changes: Late Pleistocene and Holocene
examples from the Russian seas
Water Problems Institute, Russian Academy of Sciences,
Novaya Basmannaya St. 10, p.o. box 231, 107078 Moscou, Russia
Examples from the depositional sand coasts of the White
Sea and the Sea ofJapan provide valuable information regarding
the importance of sediment budget and the direction
and rates of sea-level change for patterns of coastal
evolution. These examples demonstrate a limited applicability
of the Bruun Rule and its modifications to the prediction
of shoreline movement under the sea-level change.
A moderate underwater coastal slope and an excessive or
insufficient sediment supply may result in the prevalence
of deposition during sea-level rise and erosion during its
fall. In general, the faster sea-level rise, the higher the possibility
of burial, drowning, or destruction of the coastal
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