ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

data are available maps of palaeotemperature estimates for
any time interval can be derived by interpolating between
the point estimates. These palaeotemperature maps can
then be converted into maps of the depth of denudation
that has occurred over the chosen time interval. Finally,
these denudation maps can be used to reconstruct palaeotopographic
maps by replacing the denuded section onto
the present topography, allowing for isostasy. If a series of
maps are prepared at suitable consecutive time intervals
they can then be combined to give an animated image of
the various parameters. These animations, or "movies", are
an excellent medium for investigating processes that vary
both spatially and temporally.
Each of the steps incorporates additional estimates of various
parameters and requires new assumptions to be made,
all of which introduce extra uncertainties in the final
maps. Despite these limitations, with sufficient data and
due care in interpreting the model results, this methodology
provides an extremely powerful tool for quantifying
long-term denudation rates on a continental scale. Large
data sets suitable for applying this methodology now exist
for several regions. An example from southern Africa
will be discussed and demonstrated. A particularly useful
aspect of the technique will be discussed with reference to
South Africa, where volume estimates of the amount of
rock eroded at any time can be compared with volumes of
sediment deposited within the adjacent offshore sedimentary
basins over the same time interval. An important outcome
of this study is the recognition that the cratonic interior
region of southern Africa was deeply eroded in places
during the mid Cretaceous. These data raise some important
questions about the long-term morphotectonic stability
of cratonic regions.
TONY BROWN 1 & EDDY RHODES 2
Late Holocene fluvial response ro climate
and land use change in Central Italy
1 Department of Geography, University of Exeter,
Amory Building, EX4 4RJ, UK
2 Geography Department, Royal Holloway College,
Egham, Surrey, TW20 OEX, UK
This paper presents the first results of a regional study of
valley fill sediments from Central Italy. Four contiguous
basins were selected in an area (Etruria) with relatively homogenous
geology and excellent records of vegetation/climate
and land use information. The vegetation and climate
data is derived from pollen and palaeohydrological studies
of the numerous crater lakes in the region and the land use
information from several archaeological surveys of the area.
The valley infills vary more from basin to basin than within
each basin but in all basins there is a change from the deposition
of channel-gravels and coarse-sands to channel
and overbank sands and silts within the sequence. A variety
of dating methods have been used including, radiocarbon,
palaeomagnetic, pottery and optically stimulated luminescence
(Osl). Osl is particularly useful as it allows the dating
of sediments directly rather than inclusions which can
pre- or post-date deposition. The dated sequences illustrate
major palaeohydrological change between the Roman and
Medieval periods with a the common occurrence of a
major upper unit of post Late Medieval/Renaissance age.
The role of climate and land use change is evaluated and it
is argued that whilst the trigger for accelerated sedimentation
was an increase in storms of high intensity it was also
dependant upon land use variations which conditioned the
form of fluvial response varying from increased lateral migration
with gravel deposition in areas of lower intensity
arable land use to rapid floodplain aggradation by sands
and silt in high areas of high intensity arable land use.
DENYS BRUNDSEN 1 & ROGER MOORE 2
Engineering geomorphology of the coast:
lessons from West Dorset
1 Departement of Geography, King's College London, U.K.
2 Sir William Halcrow and Partners, Hong Kong
A central aim of the paper is to describe the general context
in which an applied geomorphological investigation
for a management project will be set. It attempts to show
how the decision which have to be made at the start of a
project may be affected in different ways by the coastline,
the aims of the project, the historical legacies of altered dynamic
behaviour and structures and the public and administrative
attitudes to change. These are particularly acute
in the area studied, the Dorset Coast of the UK, because it
is one of the most heavily protected Heritage coasts in the
world. Modern attitudes to coastal management in Great
Britain are summarised in the light of recent studies by the
Department of the Environment and the Ministry of Agriculture,
Fisheries and Food.
The Dorset coast in South West England, UK, has a magnificent
array of geomorphological features including
Chesil Beach, the Stonebarrow and Black Ven landslides,
Lulworth Cove and Durdle Door. There is an interesting
history of coastaluse which has greatly influenced the sediment
flux and cliff erosion systems. The structures involved
are now old and there are a number of schemes in progress
to reconstruct the coastal defence systems. This is an
ideal setting in which to discuss problems of contemporary
coastal management in a Heritage Coast area and to compare
the alternatives available as well the general principles
of landscape design which might be employed.
The central question posed by the paper is whether the key
engineering designs can be based on the geomorphological
design of new landforms.
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