ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

expression and underground, presenting particular problems
with regards to the usual concepts of speleogenesis.
Although there have been some studies of karst development
in the Tertiary, the Pleistocene dune karst areas
(White 1994) and of the some of the surface karst (Grimes,
1994), these are generally of small areas (less than 100 km')
and show some interesting contrasts in features. The
Otway Basin is a large karst area where there is the potential
to understand the regional patterns of karst development
in particular the times taken for karst development in
Pleistocene calcareous dunes.
Karst development in these limestone lithologies shows
substantial variation across the basin and between the different
lithologies. The karst shows important differences in
the number and type of cave present per volume of limestone,
total passage length, passage orientation, passage size,
and cave form. Substantial differences in other karst
features are also evident such as the presence of the distinctive
cenotes and other surficial features in some areas and
yet their complete absence in otherwise similar sites.
Although environmental factors such as relief and climate
do not vary greatly across the basin, there are significant
changes in lithology, structure and underground water
conditions. The variation in karst features can be explained
partly by lithological variation; especially in such highly variable
karst host rock. The overall regional view can add
some important insights into concepts of speleogenesis.
G. RICHARD WHITTECAR 1 & W. LEE DANIELS 2
Use of hydrogeomorphic concepts to design created
wetlands in Southeastern Virginia, U.S.A.
1Department of Oceanography, Old Dominion University, Norfolk,
Virginia, U.S.A.
2 W. Lee Daniels, Crop and Soil Environmental Sciences,
Virginia Tech, Blacksburg, Virginia, U.S.A.
Mitigation wetlands constructed in southeastern Virginia
during the past decade have experienced problems with
inappropriate water levels, excessive erosion and sedimentation,
low levels of soil organic matter, overly compacted
substrates, and sulfidic soils. Most of these problems can
be recognized in the future with adequate planning that
permits sufficient study of the geomorphic and hydrologic
processes active at the mitigation site, and if greater attention
is given to the history of geomorphic processes that
created natural wetlands in that area. New procedures of
assessing wetland functions that use the «hydrogeomorphic»
(Hgm) classification of wetlands require examination
of both surface and subsurface processes. If these
Hgm concepts are expanded to include geomorphic evolution,
they will greatly improve recent practices in the design
and construction of mitigation wetlands.
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STANISLAS WICHEREK
The transfer of pollutants as a result of soil erosion
Centre de Biogeographie-Ecologie, Umr 180 Cnrs,
Ens Fontenay-Saint-Cloud, Le Pare, 92211 Saint-Cloud, France
During recent years research has been carried out to the
north of the Paris Basin on two watersheds in areas of large
scale farming land (loess). In this area there is a considerable
problem of flooding and soil water erosion (up to 30
tonnes/hectare/year). These two processes are major contributors
to the transfer of pollutants which influence greatly
soil and water quality.
In order to quantify these fluctuating movements of liquids
and solids within the watersheds, experiments were conducted
and recordings were made in synchronous and instantaneous
time. The direct link between these movements
was identified in the different plant covers and the
different modes and techniques of land use, making it possible
to establish a classification of zones at risk, from erosion
and deposition, the two processes contributing to the
alteration of relief. To confirm these results another work
method was also employed, the soil erosion marker Caesium-137.
Suspended matter such as nitrogen, phosphorous and
other fertiliser components were the main pollutants to be
found. Although the concentration of nitrogen and phosphorous
did not exceed the published legal limit, the concentration
of suspended organic matter (Som) and pesticides
were very high, for example 260 gil of Som and 690
mg/kg of atrazine sediments. The strongest concentrations
were found in May, during the short runoff period and the
large erosion when the pollutants were not diluted. On the
other hand, concentrations in fertiliser applications were
far less in August.
From these results it is possible to suggest a type of planning
for rural areas, a cartography of risks and to contribute
to the study for sustainable development in agriculture.
VANESSA WINCHESTER 1 & STEPHAN HARRISON 2
Dating with lichens and trees in a west patagonian
landscape subject to flooding
1 School of Geography, University of Oxford, Mansfield Road,
Oxford, OXI3TB, UK
2 Geography Division, University of Coventry, Priory Street,
Coventry, CVl 5FB, UK
The overall aim of our 1996 field work in southern Chile
was to investigate recent landscape changes in the Arco
and the Colonia glacier valleys on the south eastern side of
the North Patagonian Icefield (Npi). Periods of change