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Christine ElliottPh.D. Research Profile: Christine Elliott

Rock weathering processes in Antarctica

The primary objective of my research is to quantify the role of moisture in the weathering of rock in a cold environment such as Antarctica. Goudie (1994, p556) describes weathering as “….one of the most important geomorphological and pedological processes” and Selby (1993, p189) defines it as “…. the process of alteration and breakdown of rock and soil materials at and near the Earth’s surface by physical, chemical, and biotic processes”. It is weathering that initially breaks up rock, or reduces it sufficiently in strength, to enable the processes of erosion to occur and it is rock weathering that provides the materials for soil formation to begin. Consequently, the rate at which rock weathering occurs is important because it determines how quickly, or how slowly, the soil and landscape develop.

Base CampThere are a range of physical weathering processes including the effects of alternate and repeated freezing and thawing (frost action); heating and cooling (insolation weathering); wetting and drying (hydration) and the crystallisation of salts due to the growth of crystals from solution, thermal expansion or hydration (salt weathering). Minerals remain largely unaltered by these physical processes, whereas chemical weathering involves the decomposition or decay of the minerals. Biological weathering includes the breakup of rock through the action of lichens or fungi for example. There is still an ongoing debate about which of the these weathering processes operate in particular environments as well as their relative effectiveness in producing actual rock breakdown. In addition, although the important role of moisture has been identified there has been no systematic study of how increasing quantities of moisture may influence the type of process operating. Few attempts have been made to quantify the influence of changing moisture availability on weathering rates and, with one or two notable exceptions, very few rock weathering studies have attempted to develop models that will predict weathering rates.

One of the more challenging aspects of investigations into rock weathering is the complexity of factors involved and Antarctica is an ideal environment to undertake such research as its low moisture (at least in the area under consideration here) and extremely low temperatures enable some of these factors to be excluded or minimised. For example, biological weathering would be expected to be minimal over the timescales under investigation in this study. In addition, the research will contribute to the Latitudinal Gradient Project, a joint initiative between the U.S., Italian and New Zealand Antarctic Programmes, that uses the effects of changes in latitude on the environment as a proxy for getting a better understanding of what might happen under changes in climate.

In order to get a better understanding of the influence of different moisture levels on rock weathering processes and rates, a series of laboratory simulations will be conducted on rock samples from four locations in the field and the effects of moisture isolated from other factors. An empirically based mathematical model will then be developed that will predict changes in weathering rate along the Victoria Land Coast depending on changes in moisture in the rock. Field observations, required to determine the temperature and moisture cycles for the laboratory simulations, were undertaken at Victoria Valley (77° 23’S; 161° 55E) and Gneiss Point (77° 24’S; 163° 44E) during the 2002/03 season and Terra Nova Bay (74° 41’ S; 164° 07’ E) and Teall Island (79° 03’ S; 161° 56’ E) in the 2003/04 season. A final season of fieldwork will be undertaken in the 2004/05 summer.

References

Goudie, A.S. (Ed.). (1994). The Encyclopaedic dictionary of physical geography. (2nd Ed.). Oxford: Blackwell
Selby, M.J. 1993: Hillslope Materials and Processes (2nd Ed.), Oxford University Press, Oxford.

Christine Elliott in Field

Figure 2: Drilling holes to
enable subsurface temperature
measurements to be made

Personal Profile

I returned to University studies after a long career in the health system (that’s a hint to my age!); initially enrolled as an extramural student at Massey University, I took my 4th year papers part time at Canterbury University. I then took the plunge and gave up work to become a full time PhD student in February 2002. Part of the impetus for doing this was my ongoing interest in the landforms and processes of cold climates (no idea why I am interested in these things, but I always have been) and a chance to study these formally, and partly as a result of the opportunity I had to participate in the Gateway Antarctica Graduate Certificate Studies course, which gave me a taste of full time study as well as an opportunity to visit Antarctica. My research nicely combines these interests and enables me to continue my affiliation with one of the most unique parts of our globe.

Publications:

Elliott C, 2003, Rock Weathering Processes in Antarctica: A comparison of some recent studies with those from the Northern Hemisphere, New Zealand Geographer, Vol 59, No 1, pp 50-60.
Elliott C, 2003, Modelling the influence of moisture variations on physical rock weathering processes in Antarctica: proposed investigations and preliminary results, in Wilfried Haeberli & Dagmar Brandova (eds), Extended Abstracts 8th International Conference on Permafrost, Zurich, Switzerland, pp 20-25.
Elliott C, forthcoming, Surface moisture availability and rock weathering in cold climates, New Zealand Geographer.

Lawson W and Elliott C, 2003 Strain-rate effects on the strength of debris-laden glacier ice, NZ Journal of Geology and Geophysics.

Supervisor

Assoc. Prof Ian Owens
Department of Geography

Co-Supervisors

Dr Barry Fahey
Department of Geography

Professor Bryan Storey
Gateway Antarctica