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GLACIER FLUCTUATIONS AND LICHEN SIZE-FREQUENCY DISTRIBUTIONS (NUNAVUT - CANADA)
MERCIER, GENEVIEVE University of Ottawa.
Lauriol, Bernard University of Ottawa.
The Akshayuk Pass, Auyuittuq National Park in Cumberland Peninsula (Baffin Island – Canada), is a U-shape valley where numerous glaciers of all sizes are present. Modern glacier fluctuations in this valley have been previously analyzed using lichenometric studies, based on maximum thallus measurements (Innes, 1985; Locke and al., 1979). Various lichenometric studies in Cumberland Peninsula have (1) determined that the maximum extent of glaciers occurred during the Neoglacial period (Davis, 1985; Graham, 1997) and (2) established a growth curve for Rhizocarpon geographicum for the northeastern part of the Cumberland Peninsula (Andrews and Webber, 1964; 1969; Miller, 1973; Miller and Andrews, 1972).
This presentation is to discuss results obtained at various sites during the fieldwork season of 2002 and 2003, including some moraines previously studied by Thompson (1954), Davis (1985) and Graham (1997). Specifically, these results focused on two time periods: (1) quantifying the actual glaciers snout retreat using aerial photographs and satellite images, and (2) analyzing the modern glaciers snout fluctuation using size-frequency distributions and percentage cover analyses of lichen populations.
Modern glaciers snout retreats are studied using the following three features. First, a comparison of maximum thallus measurements and size-frequency analysis is made to evaluate the former. Statistical analyses were executed to determine a good age surface index based on the size-frequency distribution analyses of lichen populations. Secondly, environmental variations between sampling sites were estimated with geomorphological and ecological indicators using population characteristics. Thirdly, relative dates supported by the lichen percentage cover were established within sampling sites. Also, absolute dates were recognized for the six glaciers studied, based on the age index resulting from the lichen size-frequency distributions and growth curves.
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