L'objectif de cette thèse est d'analyser les impacts des changements climatiques sur l'évolution des glaciers alpins. L'impact le plus direct concerne les changements des bilans de masse des 25 dernières années. L'analyse des bilans de masse de plusieurs glaciers au cours des 50 dernières années indique un signal commun sur l'ensemble de la chaine alpine. Il en résulte des variations très importantes de la dynamique des glaciers, en terme de variations d'épaisseur, de longueurs et de vitesses d'écoulement. Le réchauffement climatique a également un impact sur le régime thermique des glaciers "froids" de très haute altitude. Enfin, notre étude s'est intéressée à 3 cas de risque d'origine glaciaire qui sont les séracs de Taconnaz, le lac de Rochemelon en 2005 et la poche d'eau du glacier de Tête Rousse.

Microtextures recorded on quartz sand grain surfaces provide evidence of past environment. Environmental processes, such as transport by glacial ice, create unique microtextures on sand grain surfaces that can be observed under high magnification with a scanning electron microscope. These microtextures and their proportions tend to be unique to environment type, allowing investigators to infer the environmental conditions to which sediments have been exposed, for example to distinguish sediments from fluvial versus mass-wasted environments. Microtextural evidence also allows inferences about the history of sediments of unknown origin. This thesis determines the qualitative and quantitative microtextural fingerprint of glacigenic quartz sand grains deposited by small tropical alpine glaciers in Costa Rica, and compares that fingerprint to the fingerprints of highland Dominican Republic sediments of uncertain genesis, to gauge whether those, individually or grouped, resemble the Costa Rican glacigenic samples. I selected 18 samples (9 each from Costa Rica and the Dominican Republic) and analyzed a minimum of 100 quartz sand grains per sample using a scanning electron microscope. My sample sizes were dictated by the scale of empirical 99% confidence intervals that would allow meaningful comparison of samples. Analysis using literature-recommended numbers of quartz sand grains would entail such large confidence intervals that practically any results would have been indistinguishable. I recorded the presence or absence of 25 microtextures on each grain, and calculated the percentage of each microtexture’s occurrence in the sample. The percentages constituted the sample’s microtextural fingerprint. As a whole, the Costa Rican fingerprints were very similar to each other, and so were the Dominican Republic fingerprints. Further comparison led me to conclude that the Dominican Republic samples are statistically indistinguishable from the Costa Rican glacierized samples. This thesis is part of a larger project establishing protocols for distinguishing glacigenic from non-glacigenic sediments, and testing for glacigenicity of sediments in Costa Rica, the Dominican Republic, and elsewhere. My results can be applied in other studies distinguishing tropical highland glacigenic and non-glacial samples. My contribution will hopefully contribute toward completion of the project’s goals, specifically determining the presence or absence of past glaciers in the Dominican Republic.

Thèse de doctorat : Géographie. Géomorphologie, dynamique des milieux, environnement : Paris 12 : 2006. / Titre provenant de l'écran-titre. Pagination : 330 f. Bibliogr. f. 268-293.

Thesis (Ph. D.)--University of Canterbury, 2009. / Typescript (photocopy). Includes bibliographical references. Also available via the World Wide Web.

In the Kebnekaise Massif, Northern Sweden, the west facing glacier, Rabots glaciär, is loosing volume at a significantly higher rate than east facing, Storglaciären. By analyzing data from automatic weather stations situated on the ablation area on the glaciers we investigated the effect of meteorological differences on ablation. There was a difference in micro-climate between Rabots glaciär and Storglaciären. Generally Storglaciären had slightly warmer and drier air, had less or a thinner cloud layer but more precipitation. On both glaciers a glacier wind is dominant but high wind velocities were common especially on Storglaciären indicating a larger influence from the synoptic system. There was a good correlation for temperature and vapor pressure between the glaciers that indicate that both glaciers are strongly affected by the synoptic system. The meteorological parameters have similar effect on the ablation on the glaciers. Temperature, vapor pressure and the turbulent heat fluxes are the only meteorological parameters that suggest a linear affect on ablation. Net shortwave radiation contribute with the greatest amount of energy for ablation but decreased in relative importance as the temperature increased. Shortwave radiation, sensible and latent heat contributed with a total 184Wm-2 on Rabots glaciär and 222Wm-2 on Storglaciären. Rabots glaciär seem to have a significantly greater relative importance of the turbulent heat fluxes than Storglaciären. Although the differences in micro-climate were not great, using the ablation for Storglaciären to estimate ablation on Rabots glaciär would over estimate the ablation with 0.5m w.e..

The objective of this study is to reconstruct the history of glaciation from the start of Fraser (Late Wisconsinan) Glaciation to the end of deglaciation, for three areas in the Cascade Mountains. The Cascade Mountains are located between the Coast Mountains and the Interior Plateau in southwestern British Columbia. The Coast Mountains were glaciated by mountain glaciation followed by frontal retreat, whereas the Interior Plateau underwent ice sheet glaciation followed by downwasting and stagnation. The Cascades were supposed to have undergone a style of glaciation transitional between these two. Terrain mapping on air photographs followed by field checking was used to locate surficial materials and landforms indicative of glaciation style and pattern. All three study areas were glaciated by mixed mountain and ice sheet glaciation. At the start of Fraser Glaciation, alpine and valley glaciers formed around higher summits as occurred in the Coast Mountains. At the glacial maximum the entire area was covered by the Cordilleran Ice Sheet. Deglaciation was largely by continuous downvalley retreat of active glaciers, contrasting with downwasting and stagnation in the Interior Plateau, and frontal retreat in the Coast Mountains. The scarcity of fresh moraines in the cirques suggests that, unlike in the Coast Mountains, most cirque glaciers were not active at the end of glaciation. Only the highest north facing cirques remained above the local snowline throughout deglaciation and, as a result, glaciers in these valleys remained active and retreated up valley. The pattern of glaciation in the Cascade Mountains was similar to that of other areas which underwent mixed mountain and ice sheet glaciation, such as the Presidential Range in New Hampshire, the Green Mountains in Vermont, mountain ranges in west central Maine and the Insular Mountains on Vancouver Island. However, deglaciation in al l areas was complex and depended strongly on local conditions. For this reason local patterns cannot be predicted easily on the basis of glaciation style. The value of an understanding of glaciation style to improve the accuracy of terrain mapping was also investigated. It was found that the model developed for the Cascade Mountains was of some use in predicting the presence of fine-textured material in valley bottoms and for the prediction of glaciofluvial material overlying till . However fine-textured sediments were not found in al l valleys which were predicted to contain them. The model appears to be most useful as an indicator of where to concentrate field checking in order to locate fine-textured sediments.

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No description available.

Ablation and run-off on the White Glacier (38 km2), Axel Heiberg Island, N.W.T., were studied during the summers 1959-61 and some comparisons were made with nearby glaciers. Techniques of measuring ablation and run-off are described and assessed and the results of longterm, including full season, and short term measurements of both are presented. [...]

During the summers of 1961 through 1964 field parties of the Geographical Branch, Department of Mines and Technical Surveys, conducted studies in the physical geography of north-central Baffin Island. While field research emphasized the glacial geomorphology of the area about the northwest margin of the Barnes Icecap, air photo interpretation over a much wider area revealed the existence of a series of major terminal and lateral moraines stretching for 640 km. (400 miles) in a belt roughly parallel to the heads of the Baffin Bay fiords (Map 1). [...]