The work outlined in this thesis was a part of the program of glacial studies undertaken by the Arctic Research Expedition to Axel Heiberg Island, N. W. T., during the summer of 1960. The expedition was organized for the purpose of investigating the fields of glaciology, geology, meteorology, botany and other closely related subjects as they applied to Axel Heiberg Island. [...]

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This thesis addresses the consequences of the last glaciation on the distribution and genetic diversity of arctic flora. The principal aim is to infer the full-glacial and postglacial migrational history of Dryas integrifolia M. Vahl. (Rosaceae) from the intraspecific phylogeny of cpDNA haplotypes along with pollen and macrofossil distribution data. The results suggest that four refugia existed during the last glaciation and that each served as significant sources of recolonization when the ice retreated. The two most important refugia are located in the northwestern Arctic (Beringia and the High Arctic), with two other refugia located southeast of the ice sheet and along the coastal regions of the eastern Arctic. High genetic substructure among populations is likely attributable to past vicariance and recent recolonization events, whereas high local diversity is probably indicative of recolonization from several sources and high gene flow in recent time.

Les travaux menés dans le cadre de cette thèse portent sur la mesure de la variabilité de déplacement de surface de glaciers alpins, par GNSS et imagerie radar. Le glacier tempéré d'Argentière, situé dans le massif du Mont-Blanc et équipé de stations GPS et de coins réflecteurs, est plus particulièrement choisi comme site d'étude. A l'aide de la méthode de corrélation d'amplitude, 44 images TerraSAR-X acquises en 2009 et 2011 sont traitées, permettant d'obtenir 38 champs de déplacement 2D, ainsi que 6 champs de déplacement 3D. En parallèle, l'analyse de 5 années de données GPS continues issues de 2 stations implantées sur le glacier, permet de connaître la vérité terrain. Une stratégie d'analyse GPS, qui optimise la précision de la mesure de position sur un objet en mouvement, a été choisie. Les résultats GPS révèlent plusieurs régimes dynamiques du glacier d'Argentière. La variabilité journalière indique un déplacement de surface en stick-slip et la variabilité intra-annuelle permet de mettre en évidence un amincissement constant du glacier d'Argentière. Au printemps 2011, les résultats GPS permettent de suivre la mise en place d'un système de drainage sous-glaciaire. Les résultats radar permettent une visualisation des variations du déplacement de surface d'une grande résolution spatiale. Au niveau temporel, des accélérations du déplacement sont mises en évidence pendant les périodes de fonte importante. Si une bonne corrélation entre les variations générales du déplacement du glacier d'Argentière issues des deux sources de données est obtenue, les travaux de cette thèse révèlent une importante complémentarité entre le GPS et l'imagerie radar.

Bridge Glacier is a prominent eastward-flowing valley glacier located on the east side of the Pacific Ranges within the southern British Columbia Coast Mountains. The terminus of Bridge Glacier has retreated at rates ranging from 0 to 125 m/year over the last 50 years and currently calves into proglacial Bridge Lake. Field investigations of the recently deglaciated terrain at Bridge Glacier in 2002 and 2003 led to the discovery of detrital boles and glacially-sheared stumps. Dendroglaciological analyses of this subfossil wood allowed for the construction of five radiocarbon-controlled floating tree-ring chronologies. The relative age and stratigraphic location of these samples revealed that Bridge Glacier experienced at least four periods of significant advance during the late Holocene: a Tiedemann-aged advance at ca. 3000'4C years BP. an unattributed advance at ca. 1900 '4C years BP. a First Millennial Advance at ca. 1500 '4C years BP. and an early Little Ice Age advance at ca. 700 '4C years BP. Lichenometric investigations at eight terminal and lateral moraine complexes led to the recognition of early Little Ice Age moraine-building events during the late 13th to early 14th centuries. with subsequent Little Ice Age episodes in the mid 15th. early 16th. mid-late 17th, early 18th, mid-late 19th, and early 20th centuries. These interpretations provide an exceptional long-term perspective on the extent and character of a glacier within this region during the late Holocene.

This investigation uses dendrochronologic and radiometric techniques to infer the timing of glacier advance for four ice lobes that are drained by Manatee Creek in a remote valley located in the southern Coast Mountains, British Columbia. Dendroglaciologic evidence exposed by retreating glaciers provides evidence for increasing complexity in the Holocene glacial record, particularly for mid-late Holocene events. Since Holocene ice fronts periodically extended below treeline in the region, previous glacier advances overrode and buried forests beneath till deposits. The dendroglaciologic evidence presented here corroborates the record of glacier advances described for other southern British Columbia Coast Mountain glaciers and details ice front position at ca. 4270 14C yr BP, 3430 14C BP and 2350 14C yr BP. Well-preserved sequences of lateral, nested moraines were mapped and profiled to delineate the boundaries of Manatee and Oluk glaciers. Relative dates provided by lichenometry and dendrochronology were used as limiting dates for the deposition of 5-6 moraines during the late 14th, early 16th, early 18th, 19th, and early-20th Century. Reconstructions of Holocene glacial history offer insight into the regional, climatic regime and add to the discussion about pervasive, millennial-scale cycles.

The sensitivity of glaciers in the Southern Alps of New Zealand is evaluated to identify the nature of recent climate change. Past glaciological observations are compiled and to these are added 4 summer field seasons on the Tasman (including Hochstetter), Dart, Fox and Franz Josef Glaciers. The field data are an important aspect in the calibration and verification of glacier modelling. The detailed studies of these glaciers provides the basis for assessing the glacier and climatic changes over the whole glacierized region. (For complete abstract open document)

This research demonstrates the feasibility of a full-field photographic method for remotely measuring the movement of large deforming objects. 'Large objects' could include civil engineering structures such as dam walls, buildings and bridges, and geological phenomena such as glaciers. Such structures must be examined in situ and preferably by a non contacting method. The objective is to measure motion from time lapsed photographs of the moving object. The method is based on speckle photography which is a well developed optical metrology technique for deformation measurement of engineering structures in laboratory conditions. Its application to large scale structures illuminated in sunlight at high imaging demagnifications has demanded some significant extensions and modifications to the technique. Imaging these large objects offers a unique set of challenges which include the establishment of rigid tripods from which to take the time lapsed photographs in rugged glacial terrain, the variation of illumination in terms of both quality and angle of incidence, imaging through several kilometres of turbulent atmosphere and recording the signature texture of the object surface onto film at high imaging demagnifications. The effects of these factors are considered both conceptually and experimentally, providing fundamental understanding of the problem. Displacement analysis is performed primarily by interrogation of time lapsed negative pairs using an unexpanded laser beam, as is generally the case in speckle photography. An automated system is developed to make practical the analysis of multiple points in the field of view. In parallel, a new digital technique is introduced where displacement results are obtained by pattern matching in digital versions of the speckle images. This analysis method is shown to be highly suitable for the application to glacier flow. Registration of the pair of time lapsed images is performed by calculating the affine transform describing the image misalignment (introduced at either the recording or analysis stage) within the non-deforming areas of the field of view. Use of this novel technique allows pairs of single exposures, rather than double exposures, to be examined, and it also increases the sensitivity of measurement. Two dimensional motion fields representing glacier flow are presented, leading to the conclusion that the technique is feasible in sunlight illumination, for a variety of glacial surface types and at high imaging demagnifications.

Thesis (doctoral)--Universität Trier, 2005. / Includes bibliographical references (p. 118-129).

Thesis (M.Sc.)--Victoria University of Wellington, 2008. / Includes bibliographical references.