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. [...]

No description available.

Glacial geomorphology contains information about former climate which is required for modelling global climate change. Most peaks over 5500 m in the Cordillera Occidental show signs of former glaciation although few at present support perennial ice. Cirque headwalls, large sub-parallel lateral moraines, terminal moraines and minor re-advance moraines were measured at six representative study sites, as were active and inactive rock glaciers. The largest sets of lateral moraines are assumed to have formed when glaciers were in equilibrium at the peak of the last glaciation, and a succession of minor re-advance moraines was probably deposited during retreat of the ice. The radiometric age determinations corroborate existing opinion that this retreat began in the central Andes around 14 000-11 500 years BP. Reconstructed former equilibrium lines on fourteen selected palaeo-glaciers range in altitude from 4625 m at 16°S to 4775 m at 22°S. Five methods of former ELA reconstruction were tested based on geomorphological evidence collected in the field. The results imply lowering of the ELA caused by lower temperatures and increased precipitation compared to the present. The maximum extent of glaciation in the Cordillera Occidental appears to have been reached late in the last glacier cycle because of a shortage of available moisture which inhibited glacier growth when temperatures were colder. Active rock glaciers appear to respond to the thermal rather than the hydric regime and terminate close to the 0°C isotherm which was 300 m lower during deglaciation than at present.

Glacier facies represent distinct regions of a glacier surface characterized by near surface structure and density that develop as a function of spatial variations in surface melt and accumulation. In post freeze-up (autumn) synthetic aperture radar (SAR) satellite imagery, the glacier ice zone and dry snow zone have a relatively low backscatter due to the greater penetration of the radar signal into the surface. Conversely, the saturation and percolation zones are identifiable based on their high backscatter due to the presence of ice lenses and pipes acting as efficient scatterers. In this study, EnviSat ASAR imagery is used to monitor the progression of facies zones across Devon Ice Cap (DIC) from 2004 to 2011. This data is validated against in situ surface temperatures, mass balance data, and ground penetrating radar surveys from the northwest sector of DIC. Based on calibrated (sigma nought) EnviSat ASAR backscatter values, imagery from autumn 2004 to 2011 shows the disappearance of the ‘pseudo’ dry snow zone at high elevations, the migration of the glacier and superimposed ice zones to higher elevations, and reduction in area of the saturation/percolation zone. In 2011, the glacier and superimposed ice zone were at their largest extent, occupying 92% of the ice cap, leaving the saturation/percolation zone at 8% of the total area. This is indicative of anomalously high summer melt and strongly negative mass balance conditions on DIC, which results in the infilling of pore space in the exposed firn and consequent densification of the ice cap at higher elevations.

No description available.

No description available.

No description available.

The evolution of the landscape of Vestfirđir, made almost entirely of volcanic rocks, is traced from the lilocene, when the oldest rocks formed, through the Pliocene and Pleistocene. Volcanic activity ceased first in the north western part leaving a basalt plateau with occasional large volcanoes protruding. Fluvial erosion, guided by a westerly dip of the plateau and tectonic lineaments, left a well developed drainage pattern there by the rime volcanic activity ceased in the southeast. The snowline fluctuated widely during the Plio-Pleistocene. Cirque and valley glaciations were very effective in sculpturing the landscape where the preglacial relief was greatest, in the northwest. Ice sheet glaciations affected the whole peninsula and offshore areas with linear erosion dominant in the northwest and areal scouring elsewhere. The glacial geomorphology of Dyrafjorour and northern Arnarfjorour is mapped. The highest marine limit is in the Nupur area, about 110 m, and shorelines and marine limits higher than 70 m are at 7 other localities at least. At least' two stages of glacial readvances are recognized: The Tjaldanes stage occurred when sea level was between 11 and 22 m and is probably of "Younger Dryas" age; later a readvance occurred in the cirques in the area. On the basis of evidence on cirque distribution, cirque elevation, zeolite zonation, distribution of glacial erosional landscapes, glacial history, marine limits, ice cap profiles and shelf moraine a model of maximum glaciations of Vestfir6ir is proposed: The whole of Vestfir6ir and the surrounding shelf areas was completely ice covered with no ice free areas. Such a stage of glaciation, the Latragrunn stage, probably prevailed in the Vestfiroir area during the last glaciation.

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (p. 99-110).