This study concerns the palaeoglaciation of the northeastern Tibetan Plateau, with emphasis on the Bayan Har Shan (Shan = Mountain) in the headwaters of Huang He (Yellow River). To reconstruct past glacier development multiple techniques, including remote sensing, field investigations, cosmogenic exposure dating, and numerical modelling have been employed. Analysis of the large-scale geomorphology indicates that glacial erosion has been dominant in the elevated mountain areas on the low-relief plateau, whereas fluvial erosion outpaces glacial erosion along the plateau margin. Landform and sediment records yield evidence for multiple local glaciations, restricted to the highest mountain areas, and a maximum glaciation beyond the mountain front. Absence of data supporting the former presence of proposed ice sheets, plateau-wide or regional, tentatively indicates that no ice sheet glaciation occurred on the northeastern Tibetan Plateau. Cosmogenic exposure dating of boulders, surface pebbles, and sediment sections in central Bayan Har Shan indicates that its record of past glaciations predates the global Last Glacial Maximum (LGM). Based on a world-wide analysis, yielding that wide age disparity within apparent exposure age datasets is most likely caused by post-glacial shielding processes, the Bayan Har Shan exposure ages constrain four periods of glaciation with minimum ages of 40-65 ka, 60-100 ka, 95-165 ka, and undetermined oldest stage. Similar to Bayan Har Shan, the plateau-wide distribution of boulders with pre-LGM exposure ages close to present-day glaciers shows that its LGM glaciers were generally not much larger than today. The results of a high resolution glacier model applied to nine regions across the plateau indicates that temperature depressions of 2-4 K are enough to expand glaciers beyond their global LGM extent, implying that during periods of Northern Hemisphere glaciation the Tibetan Plateau was not much colder than today or became exceedingly dry. / At the time of doctoral defence the following publications were unpublished and had a status as follows: Paper 4: Manuscript. Paper 5: Manuscript.

Glaciers and ice sheets covered extensive areas in the Northern Hemisphere during the last glacial period. Subsequently to the Last Glacial Maximum (LGM), they retreated rapidly and, except for Greenland and some other ice caps and glaciers, they vanished after the last glacial termination. This thesis examines the dynamics of deglacial environments by analysing the glacial geomorphological record with focus on the landforms created by glacial meltwater. The aims are (i) to evaluate the data available for mapping glacial meltwater features at the regional scale, and (ii) to demonstrate the potential of such features for regional ice retreat reconstructions in high-relief landscapes. Meltwater landforms such as ice-marginal meltwater channels, eskers, deltas and fossil glacial lake shorelines are used to infer former ice surface slope directions and successive positions of retreating ice margins. Evaluated high-resolution satellite imagery and digital elevation models reveal their potential to replace aerial photographs as the primary data for mapping glacial meltwater landforms. Following a methods study, reconstructions of the deglacial dynamics are carried out for central Transbaikalia, Siberia, Russia, and for the Cordilleran Ice Sheet (CIS) in central British Columbia, Canada, using regional geomorphological mapping surveys. Mapped glacial landforms in central Transbaikalia show evidence of a significant glaciation that possibly extended beyond the high mountain areas. Large glacial lakes were formed as advancing glaciers blocked rivers, and of these, Glacial Lake Vitim was the most prominent. Deglacial dynamics of the CIS reveals that the ice divide shifted to the Coast Mountains in north-central British Columbia and the eastern ice margin retreated towards the ice divide in late glacial time. This thesis demonstrates the potential to reconstruct ice retreat patterns and deglacial dynamics at regional scales by interpretation of the meltwater landform record. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 5: Submitted. Paper 6: Manuscript.

<p>The glacial history of the Tibetan Plateau has long been a contentious topic with widely different reconstructions. For Tanggula Shan, an extensive mountain range on the central Tibetan Plateau, multiple glacial reconstruc- tions and studies on the glacial chronology have been presented. However, the glacial geomorphological record has been sparse resulting in insufficient data to fully infer the area’s palaeoglaciology. Focussing on four landform categories, glacial valleys, marginal moraines, hummocky terrain, and glacial lineations; a glacial geomorphological map was produced, using Landsat 7 ETM+ satellite imagery, SRTM digital elevation model, and Google Earth. This map, together with GIS analyses and available cosmogenic exposure and electron spin reso- nance ages from the study area, was used to investigate the extent of former glaciations. Cosmogenic exposure and electron spin resonance ages range from 18.4 ± 1.6 to 203.4 ± 33.2 ka (recalculated using the CRONUS calculator). The extent of the glacial footprint is restricted to the high mountain areas, and is similar in extent to earlier glacial reconstructions. This glacial footprint can tentatively be explained by a monsoonal influence in the southeast, with the influence diminishing to the northwest. Alternatively, the precipitation gradient might have resulted in cold-based ice in the west and warm-based ice in the east. These variations in ice regime could have left fewer traces of glaciation in the west, than in the east. There is no evidence supporting an ice sheet covering the entire Tibetan Plateau. Rather, the available data support a smaller ice field in the high mountain areas, with a maximum extent well before the Last Glacial Maximum.</p>

The glacial history of the Tibetan Plateau has long been a contentious topic with widely different reconstructions. For Tanggula Shan, an extensive mountain range on the central Tibetan Plateau, multiple glacial reconstruc- tions and studies on the glacial chronology have been presented. However, the glacial geomorphological record has been sparse resulting in insufficient data to fully infer the area’s palaeoglaciology. Focussing on four landform categories, glacial valleys, marginal moraines, hummocky terrain, and glacial lineations; a glacial geomorphological map was produced, using Landsat 7 ETM+ satellite imagery, SRTM digital elevation model, and Google Earth. This map, together with GIS analyses and available cosmogenic exposure and electron spin reso- nance ages from the study area, was used to investigate the extent of former glaciations. Cosmogenic exposure and electron spin resonance ages range from 18.4 ± 1.6 to 203.4 ± 33.2 ka (recalculated using the CRONUS calculator). The extent of the glacial footprint is restricted to the high mountain areas, and is similar in extent to earlier glacial reconstructions. This glacial footprint can tentatively be explained by a monsoonal influence in the southeast, with the influence diminishing to the northwest. Alternatively, the precipitation gradient might have resulted in cold-based ice in the west and warm-based ice in the east. These variations in ice regime could have left fewer traces of glaciation in the west, than in the east. There is no evidence supporting an ice sheet covering the entire Tibetan Plateau. Rather, the available data support a smaller ice field in the high mountain areas, with a maximum extent well before the Last Glacial Maximum.

<p>This thesis presents a palaeoglaciological study aimed to determine the location, geometry and temporal evolution of palaeo-ice streams of the north-easternmost Laurentide Ice Sheet. The work was accomplished through the geomorphological interpretation of satellite imagery over 3.19 x 10⁶ km² of the Canadian Arctic, using a glaciological inversion scheme. Ice streams were active in this region during most of the time between the Last Glacial Maximum and the last deglaciation. A web of ice streams and inter-ice stream areas existed. Three major ice stream networks are identified: the M'Clintock Channel, Gulf of Boothia – Lancaster Sound and Hudson Strait. The M'Clintock Channel bears the most complex landform record, comprising three generations of palaeo-ice streams. Their location was weakly controlled by the subglacial topography and their geometry was determined by frozen-bed portions of the ice sheet, thus providing evidence for pure ice streams in the Laurentide Ice Sheet. In contrast, the more pronounced relief of the Gulf of Boothia – Lancaster Sound corridor supported topographically controlled ice streams. The landform record on emerged land along Hudson Strait is insufficient to support the existence of ice streams. It is therefore proposed that ice streams were constrained within the deep parts of the strait while flanked by cold-based zones on the margins. Small transient ice streams on Baffin and Prince of Wales islands drained local remnant ice caps during the collapse of the ice sheet. Analysis of the controls on the location and flow of palaeo-ice streams suggests that the interaction between the subglacial topography and thermal state of the substrate plays a more fundamental role than the geology. It is concluded that the behaviour of ice streams cannot be explained in terms of environmental controls alone, but the complex dynamics of ice stream shear margins and onset zones must be considered.</p>

This thesis presents a palaeoglaciological study aimed to determine the location, geometry and temporal evolution of palaeo-ice streams of the north-easternmost Laurentide Ice Sheet. The work was accomplished through the geomorphological interpretation of satellite imagery over 3.19 x 106 km2 of the Canadian Arctic, using a glaciological inversion scheme. Ice streams were active in this region during most of the time between the Last Glacial Maximum and the last deglaciation. A web of ice streams and inter-ice stream areas existed. Three major ice stream networks are identified: the M'Clintock Channel, Gulf of Boothia – Lancaster Sound and Hudson Strait. The M'Clintock Channel bears the most complex landform record, comprising three generations of palaeo-ice streams. Their location was weakly controlled by the subglacial topography and their geometry was determined by frozen-bed portions of the ice sheet, thus providing evidence for pure ice streams in the Laurentide Ice Sheet. In contrast, the more pronounced relief of the Gulf of Boothia – Lancaster Sound corridor supported topographically controlled ice streams. The landform record on emerged land along Hudson Strait is insufficient to support the existence of ice streams. It is therefore proposed that ice streams were constrained within the deep parts of the strait while flanked by cold-based zones on the margins. Small transient ice streams on Baffin and Prince of Wales islands drained local remnant ice caps during the collapse of the ice sheet. Analysis of the controls on the location and flow of palaeo-ice streams suggests that the interaction between the subglacial topography and thermal state of the substrate plays a more fundamental role than the geology. It is concluded that the behaviour of ice streams cannot be explained in terms of environmental controls alone, but the complex dynamics of ice stream shear margins and onset zones must be considered.