Melt Regimes, Internal Stratigraphy, and Flow Dynamics of Three Glaciers in the Alaska Range
Mountain and alpine valley glaciers are often described by their thermal characteristics, which, in turn, are heavily influenced by environmental factors such as latitude and elevation, amongst others. Low elevation and/or low latitude glaciers that experience melting throughout the snow pack are in...
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DigitalCommons@UMaine
2010
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| Online Access: | https://digitalcommons.library.umaine.edu/etd/773 https://digitalcommons.library.umaine.edu/context/etd/article/1771/viewcontent/CampbellSW2010.pdf |
| Summary: | Mountain and alpine valley glaciers are often described by their thermal characteristics, which, in turn, are heavily influenced by environmental factors such as latitude and elevation, amongst others. Low elevation and/or low latitude glaciers that experience melting throughout the snow pack are in the wet zone. Whereas glaciers at higher elevations and/or higher latitudes that experience some melting and refreezing, or no melting, are in the percolation and dry zones, respectively. Defining boundary elevations between these melt regimes is a fundamental step to determine where melting occurs, both locally (glacier scale) and regionally (mountain range scale). Secondly, ice cores, a primary source of paleoclimate information, require glacier ice which has experienced minimal melting and deformation. Herein, I use ground penetrating radar (GPR), geodetic, and glaciochemical evidence collected on three glaciers from the Alaska Range, to estimate regional melt regime boundary elevations. I simultaneously use the same evidence to assess englacial stratigraphy and flow dynamics of the three glaciers and make recommendations for potential ice core drill sites based on pre-determined drilling criteria. Glaciochemical and snow pit stratigraphy collected at Kahiltna Pass Basin on Mount McKinley (3100 masl) show evidence of some melt and refreezing in the snow pack and firn suggesting this site is in the upper region of the percolation zone. Radar profiles and surface velocity data show a maximum depth of 300 meters in the basin and westward dipping englacial stratigraphy that experienced vertical thickening as it flowed from a steep, narrow, and high velocity valley into a flat, wide basin in which velocities were slower. Stratigraphy on the western side of this basin is surface conformable, but likely experiences some fanning and thinning due to the increasing basin dimensions relative to the narrow valley, up-glacier. Radar profiles show that isochronal integrity is preserved and mostly continuous within the upper ... |
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