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M. Motta - One of the best experts on this subject based on the ideXlab platform.
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dry calving processes at the ice cliff of Strandline glacier northern victoria land antarctica
Annals of Glaciology, 2004Co-Authors: G. Diolaiuti, C. Smiraglia, G. Vassena, M. MottaAbstract:This paper describes seasonal variations on Strandline Glacier, Terra Nova Bay, northern Victoria Land, Antarctica, obtained from measurements during two field campaigns (2000/01 and 2002/03). By applying different methodologies and techniques, it was possible to calculate summer changes in thickness (mean decrease over the whole glacier surface of 0.04 mw.e.) and in volume (decrease of 352 μ3 at the terminus). This serves to identify and quantify the processes responsible for these variations (e.g. melting, evaporation, wind erosion/deposition and calving) and to understand the energy transfers at the glacier–air interface. One particular feature of the glacier is the presence of an ice cliff at the terminus, which causes ablation owing to dry calving. This process brought about a summer retreat rate of 1 mweek–1 in the central part of the front during the study period. Qualitative observations carried out during previous field campaigns and quantitative analysis performed during the last two expeditions have provided an understanding of the mechanism underlying the ablation processes, thus confirming the available literature on this topic.
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Dry calving processes at the ice cliff of Strandline Glacier, northern Victoria Land
'International Glaciological Society', 2004Co-Authors: G. Diolaiuti, C. Smiraglia, G. Vassena, M. MottaAbstract:This paper describes seasonal variations on Strandline Glacier, Terra Nova Bay, northern Victoria Land, Antarctica, obtained from measurements during two field campaigns (2000/01 and 2002/03). By applying different methodologies and techniques, it was possible to calculate summer changes in thickness (mean decrease over the whole glacier surface of 0.04mw.e.) and in volume (decrease of 352m3 at the terminus). This serves to identify and quantify the processes responsible for these variations (e.g. melting, evaporation, wind erosion/deposition and calving) and to understand the energy transfers at the glacier\u2013air interface. One particular feature of the glacier is the presence of an ice cliff at the terminus, which causes ablation owing to dry calving. This process brought about a summer retreat rate of 1mweek\u20131 in the central part of the front during the study period. Qualitative observations carried out during previous field campaigns and quantitative analysis performed during the last two expeditions have provided an understanding of the mechanism underlying the ablation processes, thus confirming the available literature on this topic
Timothy G. Fisher - One of the best experts on this subject based on the ideXlab platform.
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determining the lake agassiz moorhead phase lowstand elevation from compaction ridges and newly identified Strandlines in the red river valley usa
Geomorphology, 2018Co-Authors: John Dilworth, Timothy G. FisherAbstract:Abstract A variety of low-relief and subtle landforms mapped from high-resolution, hill-shaded DEMs are used to assign a lower limit to the poorly constrained lowstand elevation of the Moorhead Phase of glacial Lake Agassiz. Downstream ends of compaction ridges (low-relief ridges that trace former stream channels) and weakly developed scarps on either side of the valley at ~247 m are used to provide a best estimate for a lowstand elevation based on geomorphology. Compaction ridges are often sinuous, oriented congruent with modern hydrology, cross-cut younger Strandlines, sometimes end at deltas, and formed as a result of delayed greater subsidence of finer-grained sediment than coarser-grained sediment. Previously unmapped, abandoned stream channels of similar scale to compaction ridges are restricted to zones south of Fargo and in places transition downstream into compaction ridges. Many abandoned channels are linear and not occupied by modern streams. Further north, iceberg scours increase in density in lowland areas adjacent to the Red River of the North, where they cross-cut newly identified, low-relief scarps interpreted as erosional scarp Strandlines. The 1–2 m relief scarps are currently the strongest geomorphic evidence for the lowest level of the Moorhead Phase of Lake Agassiz.
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a chronology for glacial lake agassiz shorelines along upham s namesake transect
Quaternary Research, 2013Co-Authors: Kenneth Lepper, Alex W Buell, Timothy G. Fisher, Thomas V. LowellAbstract:Abstract Four traditionally recognized Strandline complexes in the southern basin of glacial Lake Agassiz are the Herman, Norcross, Tintah and Campbell, whose names correspond to towns in west-central Minnesota that lie on a linear transect defined by the Great Northern railroad grade; the active corridor for commerce at the time when Warren Upham was mapping and naming the shorelines of Lake Agassiz (ca.1880–1895). Because shorelines represent static water planes, their extension around the lake margin establishes time-synchronous lake levels. Transitions between shoreline positions represent significant water-level fluctuations. However, geologic ages have never been obtained from sites near the namesake towns in the vicinity of the southern outlet. Here we report the first geologic ages for Lake Agassiz shorelines obtained at field sites along the namesake transect, and evaluate the emerging chronology in light of other paleoclimate records. Our current work from 11 sampling sites has yielded 16 independent ages. These results combined with a growing OSL age data set for Lake Agassiz's southern basin provide robust age constraints for the Herman, Norcross and Campbell Strandlines with averages and standard deviations of 14.1 ± 0.3 ka, 13.6 ± 0.2 ka, and 10.5 ± 0.3 ka, respectively.
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Testing northwest drainage from Lake Agassiz using extant ice margin and Strandline data
Quaternary International, 2012Co-Authors: Timothy G. Fisher, Thomas V. LowellAbstract:Extant data on shorelines and ice margins in the glacial Lake Agassiz basin defines the limits of Lake Agassiz through deglacial time. The ice sheet margin had not retreated far enough northwards by the beginning or end of the Younger Dryas chronozone for the lake to drain northwest. However, once Lake Agassiz reached the Campbell Beach stage at ∼10,800–10,300 cal BP, then projections of Lake Agassiz Strandlines were higher than the topography allowing for the first possible pathway to the northwest. This relationship is used to reject the recent assertion that there was northwest drainage from Lake Agassiz at the beginning and end of the Younger Dryas chronozone.
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Strandline analysis in the southern basin of glacial lake agassiz minnesota and north and south dakota usa
Geological Society of America Bulletin, 2005Co-Authors: Timothy G. FisherAbstract:Glacial Lake Agassiz, a large Pleistocene lake, left behind Strandlines at multiple elevations within its basin. Prior researchers have used these Strandlines to identify four relatively stable water level stages, but tracing them over long distances is often problematic. In this study, the elevation of the Tintah Strandline is returned to its original designation, and a newly interpreted stable lake level at 1020–1030 ft (311–314 m) is referred to as the Upham level, based on a concentration of ridges and a spit at that elevation. Cores from Strandline and lagoon complexes from the Milnor to Tintah beaches reveal a decreasing thickness of Strandline sediment associated with shorter aggregate-length Strandlines. This relationship is most likely controlled by sediment starvation, greater water level fluctuations and shallower water. Beaches near the head of the southern outlet spillway indicate that shoreline occupation at the Lower Campbell level was either very short-lived or Strandline development was hampered by shallow water. The modern-day sill elevation between the southern outlet spillway and the lake basin is found to be 3 km south of White Rock, Minnesota, at an elevation of 974 ft (297 m). All but the Campbell Strandlines at the southern outlet are interpreted as the result of a regression driven by incision of the southern outlet spillway.
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glacial lake agassiz its northwest maximum extent and outlet in saskatchewan emerson phase
Quaternary Science Reviews, 1994Co-Authors: Timothy G. Fisher, Derald G SmithAbstract:Abstract Six different lines of evidence support the hypothesis that glacial Lake Agassiz expanded an additional 70,000 km2 over that previously mapped in northwestern Saskatchewan and that the lake discharged out the northwestern (Clearwater) outlet, then through glacial Lake McConnell and Mackenzie River to the Arctic Ocean. Elevations of formerly unmapped (1) Strandlines and (2) glaciolacustrine sediments between the previously mapped northwest limit of Lake Agassiz and the Clearwater-lower Athabasca spillway indicate that water extended 170 km farther northwest. Recently, mapped Strandlines at elevations up to 60 m above the previously mapped extent of Lake Agassiz can be traced along (3) isobases to the mouth of the spillway. Based upon (4) six radiocarbon dates recovered from spillway flood deposits in the Athabasca River valley and its late Pleistocene delta, the (5) Clearwater spillway was cut at 9.9 ka BP. This date is synchronous with the initiation of the Emerson Phase (9.9 ka BP) in the southern Lake Agassiz basin and (6) coincides with the position of the Laurentide Ice Sheet at the Cree Lake Moraine (10 ka BP) along the northern margin of the lake. Following closure of the eastern outlets at the onset of the Emerson Phase, Lake Agassiz transgressed toward the northwest into the deglaciated and isostatically depressed glacial foreland in the Churchill River valley to an elevation of 490 m, the pre-flood elevation of the Churchill-Mackenzie drainage divide at the head of the Clearwater-lower Athabasca spillway. The Beaver River Moraine (an earthen drainage divide) was breached, resulting in lowering Lake Agassiz 52 m to a stable elevation at 438 m. The lake discharged 21,000 km3 of water into the Arctic Ocean that raised global sea level by 6 cm.
G. Diolaiuti - One of the best experts on this subject based on the ideXlab platform.
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dry calving processes at the ice cliff of Strandline glacier northern victoria land antarctica
Annals of Glaciology, 2004Co-Authors: G. Diolaiuti, C. Smiraglia, G. Vassena, M. MottaAbstract:This paper describes seasonal variations on Strandline Glacier, Terra Nova Bay, northern Victoria Land, Antarctica, obtained from measurements during two field campaigns (2000/01 and 2002/03). By applying different methodologies and techniques, it was possible to calculate summer changes in thickness (mean decrease over the whole glacier surface of 0.04 mw.e.) and in volume (decrease of 352 μ3 at the terminus). This serves to identify and quantify the processes responsible for these variations (e.g. melting, evaporation, wind erosion/deposition and calving) and to understand the energy transfers at the glacier–air interface. One particular feature of the glacier is the presence of an ice cliff at the terminus, which causes ablation owing to dry calving. This process brought about a summer retreat rate of 1 mweek–1 in the central part of the front during the study period. Qualitative observations carried out during previous field campaigns and quantitative analysis performed during the last two expeditions have provided an understanding of the mechanism underlying the ablation processes, thus confirming the available literature on this topic.
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Dry calving processes at the ice cliff of Strandline Glacier, northern Victoria Land
'International Glaciological Society', 2004Co-Authors: G. Diolaiuti, C. Smiraglia, G. Vassena, M. MottaAbstract:This paper describes seasonal variations on Strandline Glacier, Terra Nova Bay, northern Victoria Land, Antarctica, obtained from measurements during two field campaigns (2000/01 and 2002/03). By applying different methodologies and techniques, it was possible to calculate summer changes in thickness (mean decrease over the whole glacier surface of 0.04mw.e.) and in volume (decrease of 352m3 at the terminus). This serves to identify and quantify the processes responsible for these variations (e.g. melting, evaporation, wind erosion/deposition and calving) and to understand the energy transfers at the glacier\u2013air interface. One particular feature of the glacier is the presence of an ice cliff at the terminus, which causes ablation owing to dry calving. This process brought about a summer retreat rate of 1mweek\u20131 in the central part of the front during the study period. Qualitative observations carried out during previous field campaigns and quantitative analysis performed during the last two expeditions have provided an understanding of the mechanism underlying the ablation processes, thus confirming the available literature on this topic
C. Smiraglia - One of the best experts on this subject based on the ideXlab platform.
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dry calving processes at the ice cliff of Strandline glacier northern victoria land antarctica
Annals of Glaciology, 2004Co-Authors: G. Diolaiuti, C. Smiraglia, G. Vassena, M. MottaAbstract:This paper describes seasonal variations on Strandline Glacier, Terra Nova Bay, northern Victoria Land, Antarctica, obtained from measurements during two field campaigns (2000/01 and 2002/03). By applying different methodologies and techniques, it was possible to calculate summer changes in thickness (mean decrease over the whole glacier surface of 0.04 mw.e.) and in volume (decrease of 352 μ3 at the terminus). This serves to identify and quantify the processes responsible for these variations (e.g. melting, evaporation, wind erosion/deposition and calving) and to understand the energy transfers at the glacier–air interface. One particular feature of the glacier is the presence of an ice cliff at the terminus, which causes ablation owing to dry calving. This process brought about a summer retreat rate of 1 mweek–1 in the central part of the front during the study period. Qualitative observations carried out during previous field campaigns and quantitative analysis performed during the last two expeditions have provided an understanding of the mechanism underlying the ablation processes, thus confirming the available literature on this topic.
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Dry calving processes at the ice cliff of Strandline Glacier, northern Victoria Land
'International Glaciological Society', 2004Co-Authors: G. Diolaiuti, C. Smiraglia, G. Vassena, M. MottaAbstract:This paper describes seasonal variations on Strandline Glacier, Terra Nova Bay, northern Victoria Land, Antarctica, obtained from measurements during two field campaigns (2000/01 and 2002/03). By applying different methodologies and techniques, it was possible to calculate summer changes in thickness (mean decrease over the whole glacier surface of 0.04mw.e.) and in volume (decrease of 352m3 at the terminus). This serves to identify and quantify the processes responsible for these variations (e.g. melting, evaporation, wind erosion/deposition and calving) and to understand the energy transfers at the glacier\u2013air interface. One particular feature of the glacier is the presence of an ice cliff at the terminus, which causes ablation owing to dry calving. This process brought about a summer retreat rate of 1mweek\u20131 in the central part of the front during the study period. Qualitative observations carried out during previous field campaigns and quantitative analysis performed during the last two expeditions have provided an understanding of the mechanism underlying the ablation processes, thus confirming the available literature on this topic
G. Vassena - One of the best experts on this subject based on the ideXlab platform.
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dry calving processes at the ice cliff of Strandline glacier northern victoria land antarctica
Annals of Glaciology, 2004Co-Authors: G. Diolaiuti, C. Smiraglia, G. Vassena, M. MottaAbstract:This paper describes seasonal variations on Strandline Glacier, Terra Nova Bay, northern Victoria Land, Antarctica, obtained from measurements during two field campaigns (2000/01 and 2002/03). By applying different methodologies and techniques, it was possible to calculate summer changes in thickness (mean decrease over the whole glacier surface of 0.04 mw.e.) and in volume (decrease of 352 μ3 at the terminus). This serves to identify and quantify the processes responsible for these variations (e.g. melting, evaporation, wind erosion/deposition and calving) and to understand the energy transfers at the glacier–air interface. One particular feature of the glacier is the presence of an ice cliff at the terminus, which causes ablation owing to dry calving. This process brought about a summer retreat rate of 1 mweek–1 in the central part of the front during the study period. Qualitative observations carried out during previous field campaigns and quantitative analysis performed during the last two expeditions have provided an understanding of the mechanism underlying the ablation processes, thus confirming the available literature on this topic.
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Dry calving processes at the ice cliff of Strandline Glacier, northern Victoria Land
'International Glaciological Society', 2004Co-Authors: G. Diolaiuti, C. Smiraglia, G. Vassena, M. MottaAbstract:This paper describes seasonal variations on Strandline Glacier, Terra Nova Bay, northern Victoria Land, Antarctica, obtained from measurements during two field campaigns (2000/01 and 2002/03). By applying different methodologies and techniques, it was possible to calculate summer changes in thickness (mean decrease over the whole glacier surface of 0.04mw.e.) and in volume (decrease of 352m3 at the terminus). This serves to identify and quantify the processes responsible for these variations (e.g. melting, evaporation, wind erosion/deposition and calving) and to understand the energy transfers at the glacier\u2013air interface. One particular feature of the glacier is the presence of an ice cliff at the terminus, which causes ablation owing to dry calving. This process brought about a summer retreat rate of 1mweek\u20131 in the central part of the front during the study period. Qualitative observations carried out during previous field campaigns and quantitative analysis performed during the last two expeditions have provided an understanding of the mechanism underlying the ablation processes, thus confirming the available literature on this topic
