HR: 0800h
AN: H51C-0391    [Abstracts]
TI: Palaeoshoreline evidence for glacial megalakes in the McMurdo Dry Valleys, Antarctica: Glacial Lake Victoria reappraised
AU: * Neil, D
EM: d.neil@uq.edu.au
AF: School of Geography, Planning and Architecture, The University of Queensland, Brisbane, QLD 4072 Australia
AU: McGowan, H
EM: h.mcgowan@uq.edu.au
AF: School of Geography, Planning and Architecture, The University of Queensland, Brisbane, QLD 4072 Australia
AU: Dowideit, G
EM: g.dowideit@uq.edu.au
AF: School of Geography, Planning and Architecture, The University of Queensland, Brisbane, QLD 4072 Australia
AU: Speirs, J
EM: s4008355@student.uq.edu.au
AF: School of Geography, Planning and Architecture, The University of Queensland, Brisbane, QLD 4072 Australia
AU: Orwin, J
EM: jorwin@sfu.ca
AF: Department of Earth Sciences, Simon Fraser University, Burnaby, BC V5A 1S6 Canada
AB: Extensive glacial lakes have been postulated for several valleys (eg. Wright, Taylor, Victoria) in the McMurdo Dry Valleys region of Antarctica. These postulations rely on both proposed conditions and mechanisms (cool, dry, sunny, snowless, high absorption of solar radiation, high meltwater production) and field evidence (algal mats, deltaic landforms, lacustrine sediments, palaeoshorelines). Glacial Lake Victoria is such a postulated lake of c. 100km2 area, 200m depth which existed from c. 20000 - 8600 BP in the Victoria Valley. We reassess the palaeoshoreline evidence for the existence of this lake using field investigations of valley morphology, topographic survey, and analysis of LIDAR data. Given the aridity of the Dry Valleys region, good preservation of palaeoshorelines would be expected. However, our observations indicate that postulated shorelines of the Lower Victoria Valley are not continuous but spatially restricted, not flat, not horizontal, and not sub-parallel. Rather, the postulated shorelines lie across the contours, are associated with a much larger geomorphic feature and do not occur on adjacent sections of valley walls. Their morphology is consistent with slump deposits from mass movement in the form of large-scale slump failure/s of the valley wall. On the basis of this reappraisal of the postulated palaeoshorelines of the Lower Victoria Valley, the evidence, as distinct from the mechanism, for Glacial Lake Victoria appears weak. It also suggests the need for a reassessment of the palaeoshoreline evidence for glacial lakes in other valleys in the region.
DE: 1815 Erosion
DE: 1824 Geomorphology: general (1625)
DE: 1827 Glaciology (0736, 0776, 1863)
DE: 9310 Antarctica (4207)
SC: Hydrology [H]
MN: Fall Meeting 2005