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Postglacial water levels in the Great Lakes Region in relation to Holocene climate change : Thecamoebian and Palynological evidence /

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dc.contributor.author Sarvis, Adam Patrick. en_US
dc.date.accessioned 2009-07-14T19:40:53Z
dc.date.available 2009-07-14T19:40:53Z
dc.date.issued 2000-07-14T19:40:53Z
dc.identifier.uri http://hdl.handle.net/10464/2266
dc.description.abstract Various lake phases have developed in the upper Great Lakes in response to isostatic adjustment and changes in water supply since the retreat of the Laurentide Ice Sheet. Georgian Bay experienced a lowstand that caused a basin wide unconformity approximately 7,500 years ago that cannot be explained by geological events. Thecamoebians are shelled protozoans abundant in freshwater environments and they are generally more sensitive to changing environmental conditions than the surrounding vegetation. Thecamoebians can be used to reconstruct the paleolimnology. The abundance of thecamoebians belonging to the genus Centropyxis, which are known to tolerate slightly brackish conditions (i.e. high concentrations of ions) records highly evaporative conditions in a closed basin. During the warmer interval (9000 to 700 yBP), the Centropyxis - dominated population diminishes and is replaced by an abundant and diverse Difflugia dominate population. Historical climate records from Tobermory and Midland, Ontario were correlated with the Lake Huron water level curve. The fossil pollen record and comparison with modem analogues allowed a paleo-water budget to be calculated for Georgian Bay. Transfer function analysis of fossil pollen data from Georgian Bay records cold, dry winters similar to modem day Minneapolis, Minnesota. Drier climates around this time are also recorded in bog environments in Southem Ontario - the drying of Lake Tonawanda and inception of paludification in Willoughby Bog, for instance, dates around 7,000 years ago. The dramatic impact of climate change on the water level in Georgian Bay underlines the importance of paleoclimatic research for predicting future environmental change in the Great Lakes. en_US
dc.language.iso eng en_US
dc.publisher Brock University en_US
dc.subject Water levels en_US
dc.subject Water levels en_US
dc.subject Water levels en_US
dc.subject Paleoclimatology en_US
dc.subject Paleoclimatology en_US
dc.subject Paleoclimatology en_US
dc.subject Climatic changes en_US
dc.subject Climatic changes en_US
dc.title Postglacial water levels in the Great Lakes Region in relation to Holocene climate change : Thecamoebian and Palynological evidence / en_US
dc.type Electronic Thesis or Dissertation en_US
dc.degree.name M.Sc. Earth Sciences en_US
dc.degree.level Masters en_US
dc.contributor.department Department of Earth Sciences en_US
dc.degree.discipline Faculty of Mathematics and Science en_US


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