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dc.contributor.authorSarvis, Adam Patrick.en_US
dc.date.accessioned2009-07-14T19:40:53Z
dc.date.available2009-07-14T19:40:53Z
dc.date.issued2000-07-14T19:40:53Z
dc.identifier.urihttp://hdl.handle.net/10464/2266
dc.description.abstractVarious 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.isoengen_US
dc.publisherBrock Universityen_US
dc.subjectWater levelsen_US
dc.subjectWater levelsen_US
dc.subjectWater levelsen_US
dc.subjectPaleoclimatologyen_US
dc.subjectPaleoclimatologyen_US
dc.subjectPaleoclimatologyen_US
dc.subjectClimatic changesen_US
dc.subjectClimatic changesen_US
dc.titlePostglacial water levels in the Great Lakes Region in relation to Holocene climate change : Thecamoebian and Palynological evidence /en_US
dc.typeElectronic Thesis or Dissertationen_US
dc.degree.nameM.Sc. Earth Sciencesen_US
dc.degree.levelMastersen_US
dc.contributor.departmentDepartment of Earth Sciencesen_US
dc.degree.disciplineFaculty of Mathematics and Scienceen_US


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