Western Canadian Association of Geographers Western Division Meeting 2009
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Transcript of Western Canadian Association of Geographers Western Division Meeting 2009
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Dendrochronologic record for mid-late Holocene glacial activity in Manatee
Valley, Upper Lillooet Provincial Park, southern Coast Mountains, BC
Lindsey E. Koehler and Dan J. SmithUniversity of Victoria Tree Ring LaboratoryDepartment of GeographyUniversity of VictoriaVictoria, BC
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Outline
Introduction to the research context Study Area Methods Results Discussion Suggestions for future research
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Historical Context for Glaciological Research in the B.C. Coast Mountains
1930’s
Early photographic records of glacier extents 1940’s
Post-WWII aerial photography 1950’s
Early applications of dendroglaciology to Little Ice Age moraines (Mathews, 1951; Brink, 1959) 1960’s
Radiometric dating applied to dendroglaciologic samples Beginning of glacier mass balance monitoring at Place Glacier
1980’s
First detailed study of Holocene glacial activity (Ryder and Thomson, 1986) 1990’s
Continued work in the Coast Mountains 2000’s
Detailed glacial reconstructions for entire Holocene Expanding network of glacial chronologies
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Study Area Geologic Setting
Coast Mountain Granitic Complex Quaternary volcanics Pleistocene glaciation
Biogeoclimatic Zones ESSF AT
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Manatee Valley
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Research Methods I
Dendroglaciology Subfossil wood
Detrital In-situ
First Colonizers Moraine crests Distal slopes
Living Trees Lateral margins Tree islands
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Research Methods II
Lichenometry Assumptions
Thalli expand at a constant rate Largest thallus on surface is the first colonizer Have surfaces of known age
Temporal Range Uncertainties
Ecesis interval Disturbance of the geomorphic surface Microclimatic factors Life history of lichen species
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Results Overview
Mid-Holocene Glacial Events 4270±60 14C years BP 3500±60 14C years BP 3430±60 14C years BP 2350±70 14C years BP
5-6 Little Ice Age moraine-building episodes Late-14th Century Continuous record from 18th-20th centuries
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Site 1: Orca Glacier Snout
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Site 2: Manatee Glacier Lateral Margin
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Site 3: Orca/Beluga Glacier Forefield
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Site 4: Manatee Glacier Forefield
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Site 5: Orca/Beluga Lateral Moraine
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Little Ice Age Moraines
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Lichenometry at Manatee Valley
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Lichenometric Dates for Moraine
Stabilization
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Moraine Dates vs. Tree-Ring-Widths
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Discussion: Holocene Advances in Manatee Valley
Mid-Holocene 4200 14C years BP event ‘Early Tiedemann’ Advance ‘Late Tiedemann’ Advance
Little Ice Age 1390’s Mid-1550’s Late-1600’s-early-1700’s Early-1800’s Late-1800’s Early-1900’s
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Suggestions for Future Research
Lichenometry More control surfaces from the southern Coast
Mountains Dendroglaciology
Tree-ring chronology development Continued collection of subfossil wood as ice front
recede Mass Balance reconstructions
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Acknowledgements