Late Holocene glacial activity of Bridge Glacier, British Columbia coast mountains




Allen, Sandra Michele

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Bridge Glacier is a prominent eastward-flowing valley glacier located on the east side of the Pacific Ranges within the southern British Columbia Coast Mountains. The terminus of Bridge Glacier has retreated at rates ranging from 0 to 125 m/year over the last 50 years and currently calves into proglacial Bridge Lake. Field investigations of the recently deglaciated terrain at Bridge Glacier in 2002 and 2003 led to the discovery of detrital boles and glacially-sheared stumps. Dendroglaciological analyses of this subfossil wood allowed for the construction of five radiocarbon-controlled floating tree-ring chronologies. The relative age and stratigraphic location of these samples revealed that Bridge Glacier experienced at least four periods of significant advance during the late Holocene: a Tiedemann-aged advance at ca. 3000'4C years BP. an unattributed advance at ca. 1900 '4C years BP. a First Millennial Advance at ca. 1500 '4C years BP. and an early Little Ice Age advance at ca. 700 '4C years BP. Lichenometric investigations at eight terminal and lateral moraine complexes led to the recognition of early Little Ice Age moraine-building events during the late 13th to early 14th centuries. with subsequent Little Ice Age episodes in the mid 15th. early 16th. mid-late 17th, early 18th, mid-late 19th, and early 20th centuries. These interpretations provide an exceptional long-term perspective on the extent and character of a glacier within this region during the late Holocene.



glaciers, history, British Columbia