Little Ice Age glacial activity in the Mt. Waddington area, British Columbia Coast Mountains, Canada
The establishment of fourteen Little Ice Age (LIA) glacier chronologies in the Mt. Waddington area led to the development of an extended history of glacial activity in this portion of the southern British Columbia Coast Mountains, Canada. The glaciers were located within four different mountain ranges, and were of varying size and aspect. Dendrochronological and lichenometric techniques were used to provide relative age estimates of moraines formed as glacier termini retreated from advanced positions. Evidence for pre-LIA glacial events is best preserved at Tiedemann Glacier, where the oldest glacial advances date to A.D. 620 and 925-933. Soil-covered and well-vegetated moraines built at Cathedral, Pagoda, and Siva glaciers date to between A.D. 1203 and 1226. Following this event, moraines constructed at Ragnarok, Siva, and Cathedral glaciers in the mid-14th century suggest glaciers in the region underwent a period of downwasting and retreat before readvancing. The majority of moraines recorded in the Mt. Waddington area describe late-LIA glacial events shown to have constructed moraines that date to A.D. 1443-1458, 1506-1524, 1562-1575, 1597-1621, 1657-1660, 1767-1784, 1821-1837, 1871-1900, 1915-1928, and 1942-1946. Over the last 500 years, these moraine-building episodes were shown to occur on average every 65 years and suggest there has been prolonged synchronicity in the glaciological response to persistent climate-forcing mechanisms. Nevertheless, our analysis suggests that local factors, such as aspect and size, play an important role in individual glacial response. Notably, ice termini of medium-size glaciers facing eastwards showed a quicker response to climatically induced mass balance changes. Resume : L'historique de quatorze glaciers de vallee de la region du mont Waddington, sud de la Chaine Cotiere de Colombie-Britannique, Canada, durant le Petit Âge Glaciaire (PAG) fut evalue par l'utilisation de techniques dendrochronologiques et lichenometriques, procurant un âge minimum pour la formation des moraines laterales et frontales multiples. Les glaciers a l'etude, d'aspect et de taille differents, furent selectionnes a partir de quatre chaines de montagnes. Les evenements qui predatent le PAG sont le mieux preserves sur le site du glacier Tiedemann, ou les plus vieilles avancees glaciaires date de A.D. 620 et 925-933. Des moraines presentant une pedogenese avancee et recouvertes d'une dense couverture vegetale furent datees entre A.D. 1203 et 1226. Des moraines construites dans le milieu du 14 e siecle par les glaciers Ragnarok, Siva et Cathedral suggerent que les glaciers de la region se sont retires pour par la suite reavancer. La majorite des moraines datees le furent vers la fin du PAG, soit en A.D. 1443-1458, 1506-1524, 1562-1575, 1597-1621, 1657-1660, 1767-1784, 1821-1837, 1871-1900, 1915-1928 et 1942-1946. Au cours des 500 dernieres annees, en moyenne 65 annees separent les differents episodes glaciaires, ce qui suggerent un synchronisme des reponses glaciaires aux mecanismes climatiques. Des donnees preliminaires suggerent que l'orientation et la taille des glaciers jouent un role important dans la reponse individualiste des glaciers. En fait, les terminus glaciaires des moyens glaciers d'orientation est semblent repondre plus rapidement a un ajustement de volume interne glaciaire.