Little Ice Age glacial activity in Strathcona Provincial Park, Vancouver Island, British Columbia, Canada

Abstract

Dendroglaciological and lichenometric techniques are used to establish the Little Ice Age (LIA) history of two glaciers (Colonel Foster and Septimus) in Strathcona Provincial Park, Vancouver Island, British Columbia. Our lichenometric investigations were preceded by the development of a locally calibrated Rhizocarpon geographicum growth curve (1708-1998 A.D.). Documentation of a 3-4-year ecesis interval for both trees and lichen greatly reduces one of the main uncertainties in using geobotanical methods for dating LIA landforms. The moraine dates provided, therefore, give a good approximation of the shift in climate conditions that lead to the retreat of the glaciers and subsequent moraine stabilization. Geobotanical evidence records three synchronous episodes of LIA moraine deposition at both glaciers: two prominent moraines at each site are dated to the early 1700s and late 1800s, with a third, smaller moraine dated to the mid 1930s. Moraines deposited prior to 1397 A.D. were also recorded at Colonel Foster Glacier; however, precise dating of these moraines was not possible. The moraine records from Strathcona Provincial Park suggest two possible modes of glacier response: (i) synchronous responses to larger-scale climatic forcing, and (ii) asynchronous responses to local factors such as microclimate, topography, and glacier geometry. The Vancouver Island LIA record was evaluated in the context of LIA results from the Pacific North American (PNA) Cordillera. It compares well with regional moraine records from coastal British Columbia, Washington, Alaska, and the Canadian Rocky Mountains, suggesting a regional response of PNA glaciers to climate change associated with the LIA.Résumé : Des techniques dendroglaciologiques et lichénométriques sont utilisées pour établir l'historique du Petit Âge Glaciaire de deux glaciers (Colonel Foster et Septimus) dans le parc provincial Strathcona, sur l'île de Vancouver, Colombie-Britannique. Nos études lichénométriques ont été effectuées après le développement d'une courbe de croissance de Rhizocarpon geographicum (1708 à 1998) calibrée localement. La documentation d'un intervalle écésis de 3-4 ans, à la fois pour les arbres et pour les lichens, réduit grandement les principales incertitudes quant à l'utilisation de méthodes géobotaniques pour dater les formes de relief du Petit Âge Glaciaire. Les dates de la moraine fournissent donc une bonne approximation du décalage des conditions climatiques qui a conduit au retrait des glaciers et à la stabilisation subséquente des moraines. Les évidences géobotaniques documentent trois épisodes synchrones de déposition de moraine du Petit Âge Glaciaire aux deux glaciers : deux moraines proéminentes à chaque site ont été datées du début des années 1700 et de la fin des années 1800; une troisième moraine, plus petite, date du milieu des années 1930. Des moraines déposées avant 1397 sont aussi enregistrées au glacier Colonel Foster; toutefois, il n'a pas été possible de dater ces moraines avec précision. Les évidences contenues dans les m...

Glacier change in Garibaldi Provincial Park, southern Coast Mountains, British Columbia, since the Little Ice Age

“…Glaciers were stable or advanced up to 1000 m between the 1950s and early 1980s (Baranowski and Henoch, 1978), but since then have retreated, with length losses of up to 500 m (Kershaw et al, 2005) and average thinning rates of about 0.53-0.89 m/a (Schiefer et al, 2007). Total loss in ice cover since the Little Ice Age differs from glacier to glacier, with reported values ranging from 10 to 90% (McCarthy and Smith, 1994;Luckman, 1998;Lewis and Smith, 2004a).…”

Dendrogeomorphic reconstruction of Little Ice Age paraglacial activity in the vicinity of the Homathko Icefield, British Columbia Coast Mountains, Canada

“…This observation suggests that this event may have been short lived. Moraines elsewhere in the region stabilized shortly after this time, in the mid to late 1660s (Larocque and Smith, 2003;Lewis and Smith, 2004).…”

“…7). This time period is widely recognized as one when glaciers were advancing throughout the southern Coast Mountains (Ryder and Thomson, 1986;Larocque and Smith, 2003;Lewis and Smith, 2004;Allen and Smith, 2007;Koch et al, 2007).…”

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