Author : Harvey, J.E. Date : 2011. Title : -Holocene glacier activity in the central British Columbia Coast Mountains. Publication : Unpublished MSc thesis. University of Victoria, Victoria, British Columbia. Issue : Page(s) : 81 p.
The purpose of the research described in this thesis was to reconstruct anddocument Holocene glacier activity, and to describe late-Little Ice Age climates in the central Coast Mountains. In Pacific North America an increasingly complex chronology of glacial activity is emerging that is largely constrained to six periods of climate change at 9000–8000, 6000–5000, 4200–3800, 3500–2500, 1200–1000, and 600–150 ka. The application of dendroglaciological, lichenometric and dendroclimatological research techniques applied in the British Columbia Coast Mountains region has provided substantive insights into Holocene glacier activity and Little Ice Age climates. Fieldwork conducted in 2010 in the central Coast Mountains yielded mid-Holocene aged deposits at Jacobsen Glacier, and the scope of these investigations expanded to include analysis of previously unreported dendroglaciological samples from Fyles (2002), Tchaikazan (2002), Canoe (2006) and Icemaker (2006) glaciers. Evidence from these 5 glacier sites documents an interval of glacial expansion between 7.5 and 4.0 ka previously unrecorded in the central and northern Coast Mountains. Within this interval discrete glaciers advances began prior to 6.63, 4.9 and 4.2 ka, indicating that mid-Holocene climates were more varied than often described. Little Ice Age moraine building episodes at Pattullo, Fyles, Deer Lake and Jacobsen glaciers in the central Coast Mountains were identified using lichenometric and dendroglaciological research techniques. Dominant periods of moraine building at 892-1023, 1283-1320, 1490-1526, 1681-1722, 1777 and 1818-1874 AD highlight the complex nature of glacier fluctuations during the Little Ice Age. The major intervals of expansioncorrespond to periods of reduced sunspot activity, suggesting that glacial activity may in part be forced by fluctuations in solar activity. A regional subalpine fir chronology was developed for the central Coast Mountains as proxy to reconstruct climate parameters to gain insights into mid- to late-LIA climates. Intervals of cooler summer air temperatures and above average snowpack correspond broadly with dominant periods of moraine building between 1610-1930 AD. These glacier histories corroborate research findings in other regions of Pacific North America and suggest the broad regional synchronicity reflects a glaciological response to one or more large scale climate forcings. Application of lichenometry in this research necessitated the construction of a Xanthoria elegans growth curve. An assessment of lichenometric measurements from the southern and central Coast Mountains provided the opportunity to construct X. elegans growth curve constrained by 19 control points. This regional curve is the first for this species in the Coast Mountains and provides a working framework for additional control points and revision.