The intent of the research described in this thesis was to reconstruct and document Holocene glacier activity in the central British Columbia Coast Mountains. Despite ongoing efforts to describe glacier fluctuations in the southern and northern Coast Mountains, only limited attention has been directed to revealing the Holocene histories of glaciers in the central Coast Mountain region. The goals of this research were twofold: firstly, to describe mid-Holocene glacier advances at five remote glacier sites in the central Coast Mountains, and secondly, to detail Little Ice Age (LIA) glacier fluctuations at four glacier sites in the central Coast Mountains.
The mid-Holocene behaviour of Canoe, Fyles, Jacobsen, Tchaikazan and Icemaker glaciers was investigated using dendroglaciological techniques and stratigraphic analysis. Subfossil wood evidence suggests these glaciers were expanding into standing forests prior to 6.63, 4.90 and 4.20 ka. Stratigraphically constrained woody detritus at Fyles Glacier records the progradational history of a Gilbert-type delta forming in response to glacial expansion between 7.02-5.47 ka. Glacial expansion occurring between 7.50-4.00 ka has regional correlatives, suggesting coherent broad-scale climate forcing mechanisms influenced glacial mass balance at this time.
Insight into the LIA behaviour of central Coast Mountain glaciers was provided by conducting lichenometric surveys of Rhizocarpon spp. across LIA moraines at Pattullo, Fyles, Deer Lake and Jacobsen glaciers. The presence of a second, lesser known, lichen species at some sites 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 build a X. elegans growth curve constrained by 18 control points. Lichenometric surveys revealed dominant moraine building episodes at 890-1020, 1280-1320, 1490-1530, 1680-1720, 1780 and 1820-1870 AD, highlighting the complex nature of glacier fluctuations during the LIA.
A regional subalpine fir tree-ring chronology (1610-2010 AD) was developed from four stands located in the central Coast Mountains for dendroclimatological investigations. Correlation analyses show that the radial growth of trees corresponded to variations in the mean June/July air temperature and May 1st snowpack. This relationship was used to reconstruct these climate parameters for the duration of the tree-ring record. Intervals of cooler summer air temperatures and above average snowpack were found to broadly correspond with dominant periods of LIA moraine building from 1610-1930 AD.
This reconstruction of mid-Holocene and LIA glacial history offered insights consistent with the emerging record of glacial activity described for the southern Coast Mountain glaciers. It also provides the first evidence for mid-Holocene glacial expansion in the central and northern Coast Mountains. The application of lichenometry in the central Coast Mountains documents the regional LIA behaviour of glaciers and the construction of a Xanthoria elegans growth curve for the Coast Mountains provides a framework for future geobotanical dating using this species. / Graduate
| Identifer | oai:union.ndltd.org:uvic.ca/oai:dspace.library.uvic.ca:1828/3473 |
| Date | 18 August 2011 |
| Creators | Harvey, Jillian Elizabeth |
| Contributors | Smith, Daniel J. |
| Source Sets | University of Victoria |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Rights | Available to the World Wide Web |
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