CGRG Bibliography of Canadian Geomorphology
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Author : Fleming, E.M.; and Walker, I.R.
Date : 2007.
Title : Reconstruction of Holocene environmental changes in northern British Columbia using fossil midges.
Publication : Annual Meeting, Western Division of the Canadian Association of Geographers, March 8-10, 2007. University College of the Fraser Valley, Abbotsford, British Columbia.
Issue : Program and Abstract Volume.
Page(s) : 25.
Abstract
Lake sediments contain the remains of midge communities that may be used as biological proxies for inferring past environmental changes. Freshwater midges, including Chironomidae, Chaoboridae and Ceratopogonidae, from two alpine tarns (Pyramid Lake and Bullwinkle Lake) in the Cassiar Mountains of northern British Columbia are being used to estimate Holocene palaeotemperature changes, and more specifically, to test for the presence of the Milankovitch thermal maximum (an early Holocene warm interval coinciding with peak Holocene summer solar insolation). Mean July air temperatures will be reconstructed using midge inference models developed via weighted averaging-partial least squares (WAPLS) regression. Preliminary results from Pyramid Lake indicate the absence of midge assemblages prior to 9500 14C yr BP (shortly after the area was deglaciated). Micropsectra trofasciata/radialis, Sergentia, Heterotrissocladius marcidus and Abiskomyia are abundant in the core, suggesting that cold-water conditions have prevailed at this site, at least through the mid-to-late Holocene (ca. 4000 to 1500 14C yr BP). The palaeoclimatic record for northern British Columbia is filled with inconsistencies. This study will attempt to resolve some of the discrepancies in the timing of climate change in the continental interior.
Bibliography of Canadian Geomorphology