CGRG Bibliography of Canadian Geomorphology
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Author : Bombin. E.R.
Date : 1982
Title : Holocene Paleolimnology of Mary Gregg Lake, Foothills of the Canadian Rocky Mountains, Canada,
Publication : Unpublished M.Sc. thesis. University of Alberta, Edmonton.
Issue :
Page(s) : 147 p
Abstract
Two cores from Mary Gregg Lake (o.o8 Sq. Km, 53 7'N, 117 28'W, and 1540 m a.s.l.) were submitted to a multi-variable analysis (stratigraphy, sedimentology, geochemistry, and micropaleontology), aiming at the reconstruction of its Holocene paleoecological evolution within the context of the surrounding area. Radiocarbon dates corrected for contamination suggest that the available record spans approximately the last 6000 years. During this period the watershed has been dominantly covered by boreal forest, although more open forest and mesic conditions are indicated before ca. 3500 BP. Many of the analyzed variables show a similar stratigraphic pattern, the sample data being structured in three basic clusters (zones). They suggest that: between ca. 6000±200 and3500±200 BP the lake was relatively more eutrophic and supported higher productivity; between 3500±200 and 1000±200 BP' the conditions were more oligotrophic, and the productivity was at its minimum; and after 1000±200 BP, the aquatic system returned to its predominantly mesotrophic state of today. It is suggested that the cause of these changes is a combination of environmental oscillations and geomorphic conditioning (the lake is located at the water divide of the valley, which limits its volume to a certain maximum). It is hypothesized that the predominance of a longer ice-free season could produce the effects observed before ca. 3500 BP; while a shorter ice-free season (colder?) and possibly wetter conditions could be related to the status between 3500±200 and 1000±200 BP. An intermediate situation seems to be dominant in the last 1000±200 years. Human impact has not been a major cause of change in this wilderness area, so far; however, future coal mining operations are scheduled for the vicinity of the lake.
Bibliography of Canadian Geomorphology