The purpose of this research is to gain understanding of the occurrence and origin of streamlined forms in central British Columbia. More than 50,000 landforms, primarily drumlins and crag-and-tail ridges, were digitally mapped over an area covering five 1:250,000 NTS map sheets. Visual Basic programs were written to statistically analyze the streamlined forms database and to simulate site-scale, two-dimensional glacial erosion. Results show three principal ice and/or meltwater flow directions: southeast flows probably originating in the Skeena Mountains, northeast flows from the Coast Mountains and Quanchas Range, and west flows originating east of the Babine and Telkwa Ranges. Rat-tails and striae occur up to 1680 m elevation and record uphill flow to the west in these ranges.
Streamlined forms were investigated at outcrop scale (e.g. rat-tails), landform scale (e.g. drumlins) and landscape scale (as defined by closed contours). On bedrock outcrops, cross-cutting striae are common and they both parallel and cross-cut rat-tails. Small rat-tails occur on, and parallel to, larger rat-tails but they do not cross-cut, suggesting a different origin than striae. Rat-tails are interpreted as being formed by subglacial meltwater flows, an interpretation supported by the glacial erosion model. Lowland streamlined forms (e.g. drumlins and crag-and-tails) are interpreted as either glacially-formed ridges subsequently shaped by meltwater floods or as being formed entirely by meltwater floods. This interpretation is largely based on the common occurrence of interconnecting hairpin furrows around these streamlined forms and on the demonstrated association of hairpin furrows with fluvial erosion.
The results of topographic analysis indicate that an interconnecting system of valleys separates uplands that can be objectively defined by single (closed) contours. The aspect ratios of the uplands are highly correlated (L/W = 2.38, R2 = 0.89) with values that are similar to those reported for braid bars and erosional residuals thought to have been formed by glacial outburst floods. This upland/lowland landform assemblage may, in places, represent streamlined erosional residuals within braided channel networks formed, at least in part, by subglacial or glacial outburst floods.
| Identifer | oai:union.ndltd.org:uvic.ca/oai:dspace.library.uvic.ca:1828/2691 |
| Date | 03 May 2010 |
| Creators | McClenagan, Jerry Donald |
| Contributors | Levson, Victor M., Van der Flier-Keller, Eileen |
| Source Sets | University of Victoria |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Rights | Available to the World Wide Web |
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