CGRG Bibliography of Canadian Geomorphology
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Author : Dowdeswell, J.A.
Date : 1985.
Title : Distribution and character of sediment in a tidewater glacier, southern Baffin Island, Canada
Publication : 14th Arctic Workshop : Arctic land-sea interaction, 6-8 November, 1985, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, Canada. - Bedford Institute of Oceanography, Dartmouth, Nova Scotia, Canada, 1985
Issue :
Page(s) : 227.
Abstract
The distribution, shape and grain size characteristics of sediments in a Baffin Island tidewater glacier are examined. At the glacier terminus a 0.8-2.9m thick zone of basal debris-rech (14-57 per cent by volume) ice underlies clean ice. Marginal ice flow is extending, and high level debris-rech bands are largely absent. Little supra-glacial sediment is present except as isolated rock-falls. Measured sediment characteristics were: 1. Clast roundness, 2. Fourier shape of quartz sand grains, 3. Grain size distribution. Modal shapes of basal ice and rock form clasts were sub-rounded and angular respectively. Fourier analysis showed quartz sand grains from clean ice and rock-fall were more angular and micro-textured than those from basal ice. Grain size envelopes for debris in basal ice, melt water streams, and near shore environments are described and are compared with those from fiord glacio marine sediment. The distribution of sediment within the tide-water glacier controls which mechanism's of debris release are important. This in turn influences the depositional facies found. Sediment is released mainly by: 1. Direct melting and 2. Sub glacial streams and associated density overflows. Calving is relatively unimportant. Acoustic sounding revealed three morainal banks offshore of the glacier terminus, probably relating to melt-out of basal debris. A calculated rate of basal sediment supply by melting of 6.1**-10 cu m/M/A is similar to that required to build such banks.
Bibliography of Canadian Geomorphology