CGRG Bibliography of Canadian Geomorphology
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Author : Cant, D.J.; and Walker, R.G.
Date : 1978
Title : Fluvial processes and facies sequences in the sandy braided South Saskatchewan River, Canada
Publication : Sedimentology
Issue : 25(5):
Page(s) : 625-648
Abstract
The South Saskatchewan River has a long-term average discharge of 275 cu m/sec, with flood peaks in the range of 1500 to 3800 cu m/sec. South of Saskatoon, the four major types of geomorphological elements recognized are channels, slipface-bounded bars, sand flats and vegetated islands, and floodplains. Major channels are 3-5 m deep, up to 200 m wide, and flow around sand flats which are 50-2000 m long, and around vegetated islands up to 1 km long. At areas of flow expansion, long, straight-crested, cross-channel bars form. During falling stage, a small part of the crest of the cross-channel bar may become emergent and act as a nucleus for downstream and lateral growth of a new sand flat. The dominant channel bedforms are dunes, which deposit trough cross bedding. Cross-channel bars deposit large sets of planar tabular cross bedding. Sand flats that grow from a nucleus on a cross-channel bar are composed mostly of smaller planar tabular sets, with some parallel lamination, trough cross-bedding, and ripple cross-lamination. A typical facies sequence related to sand flat growth consists of in-channel trough cross-bedding, overlain by a large (1-2 m) planar tabular set (cross-channel bar), overlain in turn by a complex association mostly of small planar tabular cross-beds, trough cross-beds and ripple cross-lamination. By contrast, a second stratigraphic sequence can be proposed, related only to channel aggradation. It would consist dominantly of trough cross-beds, decreasing in scale upward, and possibly interrupted by isolated sets of planar tabular cross-bedding if a cross-channel bar formed, but failed to grow into a sand flat. During final filling of the channel, ripple cross-lamination and thin clay layers may be deposited. In the South Saskatchewan, these sequences are a minimum of 5 m thick, and are overlain by 0.5-1 m of silty and muddy vertical accretion deposits
Bibliography of Canadian Geomorphology