CGRG Bibliography of Canadian Geomorphology
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Author : Dalrymple, R.W.
Date : 1973
Title : Preliminary investigations of an intertidal sand body, Cobequid Bay, Bay of Fundy
Publication : Maritime Sediments
Issue : 9(1):
Page(s) : 21-28
Abstract
The highest recorded tidal range in the world, 55 ft., was measured off burntcoat head in Cobequid Bay, Nova Scotia, Canada. At low tide, an extensive complex of sand bars is exposed. At high tide, these sand bodies are covered by several tens of feet of water. Thus, the results of processes operating at depths otherwise virtually inaccessible are easily available for study, modified by those features attributable to emergence. Selmah Bar appears to be in dynamic equilibrium. Megaripple slip face orientations yield a strongly bimodal distribution. Thus, depending on the preservation of cross-stratification, cross-bedding might be expected to exhibit the same bimodal distribution with the maxima 180 deg apart. Tidal current time-velocity asymmetry is a pervasive factor in the study of intertidal or tidal environments and determines the dominant direction of sediment transport. The pattern of sediment transport due to tidal currents is disrupted to a considerable extent by open-channel flow immediately before and during exposure, resulting in a complex transport system. The plan form of megaripples results from a complex interplay of current velocity, bedload, water depth, length of time for development and the uniformity of current direction. Megaripple amplitude and wavelength are strongly influenced by currentvelocity and water depth, and possibly by grain size.
Bibliography of Canadian Geomorphology