Abstract

Sand winnowed from bay-floor deposits and eroded from sea cliffs in the Minas Basin has been swept into a series of intertidal sand-body complexes. Continuous seismic profiles show that these are plano-convex or tabular sand masses up to 30 m thick and 30 km long. Two types of complex are present: the Windsor Bay complex is a tidal delta type, while the Cobequid Bay complex represents a braided type. The Windsor Bay complex consists of a main channel, flanked by two levee-like lateral bars, capped by a lunate cross-bar. The complex is localized by the phase difference between the retarded estuary tide and the tide of the main bay. The Cobequid Bay complex consists of rhomboid to oval bars, whose blunt ends face the incoming tide, which are defined by interlacing channels.Tidal current velocity data measured over the complex indicate two regimes: a high-water, sheet-flood phase and a low-water, channel phase. On the surface of the bars, first-order sandwaves show mainly flood asymmetry while second-order sandwaves show mainly ebb asymmetry. The flood asymmetry of the bars and larger sandwaves is a consequence of the skewed nature of the tidal cycle. Sand transport in the Minas Basin appears to be eastward, along both shores.

You do not currently have access to this article.