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Tidal currents on the sandy, southern slope of Fraser River delta have generated dunes with heights of 0.5–3.5 m and lengths of 11–108 m. Dune geometry and migration measurements indicate net sediment transport to the northwest in the direction of flood tidal currents. Two current meters moored in the dune field showed greater frequencies of occurrence and higher mean current speeds in the flood direction compared with the ebb. Predictions from two bed-material load models indicate sediment transport is overwhelmingly dominated by flood currents. There is no obvious source of sand to replace sediment transported in the dune field, suggesting net erosion of the surface. A previous analysis of bathymetric data also shows recent erosion of the lower slope and overall slope steepening. These patterns of erosion could lead to slope failure and damage to coastal structures.

Four surficial geological units are defined geophysically for Hecate Strait on the northern British Columbia continental shelf. They consist of Tertiary bedrock (unit 1) unconformably overlain in much of the strait of glacial till (unit 2), which is in turn overlain below 200 m water depth by thick silts (unit 4) and above 200 m by Quaternary sands and gravels (unit 3), except in areas where till or Tertiary bedrock is at or near surface.Glacial ice covered most of the strait at some time in the Pleistocene, but evidence for a Late Wisconsinan advance is more prevalent in the principal troughs of the strait. Sea level was as low as the present-day 180 m isobath during the late Tertiary or early Quaternary and possibly as low as 100 m at the end of the Pleistocene, based on the presence of drainage channels, wave-cut terraces, and both shore-oblique and shore-parallel sand ridges. Sedimentary bedforms found ubiquitously above 100 m appear to be in equilibrium with the present hydrodynamic conditions, and their presence suggests that significant seabed erosion and transport occur within the strait.

Sedimentological and geophysical studies of the surficial geology of the Labrador Shelf reveal evidence of sediment provenance and modern seabed dynamics. Analyses of lithic fragments of grab samples from southern Saglek Bank and Makkovik Bank indicate that a high proportion of the surficial cover is of ice-rafted origin. Fossilferous carbonate fragments of Paleozoic age suggest a northern Greenland or Arctic island provenance. Heavy-mineral analyses reveal minerals common to igneous and high-grade metamorphic rocks. The Precambrian terrains of Labrador are a possible early sediment source, although similar more northerly terrains could be more recent sources.The geologic environments of Saglek and Makkovik banks differ, as shown by sediment textures and the distribution and form of ice scours that are abundant over the Labrador Shelf. The contrasting environments result largely from differing degrees of postglacial sediment reworking, evidenced by mineral hydraulic equivalence of the sand fractions from both banks. Sediments on the Makkovik Bank undergo present-day transport as a result of a strong hydrodynamic regime. The deeper, broader Saglek Bank is a hydrodynamically quiet zone except near the seaward bank margin, where strong sediment reworking by currents has and is presently taking place.