Grain Size Distribution Patterns Supporting Sediment Bypassing on the Fraser River Delta Foreslope, British Columbia, Canada

Abstract

Sediment distribution patterns from sediment cores and grab samples on the Roberts Bank area of the Fraser River delta suggest that much of the coarsest sediment supplied to the mouth of the Fraser River bypasses the tidal flats and upper slope, and is deposited on the lower foreslope. Transport is via a number of subaqueous channels which serve not only as conduits for sediment bypassing, but also control the location and geometry of prodelta depositional lobes. Textural parameters, sedimentary structures and geometry of the deposits suggests that these lobes are formed by turbidity currents.