SURFICIAL GEOLOGY OF THE NORTHWESTERN CANADIAN CONTINENTAL-SHELF

The northwestern Canadian continental shelf, including Dixon Entrance, Hecate Strait and Queen Charlotte Sound, can be divided into four surficial geological units all overlying Tertiary bedrock within the Queen Charlotte Basin. They include: (1) glacial till, deposited primarily in the troughs between banks and considered to be late Wisconsinan in age; (2) giaciomarine mud, deposited in the troughs as ice retreated from the shelf; (3) Queen Charlotte sands and gravels, outwash deposition in the north and sublittoral sand deposition in the south during sea level low stand and subsequent reworking during transgression; and (4) Queen Charlotte muds, deposited within the troughs of the region from late Wisconsinan times until present. These units are a result of a glaciation ending 15,000-13,000 years BP followed by relative sea level lowering by approximately 100 m, that persisted until 10,500 years ago, and a subsequent transgression that occurred over approximately 1500 years in a series of steps .