Distribution and depositional history of sediments in Baie des Chaleurs, Gulf of St. Lawrence

Modern sediment distribution in Baie des Chaleurs is controlled primarily by an interplay of water depth and wave climate. Modern sediment textures range from gravelly sand to silty clays. Much of the central part of the bay is covered by deposits of gravelly sand that are being reworked by wave turbulence and bottom currents. The present pattern of sedimentation started about 6000 years ago, and for about the past 5000 years, different sediment types have developed in various parts of the bay because of an interplay between tidal currents, wave-induced turbulence, and water depth. At present, this interplay is most intense in shallow nearshore environments, especially on the south side of the bay. Evidence cited elsewhere in the literature suggests that Atlantic waters may have flooded the Chaleur Trough as early as 14 000 years ago. This transgression gave way to a temporary regression about 8000 to 10 000 years ago because of a relatively rapid glacial rebound compared with the eustatic sea-level rise. A depositional pattern similar to that observed today probably occurred from 12 000 to 13 000 years B.P. but with more marine conditions than present, extending as far west as Dalhousie, New Brunswick.