Fjord-mouth submarine moraines, SW Newfoundland

Abstract

Arcuate submarine moraines at the mouths of fjords along the SW coast of Newfoundland are interfingered with glacimarine deposits. Based on radiocarbon dates from piston cores, it has been proposed that they formed when Late Wisconsinan glacier ice on the continental shelf of Atlantic Canada calved back into deep water, isolating the Newfoundland Ice Cap (NIC) c. 14 ka BP. In SW Newfoundland, drawdown from the interior of the ice cap was localized in fjords and ice margins were stabilized at fjord mouths. Similar submarine moraines are found off the west coast of Newfoundland, but do not occur at fjord mouths elsewhere. The coast of Newfoundland is indented by a series of very narrow fjords (average width 1 km) that are relatively shallow (average maximum depth 250 m) compared with those of the NE coast (cf. Shaw et al. 2000) (Fig. 1). The exception is Bay d'Espoir, the deepest fjord in Newfoundland, which attains a maximum depth of 790 m (Fig. 1c). The fjord entrances coincide with the boundary between crystalline basement rocks that predominate onshore and the younger Palaeozoic sedimentary rocks offshore (Fader et al. 1989). Fig. 1. ( a ) Submarine moraines off Bay de Loup and White Bear Bay. Acquisition …