Deglaciation of The Central St. Lawrence Lowland and The Champlain Sea
The Champlain Sea
Marine waters entered the central St. Lawrence Lowland after ice separating glacial Lake St Lawrence and marine waters east of the city of Quebec was breached. The water level in the lowland fell by a minimum of 18-37m (Pair and Rodrigues, 1993) and a maximum of approximately 60m (Parent and Occhietti, 1988) when marine waters entered the central St. Lawrence Lowland. The waters of glacial Lake St. Lawrence were replaced by marine waters, and in some parts of the lowland, the Laurentide Ice Sheet was in contact with marine waters, during the early stage of the marine transgression.
Invertebrate macrofossils (cirripeds, gastropods, plecypods and sponges) and (foraminifers and ostracodes) are common in the Champlain Sea Deposits. The invertebrate fossils indicate Arctic to sub-Arctic conditions in the Champlain Sea, except for the pelecypod Mya arenaria, which is related related to a low-water boreal phase of the Champlain Sea (Elson, 1969). The pelecypod is present in the uper part of Champlian Sea deposits and appear to be restricted to the area east of 75oW longitude.
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