Proglacial Lakes

It is believed that the north and south areas of the Champlain Sea each possessed a slightly different history.  In the southern regions of the Champlain Sea basin, evidence such as the presence of the freshwater ostracode, Candona subtriangulata, within the sediments indicates the presence of proglacial lakes prior to the entry of saline water.  However in more northern regions,  there is no evidence of such a freshwater episode.  The map below (modified after Harington) shows the hypothesized boundary between the two regions of differing histories.

In the next few pages, the lithology of three different areas within the Champlain Sea basin will be presented.  The first region, Lake Champlain in Vermont, is an example of an area that hosted a proglacial lake, whereas the second region, St-Dominique (located approximately 50 km east of Montreal) did not.  Finally the lithology of an area close to Ottawa will be presented.

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