Vaudreuil-Soulanges is part of the St Lawrence Valley. Two million years ago the region was subject to a series of glaciations that covered much of North America. The last in the series was the Wisconsin glaciation. The ice sheet weighed down the landscape. This created the depressions in the land that created the basins for Lake Saint-Louis, Lac des Deux-Montagnes and Lake Saint-Francis. As the ice sheet eroded, the region was mostly submerged 12000 years ago by an inland saltwater sea known as the Champlain sea. Once the glacier was melted, the land rose again, pushing the saltwater into the sea. 10000 years ago the body of water, now a fresh water lake, has been named by scholars as Lake Lampsilis.