From 13,000 to 10,000 years ago the St. Lawrence Lowland rose rapidly (as much as 20 m per century) in response to the disappearance of the ice mass. The highest relict strand lines of the Champlain Sea are now 230 m above sea level on the north side of the lowlands and 75 m lower on the south side.

The St. Lawrence Lowlands is one of the most densely populated, prosperous and productive regions in Canada. Major urban areas include Toronto, Montreal, Ottawa-Gatineau and Quebec City. The St. Lawrence Lowlands was covered by surficial deposits left by ice sheets following the Pleistocene glaciations. [1]

The Great Lakes St. Lawrence Lowlands were the traditional lands of the Mohawk the most easterly tribe of the Iroquoian-speaking Haudenosaunee Confederacy, the Algonquian and Iroquoian peoples, and the one of the largest groups of First Nations in North America.

The St. Lawrence Lowlands were formed almost 500 million years ago. There was an ice age and when the ice age was over all the glaciers started melting. This is called glaciation.

The Great Lakes–St. Lawrence region comprises the peninsula of southern Ontario bounded by the Canadian Shield and Lakes Huron, Erie, and Ontario. It extends along the St. Lawrence River to the Atlantic Ocean.