Great Lakes–St. Lawrence Lowlands

The Great Lakes-St. Lawrence Lowlands, or simply St. Lawrence Lowlands, is a physiographic region of Eastern Canada that comprises a section of southern Ontario bounded on the north by the Canadian Shield and by three of the Great Lakes — Lake Huron, Lake Erie and Lake Ontario — and extends along the St. Lawrence River to the Strait of Belle Isle and the Atlantic Ocean. The lowlands comprise three sub-regions that were created by intrusions from adjacent physiographic regions — the West Lowland, Central Lowland and East Lowland. The West Lowland includes the Niagara Escarpment, extending from the Niagara River to the Bruce Peninsula and Manitoulin Island. The Central Lowland stretches between the Ottawa River and the St. Lawrence River. The East Lowland includes Anticosti Island, Îles de Mingan, and extends to the Strait of Belle Isle.

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 Lowlands is in the traditional territories of the Mohawk, the Algonquian and Iroquoian peoples, and the Cree.

The St. Lawrence Lowlands was covered by surficial deposits left by ice sheets following the Pleistocene glaciations. It is the smallest of Canada's seven physiographic regions — the others being the Arctic Lands, the Cordillera, the Interior Plains, the Canadian Shield, the Hudson Bay Lowlands and the Appalachian Uplands — distinguished by topography and geology. The boundaries of the area largely reflect that of the Mixedwood Plains Ecozone, the smallest of Canada's fifteen terrestrial ecozones.