What is the Canadian Shield?

The Canadian Shield is a vast region of ancient Precambrian rock covering about 8 million square kilometres, roughly half of Canada's 9.985 million square kilometre land area. The Shield curves in a horseshoe shape from Labrador through northern Quebec, Ontario, Manitoba, Saskatchewan, the Northwest Territories, and Nunavut, around Hudson Bay and James Bay. It is one of the largest and geologically oldest terrains on Earth, with exposed bedrock up to 4.28 billion years old (the Acasta Gneiss in the Northwest Territories).

The Shield is a craton, a stable continental core that was already ancient when most of the present continents formed. It consists of Precambrian igneous and metamorphic rock that has been worn down by erosion over hundreds of millions of years to a low rolling plateau, with elevations generally below 600 metres. Pleistocene glaciations (the most recent ending about 12,000 years ago) scoured the surface, leaving exposed rock, countless lakes (Canadian Shield lakes account for about 60 per cent of the world's freshwater lakes by count), muskeg, and characteristic glacial landforms including drumlins, eskers, and moraines.

The Shield is one of Canada's most economically productive regions. The Sudbury Basin (formed by a 1.85-billion-year-old meteorite impact) is a major source of nickel, copper, platinum, palladium, and gold for Vale, Glencore, and KGHM operations. Northern Saskatchewan's Athabasca Basin holds the richest uranium deposits on Earth, with Cameco operating the McArthur River and Cigar Lake mines. Diamond mines at Ekati, Diavik, and Gahcho Kue in the Northwest Territories have produced billions of dollars of gem-quality stones since 1998. Iron ore is mined at the Labrador Trough on the Quebec-Labrador border. Gold mines at Red Lake, Timmins, Kirkland Lake, Detour Lake, and Val-d'Or have produced more than 200 million ounces since the early 1900s.

The Shield's rivers and lakes generate hydroelectric power that supplies much of the electricity used in Quebec, Manitoba, Ontario, and Newfoundland and Labrador. Hydro-Quebec's La Grande complex and Robert-Bourassa generating station in James Bay, Nalcor's Churchill Falls station in Labrador (5,428 megawatts), and Manitoba Hydro's Nelson River system together produce more renewable energy than any comparable region in North America. Indigenous nations including the Cree, Innu, Anishinaabe, and Dene have lived in the Shield for millennia. Modern resource agreements such as the James Bay and Northern Quebec Agreement of 1975, the 2002 Paix des Braves between Quebec and the Cree Nation, and the 1993 Nunavut Land Claims Agreement transfer royalties, decision-making, and economic benefits to Indigenous governments.