The largest craton in the world, a significant geographical feature of central and eastern Canada, and the northeastern United States. It forms an immense rocky ring centered around Hudson's Bay. 4.4 million square kilometers in size, it covers almost half of Canada's landmass: most of Quebec, Nunavut, and Ontario, half of Manitoba, parts of Saskatchewan and Alberta, and a good part of the Northwest Territories.
It is also known as the Precambrian Shield and the Laurentian Shield or Laurentian Plateau.
It is the earth’s greatest area of exposed Precambrian rock, representing the first part of the eventual North American continent to rise above sea level. Once mountainous, time and erosion helped to flatten it, a job completed during the Pleistocene Ice age when glaciation planed the region. Hudson's Bay itself is a dimple in the shield formed by the weight of the glaciers, which is slowly rebounding.
The region is rich in forests and minerals, and once boasted a healthy
fur trade. As a result of glacial action, the soil is thin and the drainage poor, making the region unattractive for farming.
Access to the mineral rich shield resulted in numerous mining sites, most famously the Sudbury Ontario nickel mines. The mine in turn provided the ideal site for a neutrino observatory, the Sudbury Neutrino Observatory.