The Canadian Shield is a large craton in eastern and central Canada and adjacent portions of the United States, composed of bare rock dating to the Precambrian Era (between 4.5 billion and 540 million years ago). It is also called the Precambrian Shield, Laurentian Shield, or Laurentian Plateau.
Canadian Shield - Regional extent.
Other than the Greenland section, the Shield is approximately circular, with Hudson Bay in the middle. It covers much of Greenland; Labrador; most of Q ...
Other than the Greenland section, the Shield is approximately circular, with Hudson Bay in the middle. It covers much of Greenland; Labrador; most of Quebec north of the St. Lawrence River; much of Ontario outside the southern peninsula between the Great Lakes; the Adirondack Mountains of northern New York; parts of Michigan, Wisconsin, and Minnesota; the central portion of Manitoba away from Hudson Bay and the Great Plains; northern Saskatchewan; a small portion of north-eastern Alberta; and the mainland northern Canadian territories to the ...
Such a large area of exposed, old rock requires some explanation. The current surface expression of the Shield is one of very thin soil lying on top of the bedrock, with many bare outcrops. This arrangement was caused by severe glaciation during the last ice age, which covered the Shield and scraped the rock clean. The multitude of rivers and lakes in the entire region is caused by the watersheds of the area being so young and in a state of sorting themselves out with the added effect of post-glacial rebound. The Shield was originally an are ...
