Canadian Shield

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Canadian Shield

or

Laurentian Plateau

(lôrĕn`chən), U-shaped region of ancient rock, the nucleus of North America, stretching N from the Great Lakes to the Arctic Ocean. Covering more than half of Canada, it also includes most of Greenland and extends into the United States as the Adirondack Mts. and the Superior Highlands. The first part of North America to be permanently elevated above sea level, it has remained almost wholly untouched by successive encroachments of the sea upon the continent. It is the earth's greatest area of exposed Archaean-age rock; the metamorphic rocks of which it is largely composed were probably formed in the Precambrian. Repeatedly uplifted and eroded, it is today an area of low relief (c.1,000–2,000 ft/305–610 m above sea level) with a few monadnocks and low mountain ranges (including the Torngat and Laurentian Mts.) probably eroded from the plateau during the Cenozoic era. During the Pleistocene epoch, continental ice sheets depressed the land surface (see Hudson BayHudson Bay,
inland sea of North America, c.475,000 sq mi (1,230,000 sq km), c.850 mi (1,370 km) long and c.650 mi (1,050 km) wide, E central Canada. Hudson Bay and James Bay (its southern extension) and all their islands border Nunavut Territory, Manitoba, Ontario, and Quebec.
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), scooped out thousands of lake basins, and carried away much of the region's soil. Drainage is generally very poor on the shield. The southern part of the shield has thick forests while the north is covered with tundra. The region is largely undeveloped but has great water-power potential and is a source of minerals, timber, and fur-bearing animals.

Canadian Shield

[kə′nād·ē·ən ′shēld]
(geology)

Canadian Shield

(in Canada) the wide area of Precambrian rock extending west from the Labrador coast to the basin of the Mackenzie and north from the Great Lakes to Hudson Bay and the Arctic: rich in minerals