- Geol.the extensive region making up much of northern and central Canada underlain by Precambrian rocks that have been eroded to produce a low shieldlike profile.[1920-25]
* * *One of the world's largest geologic continental shields, centred on Hudson Bay and extending for 3 million sq mi (8 million sq km) over Canada from the Great Lakes to the Canadian Arctic and into Greenland, with small extensions into northern Minnesota, Wisconsin, Michigan, and New York.It is the largest mass of exposed Precambrian rock on earth. The region as a whole is composed of ancient crystalline rocks whose complex structure attests to a long history of uplift and depression, mountain building, and erosion.
* * *one of the world's largest geologic continental shields, centred on Hudson Bay and extending for 8,000,000 square km (3,000,000 square miles) over eastern, central, and northwestern Canada from the Great Lakes to the Canadian Arctic and into Greenland, with small extensions into northern Minnesota, Wisconsin, Michigan, and New York, U.S.The Canadian Shield constitutes the largest mass of exposed Precambrian (Precambrian time) rock on the face of the Earth. The region, as a whole, is composed of ancient crystalline rocks whose complex structure attests to a long history of uplift and depression, mountain building, and erosion. Some of the ancient mountain ranges can still be recognized as a ridge or belt of hills, but the present appearance of the physical landscape of the Canadian Shield is not so much a result of the folding and faulting and compression of the rocks millions of years ago as it is the work of ice in relatively recent geologic time. During the Pleistocene Epoch (1,600,000 to 10,000 years ago), the vast continental glaciers that covered northern North America had this region as a centre. The ice, in moving to the south, scraped the land bare of its overlying mantle of weathered rock. Some of this material was deposited on the shield when the ice melted, but the bulk of it was carried southward to be deposited south and southwest of the Canadian Shield.The resulting surface consists of rocky, ice-smoothed hills with an average relief of 30 m (100 feet), together with irregular basins, which are mostly filled by lakes or swamps. In places the old mountain ranges may be recognized by hills several hundreds of metres in height. The northeastern portion, however, became tilted up so that, in northern Labrador and Baffin Island, the land rises to more than 1,500 m (5,000 feet) above sea level.
* * *
Look at other dictionaries:
Canadian Shield — an area of about 2,000,000 sq mi (5,179,980 sq km) of Precambrian strata, consisting largely of granite, gneiss, marble, and other igneous and metamorphic rocks that occupy most of eastern and central Canada & part of NE U.S … English World dictionary
Canadian Shield — The Canadian Shield mdash; also called the Laurentian Plateau, or Bouclier Canadien (French) mdash; is a large geological shield covered by a thin layer of soil that forms the nucleus of the North American or Laurentia craton. It has a deep,… … Wikipedia
Canadian Shield — Kanadischer Schild Der Kanadische Schild (auch: Laurentischer Schild) ist der geologische Kern des nordamerikanischen Kontinents. Er umfasst die nördliche Hälfte des Halbkontinents und besteht aus Gesteinen, die zum Teil mehrere Milliarden Jahre… … Deutsch Wikipedia
Canadian Shield — Sp Kanãdos Skỹdas Ap Canadian Shield L regionas R Kanadoje ir ŠR JAV … Pasaulio vietovardžiai. Internetinė duomenų bazė
Canadian Shield — noun An area of very old bedrock surrounding Hudson Bay, and covering about half the land area of Canada. Syn: Laurentian Shield, Laurentian Plateau, Precambrian Shield … Wiktionary
Canadian Shield — /kæˌneɪdiən ˈʃild/ (say ka.naydeeuhn sheeld) noun a triangular area of Pre Cambrian rock in eastern Canada and the north eastern US. About 4 828 000 km2. Also, Laurentian Shield … Australian English dictionary
Canadian Shield — or Laurentian Plateau geographical name plateau region E Canada & NE United States extending from Mackenzie River basin E to Davis Strait & S to S Quebec, NE Minnesota, N Wisconsin, NW Michigan, & NE New York including the Adirondacks … New Collegiate Dictionary
Canadian Shield — noun a large plateau that occupies more than 40% of the land area of Canada; it extends from the Great Lakes northward to the Arctic Ocean • Syn: ↑Laurentian Plateau, ↑Laurentian Highlands • Instance Hypernyms: ↑tableland, ↑plateau • Part… … Useful english dictionary
Midwestern Canadian Shield forests — The Midwestern Canadian Shield forests ecoregion, in the Taiga and Boreal forests Biome, are of northern Canada. Contents 1 Setting 2 Flora 3 Fauna 4 Threats … Wikipedia
Canadian Forces — Canadian Armed Forces Forces armées canadiennes Emblem of the Canadian Forces Current form 1968 Service branches … Wikipedia