The Canadian Shield, also called the Laurentian Plateau, or Bouclier canadien (French), is a large area of exposed Precambrian igneous and high-grade metamorphic rocks (geological shield) that forms the ancient geological core of the North American continent (the North American Craton or Laurentia). Composed of igneous rock resulting from its long volcanic history, the area is covered by a thin layer of soil. With a deep, common, joined bedrock region in eastern and central Canada, it stretches north from the Great Lakes to the Arctic Ocean, covering over half of Canada; it also extends south into the northern reaches of the United States. Human population is sparse, and industrial development is minimal, while mining is prevalent.
Stratigraphic range: Precambrian
|Unit of||North American craton|
|Area||8 000 000 km2|
The Canadian Shield is a broad region of Precambrian rock (pictured in shades of red) that encircles Hudson Bay. It spans eastern, northeastern, and east-central Canada and the upper midwestern United States.
The Canadian Shield is a physiographic division, consisting of five smaller physiographic provinces: the Laurentian Upland, Kazan Region, Davis, Hudson and James. The shield extends into the United States as the Adirondack Mountains (connected by the Frontenac Axis) and the Superior Upland. The Canadian Shield is U-shaped and is a subsection of the Laurentia craton signifying the area of greatest glacial impact (scraping down to bare rock) creating the thin soils. The Canadian Shield is more than 3.96 billion years old. The Canadian Shield once had jagged peaks, higher than any of today's mountains, but millions of years of erosion have changed these mountains to rolling hills.
The Canadian Shield is a collage of Archean plates and accreted juvenile arc terranes and sedimentary basins of the Proterozoic Eon that were progressively amalgamated during the interval 2.45 to 1.24 Ga, with the most substantial growth period occurring during the Trans-Hudson orogeny, between ca. 1.90 to 1.80 Ga. The Canadian Shield was the first part of North America to be permanently elevated above sea level and has remained almost wholly untouched by successive encroachments of the sea upon the continent. It is the Earth's greatest area of exposed Archean rock. The metamorphic base rocks are mostly from the Precambrian (between 4.5 billion and 540 million years ago) and have been repeatedly uplifted and eroded. Today it consists largely of an area of low relief 300 to 610 m (980 to 2,000 ft) above sea level with a few monadnocks and low mountain ranges (including the Torngat and Laurentian Mountains) probably eroded from the plateau during the Cenozoic Era. During the Pleistocene Epoch, continental ice sheets depressed the land surface creating Hudson Bay, scooped out thousands of lake basins, and carried away much of the region's soil.
When the Greenland section is included, the Shield is approximately circular, bounded on the northeast by the northeast edge of Greenland, with Hudson Bay in the middle. It covers much of Greenland, Labrador, most of Quebec north of the St. Lawrence River, much of Ontario including northern sections of the Ontario Peninsula, the Adirondack Mountains of New York, the northernmost part of Lower Michigan and all of Upper Michigan, northern Wisconsin, northeastern Minnesota, the central/northern portions of Manitoba away from Hudson Bay, northern Saskatchewan, a small portion of northeastern Alberta, and the mainland northern Canadian territories to the east of a line extended north from the Saskatchewan/Alberta border (Northwest Territories and Nunavut). In total, the exposed area of the Shield covers approximately 8,000,000 km2 (3,100,000 sq mi). The true extent of the Shield is greater still and stretches from the Western Cordillera in the west to the Appalachians in the east and as far south as Texas, but these regions are overlaid with much younger rocks and sediment.
The Canadian Shield is among the oldest on earth, with regions dating from 2.5 to 4.2 billion years. 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 area of very large, very tall mountains (about 12,000 metres or 39,000 feet) with much volcanic activity, but over hundreds of millions of years, the area has been eroded to its current topographic appearance of relatively low relief. It has some of the oldest (extinct) volcanoes on the planet. It has over 150 volcanic belts (now deformed and eroded down to nearly flat plains) whose bedrock ranges from 600 to 1200 million years old.
Each belt probably grew by the coalescence of accumulations erupted from numerous vents, making the tally of volcanoes reach the hundreds. Many of Canada's major ore deposits are associated with Precambrian volcanoes.
The Sturgeon Lake Caldera in Kenora District, Ontario, is one of the world's best preserved mineralized Neoarchean caldera complexes, which is 2.7 billion years old. The Canadian Shield also contains the Mackenzie dike swarm, which is the largest dike swarm known on Earth.
Mountains have deep roots and float on the denser mantle much like an iceberg at sea. As mountains erode, their roots rise and are eroded in turn. The rocks that now form the surface of the Shield were once far below the Earth's surface.
The high pressures and temperatures at those depths provided ideal conditions for mineralization. Although these mountains are now heavily eroded, many large mountains still exist in Canada's far north called the Arctic Cordillera. This is a vast deeply dissected mountain range, stretching from northernmost Ellesmere Island to the northernmost tip of Labrador. The range's highest peak is Nunavut's Barbeau Peak at 2,616 metres (8,583 ft) above sea level. Precambrian rock is the major component of the bedrock.
The North American craton is the bedrock forming the heart of the North American continent and the Canadian Shield is the largest exposed part of the craton's bedrock.
The Canadian Shield is part of an ancient continent called Arctica, which was formed about 2.5 billion years ago during the Neoarchean era. It was split into Greenland, Laurentia, Scotland, and Siberia, and is now roughly situated in the Arctic around the current North Pole.
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 ice age, which covered the Shield and scraped the rock clean.
The lowlands of the Canadian Shield have a very dense soil that is not suitable for forestation; it also contains many marshes and bogs (muskegs). The rest of the region has coarse soil that does not retain moisture well and is frozen with permafrost throughout the year. Forests are not as dense in the north.
The Shield is covered in parts by vast boreal forests in the south that support natural ecosystems as well as a major logging industry. This boreal forest area includes ecoregions such as the Eastern Canadian Shield taiga that covers northern Quebec and most of Labrador, and the Midwestern Canadian Shield forests that run westwards from Northwestern Ontario. Hydrographical drainage is generally poor, the soil compacting effects of glaciation being one of the many causes. Tundra typically prevails in the northern regions. Many mammals such as caribou, white-tailed deer, moose, wolves, wolverines, weasels, mink, otters, grizzly bear, polar bears and black bears are present. In the case of polar bears (Ursus maritimus) the Shield area contains many of the denning locations such as the Wapusk National Park.
The Canadian Shield is one of the world's richest areas in terms of mineral ores. It is filled with substantial deposits of nickel, gold, silver, and copper. Throughout the Shield there are many mining towns extracting these minerals. The largest, and one of the best known, is Sudbury, Ontario. Sudbury is an exception to the normal process of forming minerals in the Shield since the Sudbury Basin is an ancient meteorite impact crater. Ejecta from the meteorite impact was found in the Rove Formation in May 2007. The nearby but less known Temagami Magnetic Anomaly has striking similarities to the Sudbury Basin. This suggests it could be a second metal-rich impact crater.
In northeastern Quebec, the giant Manicouagan Reservoir is the site of an extensive hydroelectric project (Manic-cinq, or Manic-5). This is one of the largest-known meteorite impact craters on Earth.
The Flin Flon greenstone belt in central Manitoba and east-central Saskatchewan is one of the largest Paleoproterozoic volcanic-hosted massive sulfide (VMS) districts in the world, containing 27 copper-zinc-(gold) deposits from which more than 183 million tons of sulfide have been mined.
The Shield, particularly the portion in the Northwest Territories, has recently been the site of several major diamond discoveries. The kimberlite pipes in which the diamonds are found are closely associated with cratons, which provide the deep lithospheric mantle required to stabilize diamond as a mineral. The kimberlite eruptions then bring the diamonds from over 150 kilometres (93 mi) depth to the surface. The Ekati and Diavik mines are actively mining kimberlite diamonds.
The André-Michaux Ecological Reserve, or Réserve écologique André-Michaux, is an ecological reserve in Quebec, Canada. It protects a variety of vegetation types typically of the Canadian Shield.Athabasca Basin
This article is about the uranium mining region near Lake Athabasca. Not to be confused with the drainage basin of the Athabasca River.
The Athabasca Basin is a region in the Canadian Shield of northern Saskatchewan and Alberta Canada. It is best known as the world's leading source of high-grade uranium and currently supplies about 20% of the world's uranium.The basin is located just to the south of Lake Athabasca, west of Wollaston Lake and encloses almost all of Cree Lake. It covers about 100,000 square kilometres in Saskatchewan and a small portion of Alberta. The surface of the basin consists of main sandstone sediment varying from 100 to 1000 metres in depth. The uranium ore is mostly found at the base of this sandstone, at the point where it meets the basement.
On the northern and eastern edges are the communities of Fort Chipewyan in Alberta and Camsell Portage, Stony Rapids, Fond du Lac, Black Lake and Wollaston Lake in Saskatchewan. Much of the Athabasca Basin is within the migratory range of the Beverly caribou herd a major source of sustenance for the Denesuline communities.
Within the basin are the Athabasca Sand Dunes Provincial Park on the south shore of Lake Athabasca and the Carswell crater. The Cluff Lake mine site is located in the crater area.
Points North Landing a permanent supply depot and camp serves the eastern area of the basin.
Road access to the area is provided by Saskatchewan Highway 955 from the village of La Loche on the west side and Saskatchewan Highway 914 and Saskatchewan Highway 905 north of the town of La Ronge on the east side.Carswell crater
Carswell is an impact crater within the Athabasca Basin of the Canadian Shield in northern Saskatchewan, Canada. It is 39 kilometres (24 mi) in diameter and the age is estimated to be 115 ± 10 million years (Lower Cretaceous). The crater is exposed at the surface.Central Ontario
Central Ontario is a secondary region of Southern Ontario in the Canadian province of Ontario that lies between Georgian Bay and the eastern end of Lake Ontario.
The population of the region was 1,123,307 in 2016; however, this number does not include large numbers of seasonal cottage country residents, which at peak times of the year swell its population to well in excess of 1.5 million. Although it contains many small and medium-sized urban centres, much of Central Ontario is covered by farms, lakes (with freshwater beaches), rivers or sparsely populated forested land on the southern edge of the Canadian Shield.Geography of Canada
The geography of Canada describes the geographic features of Canada, the world's second largest country in total area.
Situated in northern North America (constituting 41% of the continent's area), Canada spans a vast, diverse territory between the North Pacific Ocean to the west and the North Atlantic Ocean to the east and the Arctic Ocean to the north (hence the country's motto "From sea to sea"), with the United States to the south (contiguous United States) and northwest (Alaska). Greenland is to the northeast; off the southern coast of Newfoundland lies Saint Pierre and Miquelon, an overseas collectivity of France. Since 1925, Canada has claimed the portion of the Arctic between 60°W and 141°W longitude to the North Pole; however, this claim is contested. While the magnetic North Pole lies within the Canadian Arctic territorial claim as of 2011, recent measurements indicate it is moving towards Siberia.Covering 9,984,670 km2 or 3,855,100 sq mi (land: 9,093,507 km2 or 3,511,023 sq mi; freshwater: 891,163 km2 or 344,080 sq mi), Canada is slightly less than three-fifths as large as Russia and slightly smaller than Europe. In total area, Canada is slightly larger than both the U.S. and China; however, Canada ranks fourth in land area (i.e. total area minus the area of lakes and rivers)—China is 9,326,410 km2 (3,600,950 sq mi) and the U.S. is 9,161,923 km2 (3,537,438 sq mi).The population of Canada, 35,151,728 as of May 10, 2016, is concentrated in the south close to its border with the contiguous U.S.; with a population density of 3.5 people per square kilometre (9.1/sq mi), it is one of the most sparsely populated countries in the world. The northernmost settlement in Canada—and in the world—is Canadian Forces Station (CFS) Alert (just north of Alert, Nunavut) on the northern tip of Ellesmere Island at 82°30′N 62°19′W, just 834 kilometres (518 mi) from the North Pole.Geography of Saskatchewan
The geography of Saskatchewan (suskăchuwun"), is unique among the provinces and territories of Canada in some respects. It is one of only two landlocked regions (Alberta is the other) and it is the only region whose borders are not based on natural features like lakes, rivers or drainage divides. The borders of Saskatchewan, which make it very nearly a trapezoid, were determined in 1905 when it became a Canadian province. Saskatchewan has a total area of 651,036 square kilometres (251,366 sq mi) of which 591,670 km2 (228,450 sq mi) is land and 59,366 km2 (22,921 sq mi) is water.The province's name comes from the Saskatchewan River, whose Cree name is: kisiskatchewani sipi, meaning "swift flowing river".Saskatchewan can be divided into three regions: grassland (part of the Great Plains) in the south, aspen parkland in the center, and forest (taiga) in the north, part of the Canadian Shield. Its principal rivers are the Assiniboine River, and North and South Saskatchewan Rivers.
Saskatchewan is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, and on the south by the U.S. states of Montana and North Dakota.Georgian Bay Islands National Park
Georgian Bay Islands National Park (established 1929) consists of 63 small islands or parts of islands in Georgian Bay, near Port Severn, Ontario. The total park area is approximately 13.5 km2 (5.2 sq mi). Prior to the creation of Fathom Five National Marine Park, Flowerpot Island was also a part of the park.The islands blend the exposed rocks and pines of the Canadian Shield with the hardwood forests found further south. The park can only be reached by boat; there are limited camping facilities on the largest island, Beausoleil Island.
It is part of the Georgian Bay Littoral Biosphere Reserve.Indigenous peoples of the Subarctic
Indigenous peoples of the Subarctic are the aboriginal peoples who live in the Subarctic regions of the Americas, Asia and Europe, located south of the true Arctic. This region includes the interior of Alaska, the Western Subarctic or western Canadian Shield and Mackenzie River drainage area, the Eastern Subarctic or Eastern Canadian Shield, Scandinavia, Western Russia and East Asia. Peoples of subarctic Siberia and Greenland are included in the subarctic; however, Greenlandic Inuit are usually classified as Indigenous peoples of the Arctic.Interior Plains
The Interior Plains is a vast physiographic region that spreads across the Laurentian craton of central North America. The region extends from the Gulf Coast region to the Arctic Ocean along the east flank of the Rocky Mountains. In Canada the region separates the Rocky Mountains from the Canadian Shield. In the United States the plains include the Great Plains of the west and the Tallgrass prairie region to the south of the Great Lakes extending east to the Appalachian Plateau region.Kawartha Lakes Road 35
Kawartha Lakes Road 35, also known as Victoria Road and Fennel Road, is a municipally-maintained road located in the city of Kawartha Lakes, in the Canadian province of Ontario. The road is mostly straight, running in a north–south orientation throughout its length. It began at the hamlet of Glenarm and travels 30.5 kilometres (19.0 mi) to Uphill.
The road was constructed in the 1850s as the Victoria Colonization Road in an effort to settle the southern fringe of the Canadian Shield. The northern half was designated as Secondary Highway 505 until 1998, when it became part of Kawartha Lakes Road 35.Laurentian Upland
The Laurentian Upland (or Laurentian Highlands) is a physiographic region which, when referred to as the "Laurentian Region" or the Grenville geological province, is recognized by Natural Resources Canada as one of five provinces of the larger Canadian Shield physiographic division. The United States Geological Survey recognizes the Laurentian Upland as the larger general upland area of the Canadian Shield.Mackenzie dike swarm
The Mackenzie dike swarm, also called the Mackenzie dikes, form a large igneous province in the western Canadian Shield of Canada. It is part of the larger Mackenzie Large Igneous Province and is one of more than three dozen dike swarms in various parts of the Canadian Shield.
The Mackenzie dike swarm is the largest dike swarm known on Earth, more than 500 km (310 mi) wide and 3,000 km (1,900 mi) long, extending in a northwesterly direction across the whole of Canada from the Arctic to the Great Lakes. The mafic dikes cut Archean and Proterozoic rocks, including those in the Athabasca Basin in Saskatchewan, Thelon Basin in Nunavut and the Baker Lake Basin in the Northwest Territories.
The source for the Mackenzie dike swarm is considered to have been a mantle plume center called the Mackenzie hotspot. About 1,268 million years ago, the Slave craton was partly uplifted and intruded by the giant Mackenzie dike swarm. This was the last major event to affect the core of the Slave craton, although later on some younger mafic magmatism registered along its edges.Midwestern Canadian Shield forests
The Midwestern Canadian Shield forests ecoregion, in the Taiga and Boreal forests Biome, are of northern Canada.Nearctic realm
The Nearctic is one of the eight biogeographic realms constituting the Earth's land surface.
The Nearctic realm covers most of North America, including Greenland, Central Florida, and the highlands of Mexico. The parts of North America that are not in the Nearctic realm are Eastern Mexico, Southern Florida, coastal Central Florida, Central America, and the Caribbean islands which are part of the Neotropical realm, together with South America.Northern Highland
The Northern Highland is a geographical region in the north central United States covering much of the northern territory of the state of Wisconsin.
The region stretches from the state border with Minnesota in the west to the Michigan border in the east, and from Douglas and Bayfield Counties in the north to Wood and Portage Counties in the south. While most of northern Wisconsin is within the Northern Highland region, a short belt of land along the coast of Lake Superior is not included in the area, and is instead part of the Lake Superior Lowland. Outside Wisconsin the highland stretches northward in Canada through the Upper Peninsula of Michigan and the Canadian Shield in Northern Ontario and Quebec to Labrador and Hudson Bay.Saint Lawrence Lowlands
The Great Lakes-St.
Lawrence Lowlands is a bowl-shaped landform located near to the Great Lakes excluding Lake shed the land in the area downwards, depositing soil deeper into the earth, With this process no longer in effect, the deposited soil and land is currently rising up).
The Great Lakes basin area effectively became a lake after the ice sheet melted. However, due to the presence of a deep fault line, all of this water was eventually siphoned into the ocean. Thus, the primary defining historic feature of the lowlands the presence of deep soils within the watershed and estuary of the St. Lawrence River. This feature occurs in more than one distinct Peninsular Ontario south and west of and the surrounding area, including the lower Ottawa Valley and the St. Lawrence below the Thousand Islands, as far as Quebec City. A narrow ribbon of land along both shores of the lower St Lawrence Estuary, hemmed in on the north shore by the Canadian Shield and on the south which faces into the flow of the river, has accreted alluvial soils from the Great lakes basin.
The lowlands are split into these sub-regions by intrusions from adjacent physiographic regions. Peninsular Ontario lowlands are separated from the lowlands of the lower St. Lawrence at the Thousand Islands by the geologic feature called the Frontenac Axis, where ancient granite of the Canadian Shield cross over and become the Adirondacks. The next notable pinching occurs at Quebec City, where again the Shield meets the shore. Anticosti Island and Newfoundland, both being islands, are separated by stretches of open salt water.
There are animals such as warblers, wolves, snowshoe hares, blue birds, white-tailed deer, red-winged black birds, coyotes, frogs, eagles, and beavers. It stretches from Windsor to Quebec City .Shield (geology)
A shield is generally a large area of exposed Precambrian crystalline igneous and high-grade metamorphic rocks that form tectonically stable areas. In all cases, the age of these rocks is greater than 570 million years and sometimes dates back 2 to 3.5 billion years. They have been little affected by tectonic events following the end of the Precambrian, and are relatively flat regions where mountain building, faulting, and other tectonic processes are greatly diminished compared with the activity that occurs at the margins of the shields and the boundaries between tectonic plates.
The term shield, used to describe this type of geographic region, appears in the 1901 English translation of Eduard Suess's Face of Earth by H. B. C. Sollas, and comes from the shape "not unlike a flat shield" of the Canadian Shield which has an outline that "suggests the shape of the shields carried by soldiers in the days of hand-to-hand combat."Shields occur on all continents.Superior Craton
The Superior Craton or Superior Province is an Archean craton (4.031 billion years ago-present) which forms the core of the Canadian Shield lying north of Lake Superior for which it is named.
The craton extends from northwestern Quebec along the east side of Hudson Bay south through Northern Ontario to the north shores of Lake Huron and Lake Superior. It extends across Northwestern Ontario south of Hudson Bay and underlies most of southeastern Manitoba. It extends southward through eastern North and South Dakota and western Minnesota.It is bounded on the west and north by the Proterozoic Trans-Hudson orogen which separates it from the Wyoming, Hearne, Slave, Rae and Nain cratons. On the southeast it is bounded by the Grenville Front and to the south by the Midcontinent Rift System and the Yavapai – Mazatzal terranes.Western Canadian Sedimentary Basin
The Western Canadian Sedimentary Basin (WCSB) is a vast sedimentary basin underlying 1,400,000 square kilometres (540,000 sq mi) of Western Canada including southwestern Manitoba, southern Saskatchewan, Alberta, northeastern British Columbia and the southwest corner of the Northwest Territories. It consists of a massive wedge of sedimentary rock extending from the Rocky Mountains in the west to the Canadian Shield in the east. This wedge is about 6 kilometres (3.7 mi) thick under the Rocky Mountains, but thins to zero at its eastern margins. The WCSB contains one of the world's largest reserves of petroleum and natural gas and supplies much of the North American market, producing more than 16,000,000,000 cubic feet (450,000,000 m3) per day of gas in 2000. It also has huge reserves of coal. Of the provinces and territories within the WCSB, Alberta has most of the oil and gas reserves and almost all of the oil sands.