Canadian Shield - wikipedia Canadian Shield Canadian Shield Stratigraphic range : Precambrian Had'n Archean Proterozoic Pha. Type Shield Unit of North American craton Sub-units Laurentian Upland Kazan Area 8 000 000 km Location Region North America Country Canada United States 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, 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. Contents 1 Geographical extent 2 Geology 3 Ecology 4 Mining and economics 5 See also 6 References 7 Further reading Geographical extent 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 Supereon ( 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 ( see 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 southern peninsula between the Great Lakes, 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 km ( 3,088,817 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 underlying rock structure also includes Hudson Bay. Canadian Shield geography in the Flin Flon, Manitoba region. The lake in the background is Big Island Lake. Geology Weathered Precambrian pillow lava in the Temagami Greenstone Belt 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. Typical Canadian Shield : spruce, lakes, bogs, and rock. 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. Ecology 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. Typical landscape in a southern Ontario region with very few old growth trees, due to a history of logging and fires. Black River, Queen Elizabeth II Wildlands Provincial Park. 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. Mining and economics 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. Currently the Ekati and Diavik mines are actively mining kimberlite diamonds. See also Geography of Canada portal Athabasca Basin Platform Oldest rock Basement Platform basement Volcanology of Canada Glacial history of Minnesota References ^ Jump up to : The Atlas of Canada. `` Physiographic Regions Map '' ( JP2 ). Natural Resources Canada. Retrieved 2017 - 08 - 01. ^ Jump up to : Encyclopædia Britannica. `` Canadian Shield ''. Archived from the original on 2015 - 06 - 24. Retrieved 2009 - 02 - 10. Jump up ^ Stephen Marshak. Essentials of Geology. 3rd ed. Jump up ^ `` Canadian Shield Archived 2006 - 08 - 21 at the Wayback Machine. '' in Columbia Encyclopedia. 6th ed., 2005. Jump up ^ James - Abra, Erin. `` Canadian Shield ''. Canadian Encyclopedia. Archived from the original on 11 January 2018. Retrieved 24 January 2018. Jump up ^ Corrigan, D. ( 2008 ). `` Metallogeny and Tectonic Evolution of the Trans - Hudson Orogen '' ( PDF ). Archived from the original ( PDF ) on April 9, 2008. Retrieved 2008 - 03 - 05. Jump up ^ Peterson Field Guide to Geology of Eastern North America by Roberts, David & Roger Tory Peterson. Jump up ^ Alberta Heritage - Alberta Online Encyclopedia Archived 2010 - 12 - 08 at Archive - It - The Canadian Shield Region of Alberta Jump up ^ Tsuyoshi Iizuka, at al., Geology and Zircon Geochronolgy of the Acasta Gneiss Complex, Precambrian Research, 153 ( 2007 ) pp. 179 - 208 Jump up ^ Clark, Bruce W. ( 1999 ). `` Geologic History ''. Making Connections : Canada 's geography. Scarborough, Ontario : Prentice Hall Ginn Canada. p. 95. ISBN 0 - 13 - 012635 - 7. Jump up ^ Caldera Volcanoes Archived 2012 - 06 - 16 at WebCite Retrieved on 2007 - 07 - 20 Jump up ^ Mark Pilkington and Walter R. Roest, Removing varying directional trends in aeromagnetic data, Geophysics, vol. 63 no. 2 ( 1998 ), pp. 446 -- 453. Jump up ^ `` Barbeau Peak ''. Bivouac.com. Jump up ^ World Wildlife Fund ( 2001 ). `` Northern Canadian Shield taiga ''. WildWorld Ecoregion Profile. National Geographic Society. Archived from the original on 2010 - 03 - 08. Jump up ^ C. Michael Hogan ( 2008 ) Polar Bear : Ursus maritimus, Globaltwitcher.com, ed. Nicklas Stromberg Archived December 24, 2008, at the Wayback Machine. Jump up ^ 3 - D Magnetic Imaging using Conjugate Gradients : Temagami anomaly Archived 2009 - 07 - 11 at the Wayback Machine. Retrieved on 2008 - 03 - 12 Jump up ^ Norris, Jessica ( 2007 ). `` Report on the 2007 Diamond Drilling Program McClarty Lake Project, Manitoba '' ( PDF ). Aurora Geosciences Ltd. Archived from the original ( PDF ) on 2008 - 05 - 30. Retrieved 2008 - 02 - 22. Further reading Library resources about Canadian Shield Resources in your library Resources in other libraries Schwartzenberger, Tina ( 2005 ), The Canadian Shield, Weigl Educational ISBN 1 - 55388 - 141 - 9 Pazynych V.G. Formation of placer gold deposits in Canadian Shield during late Wisconsin glaciation Canada History Year list ( Timeline ) Pre-colonization New France ( 1534 -- 1763 ) British Canada ( 1763 -- 1867 ) Post-Confederation ( 1867 -- 1914 ) World Wars and Interwar Years ( 1914 -- 1945 ) Modern times : 1945 -- 1960 1960 -- 1981 1982 -- 1992 since 1992 Topics Constitutional Crown & Aboriginals Economic Etymology Former colonies & territories Immigration Military Monarchical National Historic Sites Persons of significance Territorial evolution Women Provinces and territories Provinces Alberta British Columbia Manitoba New Brunswick Newfoundland and Labrador Nova Scotia Ontario Prince Edward Island Quebec Saskatchewan Territories Northwest Territories Nunavut Yukon Government Law Constitution Monarch Governor General Parliament ( Senate House of Commons ) Prime Minister list Courts Supreme Court Military Local government Foreign relations Law enforcement Politics Elections LGBT rights 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overviews Index Outline Topics Research Bibliography Historiography Book Category Portal Continental glaciations General Canadian Shield Glacial history of Minnesota Lake Agassiz Lake Chicago Lake Tight Last Glacial Maximum Laurentide Ice Sheet List of prehistoric lakes Post-glacial rebound Proglacial lake Teays River Timeline of glaciation Landforms Erosional Fjord Glacial striae Ribbon lake Roche moutonnée Tunnel valley U-shaped valley Depositional Drumlin Drumlin field Erratic block Moraine Pulju moraine Rogen moraine Terminal moraine Till plain Veiki moraine Glacifluvial Diluvium Esker Giant current ripples Kame Kame delta Kettle hole Outwash fan Sandur North American places Canada Arrowhead Provincial Park, Ontario Big Rock ( glacial erratic ), Alberta Cypress Hills ( Canada ), Saskatchewan Eramosa River, Ontario Eskers Provincial Park, British Columbia Foothills Erratics Train, Alberta Lion 's Head Provincial Park, Ontario Origin of the Oak Ridges Moraine, Ontario Ovayok Territorial Park, Nunavut United States Chippewa Moraine State Recreation Area, Wisconsin Coteau des Prairies, South Dakota Devil 's Lake State Park, Wisconsin Glacial Lake Wisconsin, Wisconsin Glacial Lakes State Park, Minnesota Horicon Marsh State Wildlife Area, Wisconsin Ice Age Floods National Geologic Trail, Idaho, Oregon & Washington Ice Age National Scientific Reserve, Wisconsin Ice Age Trail, Wisconsin Interstate State Park, Minnesota & Wisconsin Kelleys Island, Ohio Kettle Moraine State Forest, Wisconsin Lake Bonneville, Utah Lake Lahontan, Nevada Lake Missoula, Montana Mill Bluff State Park, Wisconsin Oneida Lake, New York Two Creeks Buried Forest State Natural Area, Wisconsin Withrow Moraine and Jameson Lake Drumlin Field, Washington Yosemite National Park, California Eurasian and Antarctic places Antarctica Hardangerfjord Killary Harbour Lambert Glacier Monte Rosa Ross Ice Shelf Svalbard Time periods Illinoian Stage Interglacial Interstadial Last glacial period Little Ice Age Older Dryas Pleistocene Pre-Illinoian Stage Quaternary glaciation Sangamonian Stage Wisconsin glaciation Younger Dryas Category Physiographic regions and provinces ( list ) Africa African Alpine System ( Atlas Mountains ) African massive ( Sahara Mid-African ) South African Platform ( Kalahari Region Lunda Swell Matabele Upland Veldt High Karoo Damara -- Nama Upland Namib Desert Cape Mountains Natal Terrace Belt Mozambique Plain Madagascar ) East African Highlands Rift Valley Abyssinian Americas Appalachian Appalachian Highlands Arctic Lowlands Atlantic Plain Canadian Shield Hudson Bay Lowlands Innuitian Region Interior Highlands Interior Plains Intermontane Plateaus Pacific Mountain System Rocky Mountain System Sierra Madre System Baja California Peninsula Buried Ranges Central Meseta Gulf Coastal Lowlands Neovolcanic Plateau Chiapas -- Guatemala Highlands Gulf Coast Plain and Yucatán Peninsula Andean Mountain System Brazilian Highlands Guiana Shield Amazon Plain Orinoco Basin Paraná -- Paraguay Plain Patagonian Plateau Antarctica East Antarctica West Antarctica Australia West Australian Shield East Australian Shield East Australian Cordillera Eurasia Fenno - Scandian Shield Central European Uplands Alpine System Great European Plain Ural Mountains Middle East Eastern Highlands Fertile Crescent West Siberian Plain Central Siberian Upland Eastern Highlands Northern Asian Mountains North Indian Plain Himalayan Mountain System Deccan Plateau Central Asian Lowlands See also : Physical geography and Physiographic regions of the world Coordinates : 52 ° 00 ′ N 71 ° 00 ′ W ﻿ / ﻿ 52.000 ° N 71.000 ° W ﻿ / 52.000 ; - 71.000 GND : 4259101 - 6 LCCN : sh85019406 VIAF : 239998762 Retrieved from `` https://en.wikipedia.org/w/index.php?title=Canadian_Shield&oldid=840686771 '' Categories : Cratons Geology of North America Precambrian North America Regional geology Geology of Canada Geology of the United States Precambrian Canada Precambrian United States Stratigraphy of Canada Stratigraphy of the United States Geology of Ontario Geology of Michigan Geology of Quebec Geology of Minnesota Geology of Newfoundland and Labrador Geology of New York ( state ) Geology of Manitoba Geology of Saskatchewan Geology of Nunavut Geology of the Northwest Territories Geology of Alberta Geology of Greenland Physiographic regions of Canada Regions of the Subarctic Hidden categories : Webarchive template wayback links Webarchive template other archives Webarchive template webcite links Articles containing French - language text All articles with unsourced statements Articles with unsourced statements from March 2011 Articles with unsourced statements from October 2010 Wikipedia articles needing clarification from March 2009 Coordinates on Wikidata Wikipedia articles with GND identifiers Wikipedia articles with LCCN identifiers Wikipedia articles with VIAF identifiers Talk Contents About Wikipedia Languages Afrikaans Asturianu Беларуская Български Bosanski Català Čeština 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Question: when was the canadian shield formed what era
Answer: Proterozoic Eon