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Tyrrell Sea
The Tyrrell Sea, named after Canada, Canadian geologist Joseph Tyrrell, is another name for prehistoric Hudson Bay, namely as it existed during the retreat of the Laurentide Ice Sheet. Roughly 8,000 years before present, BP, the Laurentide Ice Sheet thinned and split into two lobes, one centred over Quebec-Labrador, the other over District of Keewatin, Keewatin. This drained Glacial Lake Ojibway, a massive proglacial lake south of the ice sheet, leading to the formation of the early Tyrrell Sea. The weight of the ice had isostasy, isostatically depressed the surface as much as 270-280 metres, m below its current level, making the Tyrrell Sea much larger than modern Hudson Bay. Indeed, in some places the shoreline was 100 to 250 km farther inland than at present."Geomorphology From Spac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canada
Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by total area. Its southern and western border with the United States, stretching , is the world's longest binational land border. Canada's capital is Ottawa, and its three largest metropolitan areas are Toronto, Montreal, and Vancouver. Indigenous peoples have continuously inhabited what is now Canada for thousands of years. Beginning in the 16th century, British and French expeditions explored and later settled along the Atlantic coast. As a consequence of various armed conflicts, France ceded nearly all of its colonies in North America in 1763. In 1867, with the union of three British North American colonies through Confederation, Canada was formed as a federal dominion of four provinces. This began an accretion of provinces an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proglacial Lake
In geology, a proglacial lake is a lake formed either by the damming action of a moraine during the retreat of a melting glacier, a glacial ice dam, or by meltwater trapped against an ice sheet due to isostatic depression of the crust around the ice. At the end of the last ice age about 10,000 years ago, large proglacial lakes were a widespread feature in the northern hemisphere. Moraine-dammed The receding glaciers of the tropical Andes have formed a number of proglacial lakes, especially in the Cordillera Blanca of Peru, where 70% of all tropical glaciers are. Several such lakes have formed rapidly during the 20th century. These lakes may burst, creating a hazard for zones below. Many natural dams (usually moraines) containing the lake water have been reinforced with safety dams. Some 34 such dams have been built in the Cordillera Blanca to contain proglacial lakes. Several proglacial lakes have also formed in recent decades at the end of glaciers on the eastern side of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geology Of Canada
The geology of Canada is a subject of regional geology and covers the country of Canada, which is the second-largest country in the world. Geologic units and processes are investigated on a large scale to reach a synthesized picture of the geological development of the country. Geologically, Canada is one of the oldest regions in the world, with more than half of the region consisting of precambrian rocks that have been above sea level since the beginning of the Palaeozoic era. Canada's mineral resources are diverse and extensive. Across the Canadian Shield and in the north there are large iron, nickel, zinc, copper, gold, lead, molybdenum, and uranium reserves. Large diamond concentrations have been recently developed in the Arctic, making Canada one of the world's largest producers. Throughout the Shield there are many mining towns extracting these minerals. The largest, and best known, is Sudbury, Ontario. Sudbury is an exception to the normal process of forming minerals in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geology Of Ontario
The geology of Ontario consists of the study of the rock formations in the most populated province of Canada. Ontario has some of the oldest rocks on Earth. It is made up of ancient Precambrian igneous and metamorphic rock and overlain by younger sedimentary rocks and soils. About 61% of the province is covered by the Canadian Shield. The shield can further be divided into three sections or provinces. The northwestern parts of the Shield, located roughly north and west of Greater Sudbury, Sudbury, are known as the Superior province is the largest of the three sections, covering about 70% of the Shield portion in Ontario. The Southern Province (Canadian Shield), Southern province is a narrow region from Sault Ste. Marie, Ontario, Sault Ste. Marie to Kirkland Lake. The South central part is dominated by the Grenville Province but flanked by two basins of Phanerozoic materials. World-class mineral deposits can be found here and are mined extensively. Canadian Shield About 61% of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Historical Geology
Historical geology or palaeogeology is a discipline that uses the principles and methods of geology to reconstruct the geological history of Earth. Historical geology examines the vastness of geologic time, measured in billions of years, and investigates changes in the Earth, gradual and sudden, over this deep time. It focuses on geological processes, such as plate tectonics, that have changed the Earth's surface and subsurface over time and the use of methods including stratigraphy, structural geology, paleontology, and sedimentology to tell the sequence of these events. It also focuses on the evolution of life during different time periods in the geologic time scale. Historical development During the 17th century, Nicolas Steno was the first to observe and propose a number of basic principles of historical geology, including three key stratigraphic principles: the law of superposition, the principle of original horizontality, and the principle of lateral continuity. 18th-cent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sea Level Rise
Globally, sea levels are rising due to human-caused climate change. Between 1901 and 2018, the globally averaged sea level rose by , or 1–2 mm per year on average.IPCC, 2019Summary for Policymakers InIPCC Special Report on the Ocean and Cryosphere in a Changing Climate .-O. Pörtner, D.C. Roberts, V. Masson-Delmotte, P. Zhai, M. Tignor, E. Poloczanska, K. Mintenbeck, A. Alegría, M. Nicolai, A. Okem, J. Petzold, B. Rama, N.M. Weyer (eds.) Cambridge University Press, Cambridge, UK and New York, NY, USA. https://doi.org/10.1017/9781009157964.001. This rate is accelerating, with sea levels now rising by 3.7 mm per year. Climate scientists expect further acceleration during the 21st century. Climate change heats (and therefore expands) the ocean and melts land-based ice sheets and glaciers. Between 1993 and 2018, the thermal expansion of water contributed 42% to sea level rise; melting of temperate glaciers, 21%; Greenland, 15%; and Antarctica, 8%. Over the next 2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Post-glacial Rebound
Post-glacial rebound (also called isostatic rebound or crustal rebound) is the rise of land masses after the removal of the huge weight of ice sheets during the last glacial period, which had caused isostatic depression. Post-glacial rebound and isostatic depression are phases of glacial isostasy (glacial isostatic adjustment, glacioisostasy), the deformation of the Earth's crust in response to changes in ice mass distribution. The direct raising effects of post-glacial rebound are readily apparent in parts of Northern Eurasia, Northern America, Patagonia, and Antarctica. However, through the processes of ''ocean siphoning'' and ''continental levering'', the effects of post-glacial rebound on sea level are felt globally far from the locations of current and former ice sheets.Milne, G.A., and J.X. Mitrovica (2008) ''Searching for eustasy in deglacial sea-level histories.'' Quaternary Science Reviews. 27:2292–2302. Overview During the last glacial period, much of northern E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metres
The metre (British spelling Despite the various English dialects spoken from country to country and within different regions of the same country, there are only slight regional variations in English orthography, the two most notable variations being British and America ...) or meter (American English, American spelling; American and British English spelling differences#-re, -er, see spelling differences) (from the French unit , from the Greek language, Greek noun , "measure"), symbol m, is the primary unit of length in the International System of Units (SI), though its metric prefix, prefixed forms are also used relatively frequently. The metre was originally defined in 1793 as one ten-millionth of the distance from the equator to the North Pole along a great circle, so the Earth's circumference is approximately km. In 1799, the metre was redefined in terms of a prototype metre bar (the actual bar used was changed in 1889). In 1960, the metre was redefined in term ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isostasy
Isostasy (Greek ''ísos'' "equal", ''stásis'' "standstill") or isostatic equilibrium is the state of gravitational equilibrium between Earth's crust (or lithosphere) and mantle such that the crust "floats" at an elevation that depends on its thickness and density. This concept is invoked to explain how different topographic heights can exist at Earth's surface. Although originally defined in terms of continental crust and mantle, it has subsequently been interpreted in terms of lithosphere and asthenosphere, particularly with respect to oceanic island volcanoes, such as the Hawaiian Islands. Although Earth is a dynamic system that responds to loads in many different ways, isostasy describes the important limiting case in which crust and mantle are in static equilibrium. Certain areas (such as the Himalayas and other convergent margins) are not in isostatic equilibrium and are not well described by isostatic models. The general term 'isostasy' was coined in 1882 by the America ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glacial Lake Ojibway
Lake Ojibway was a prehistoric lake in what is now northern Ontario and Quebec in Canada. Ojibway was the last of the great proglacial lakes of the last ice age. Comparable in size to Lake Agassiz (to which it was likely linked), and north of the Great Lakes, it was at its greatest extent c. 8,500 years BP. The former lakebed forms the modern Clay Belt, an area of fertile land. Lake Ojibway was relatively short-lived. The lake drained in what must have been a catastrophic and dramatic manner around 8,200 years BP. One hypothesis is that a weakening ice dam separating it from Hudson Bay broke, as the lake was roughly above sea level. A comparable mechanism produced the Missoula floods that created the channeled scablands of the Columbia River basin. A recent analysis states it has not been conclusively determined whether the lake drained by a breach of the ice dam, by water spilling over the glacier, or by a flood under the glacier. It is also not conclusively known whether th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geologist
A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes Earth and other terrestrial planets, as well as the processes that shape them. Geologists usually study geology, earth science, or geophysics, although backgrounds in physics, chemistry, biology, and other sciences are also useful. Field research (field work) is an important component of geology, although many subdisciplines incorporate laboratory and digitalized work. Geologists can be classified in a larger group of scientists, called geoscientists. Geologists work in the energy and mining sectors searching for natural resources such as petroleum, natural gas, precious and base metals. They are also in the forefront of preventing and mitigating damage from natural hazards and disasters such as earthquakes, volcanoes, tsunamis and landslides. Their studies are used to warn the general public of the occurrence of these events. Geologists are also important contributors to climate chan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
District Of Keewatin
The District of Keewatin was a territory of Canada and later an administrative district of the Northwest Territories. It was created in 1876 by the ''Keewatin Act'', and originally it covered a large area west of Hudson Bay. In 1905, it became a part of the Northwest Territories and in 1912, its southern parts were adjoined to the provinces of Manitoba and Ontario, leaving the remainder, now called the Keewatin Region, with a population of a few thousand people. On April 1, 1999, the Keewatin Region was formally dissolved, as Nunavut was created from eastern parts of the Northwest Territories, including all of Keewatin. The name "Keewatin" comes from Algonquian roots—either in Cree or in Ojibwe—both of which mean ''north wind'' in their respective languages. In Inuktitut, it was called —a name which persists as the Kivalliq Region in Nunavut. History as a territory, 1876–1905 The District of Keewatin was created by the passage of the ''Keewatin Act'' on October 7 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
