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Huronian
The Huronian glaciation (or Makganyene glaciation) was a period where several Ice age, ice ages occurred during the deposition of the Huronian Supergroup, rather than a single continuous event as it is commonly misrepresented to be. The deposition of this group extended from 2.5 billion years ago (Giga annum, Gya) to 2.2 Gya, during the Siderian and Rhyacian periods of the Paleoproterozoic era. This led to the deposition of several diamictites. Most of the deposits of the Huronian are typical passive margin deposits in a marine setting. The diamictites within the Huronian are on par in thickness with Quaternary analogs. Evidence for the Huronian comes from glacial deposits identified within the stratigraphic record of the Huronian Supergroup. Within it are three distinct Geological formation, formations of diamictite, from the oldest to youngest, the Ramsay, Bruce, and Gowganda Formations. Although there are other glacial deposits recognized throughout the world, the Huroni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Huronian Supergroup
The Huronian Supergroup is a Proterozoic assemblage of geologic formations of the Superior craton of the Canadian Shield in Ontario and Quebec. It extends from west of the city of Sault Ste. Marie in the west to the Ontario-Quebec border to the east and is part of the Southern Geologic Province. Stratigraphy The Huronian Supergroup consists of four Groups. All the rocks are low grade metamorphic sedimentary rocks or igneous rocks. The four geologic groups that make up the Huronian are the Elliot Lake Group, Hough Lake Group, Quirke Lake Group, and the Cobalt Group (from oldest to youngest). Major glacial periods, Huronian glaciation, occurred at the beginning of the Hough Lake, Quirke Lake and Cobalt. Age The bulk of the Huronian Group consists of mostly metamorphosed sandstones and mudstones. Since there are no index fossils, the sedimentary rocks cannot be dated using fossils, like they can in Phanerozoic rocks. However, the base contains volcanics that have been d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice Age
An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and greenhouse periods, during which there are no glaciers on the planet. Earth is currently in the Quaternary glaciation. Individual pulses of cold climate within an ice age are termed ''glacial periods'' (or, alternatively, ''glacials, glaciations, glacial stages, stadials, stades'', or colloquially, ''ice ages''), and intermittent warm periods within an ice age are called '' interglacials'' or ''interstadials''. In glaciology, ''ice age'' implies the presence of extensive ice sheets in both northern and southern hemispheres. By this definition, Earth is currently in an interglacial period—the Holocene. The amount of anthropogenic greenhouse gases emitted into Earth's oceans and atmosphere is predicted to prevent the next glacial period for th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Great Oxygenation Event
The Great Oxidation Event (GOE), also called the Great Oxygenation Event, the Oxygen Catastrophe, the Oxygen Revolution, the Oxygen Crisis, or the Oxygen Holocaust, was a time interval during the Paleoproterozoic era when the Earth's atmosphere and the shallow ocean first experienced a rise in the amount of oxygen. This began approximately 2.460–2.426 Ga (billion years) ago, during the Siderian period, and ended approximately 2.060 Ga, during the Rhyacian. Geological, isotopic, and chemical evidence suggests that biologically-produced molecular oxygen (dioxygen, O2) started to accumulate in Earth's atmosphere and changed it from a weakly reducing atmosphere practically free of oxygen into an oxidizing atmosphere containing abundant oxygen, with oxygen levels being as high as 10% of their present atmospheric level by the end of the GOE. The sudden injection of toxic oxygen into an anaerobic biosphere may have caused the extinction of many existing anaerobic species o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthur Philemon Coleman
Arthur Philemon Coleman (April 4, 1852 – February 26, 1939) was a Canadian geologist and academic. Biography Born in Lachute, Quebec, the son of Rev. Francis Coleman and Emmeline Maria Adams, he received his Bachelor of Arts in 1876 and Master of Arts in 1880 from Victoria College in Cobourg, Ontario. He received a Ph.D. at the University of Breslau in 1881. Coleman joined the department of geology and natural history at Victoria College in 1882 as a Professor. From 1891 to 1901, he was a Professor of Geology at the School of Practical Science in Toronto. From 1893 to 1909, he was a geologist at the Bureau of Mines of the Government of Ontario. From 1901 to 1922, he was a Professor of Geology at the University of Toronto and was Dean of the Faculty of Arts from 1919 to 1922. From 1931 to 1934, he was a geologist with the Department of Mines of the Government of Ontario. In 1898, Coleman lead a field expedition with the intent of surveying resources, along with the Geologist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siderian
The Siderian Period (; grc, σίδηρος, sídēros, meaning "iron") is the first geologic period in the Paleoproterozoic Era and lasted from Ma to Ma (million years ago). Instead of being based on stratigraphy, these dates are defined chronometrically. The deposition of banded iron formations peaked early in this period. These iron rich formations were formed as anaerobic cyanobacteria produced waste oxygen that combined with iron, forming magnetite (Fe3O4, an iron oxide). This process removed iron from the Earth's oceans, presumably turning greenish seas clear. Eventually, with no remaining iron in the oceans to serve as an oxygen sink, the process allowed the buildup of an oxygen-rich atmosphere. This second, follow-on event is known as the oxygen catastrophe, which, some geologists believe triggered the Huronian glaciation The Huronian glaciation (or Makganyene glaciation) was a period where several ice ages occurred during the deposition of the Huronian Supergroup, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhyacian
The Rhyacian Period (; grc, ῥύαξ, translit=rhýax, meaning "stream of lava") is the second geologic period in the Paleoproterozoic Era and lasted from Mya to Mya (million years ago). Instead of being based on stratigraphy, these dates are defined chronometrically. The Bushveld Igneous Complex and some other similar intrusions formed during this period. The Huronian (Makganyene) global glaciation began at the start of the Rhyacian and lasted 100 million years. It lasted about 80% of this period. For the time interval from 2250 Ma to 2060 Ma, an alternative period based on stratigraphy rather than chronometry, named either the Jatulian or the Eukaryian, was suggested in the geological timescale review 2012 edited by Gradstein et al., but , this has not yet been officially adopted by the IUGS. The term Jatulian is, however, used in the regional stratigraphy of the Paleoproterozoic rocks of Fennoscandia. This is when the eukaryotes are thought to have originated from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Huron
Lake Huron ( ) is one of the five Great Lakes of North America. Hydrology, Hydrologically, it comprises the easterly portion of Lake Michigan–Huron, having the same surface elevation as Lake Michigan, to which it is connected by the , Straits of Mackinac. It is shared on the north and east by the Canadian province of Ontario and on the south and west by the U.S. state of Michigan. The name of the lake is derived from early French explorers who named it for the Wyandot people, Huron people inhabiting the region. The Huronian glaciation was named from evidence collected from Lake Huron region. The northern parts of the lake include the North Channel (Ontario), North Channel and Georgian Bay. Saginaw Bay is located in the southwest corner of the lake. The main inlet is the St. Marys River (Michigan–Ontario), St. Marys River, and the main outlet is the St. Clair River. Geography By surface area, Lake Huron is the second-largest of the Great Lakes, with a surface area of — ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Horizon (geology)
In geology, a horizon is either a bedding surface where there is marked change in the lithology within a sequence of sedimentary or volcanic rocks, or a distinctive layer or thin bed with a characteristic lithology or fossil content within a sequence. Examples of the former can include things such as volcanic eruptions as well as things such as meteorite impacts and tsunamis. Examples of the latter include things such as ice ages and other large climate events, as well as large but temporary geological features and changes such as inland oceans. In the interpretation of seismic reflection data, horizons are the reflectors (or seismic events) picked on individual profiles. These reflectors represent a change in rock properties across a boundary between two layers of rock, particularly seismic velocity and density. It can also represent changes in the density of the material and the composition of it and the pressure under which it was produced. Thus, not only do the properties change ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rifting
In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben with normal faulting and rift-flank uplifts mainly on one side. Where rifts remain above sea level they form a rift valley, which may be filled by water forming a rift lake. The axis of the rift area may contain volcanic rocks, and active volcanism is a part of many, but not all, active rift systems. Major rifts occur along the central axis of most mid-ocean ridges, where new oceanic crust and lithosphere is created along a divergent boundary between two tectonic plates. ''Failed rifts'' are the result of continental rifting that failed to continue to the point of break-up. Typically the transition from rifting to spreading develops at a triple junction where three converging rifts meet over a hotspot. Two of these evolve to the poin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tectonics
Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents known as cratons, and the ways in which the relatively rigid plates that constitute the Earth's outer shell interact with each other. Tectonics also provide a framework for understanding the earthquake and volcanic belts that directly affect much of the global population. Tectonic studies are important as guides for economic geologists searching for fossil fuels and ore deposits of metallic and nonmetallic resources. An understanding of tectonic principles is essential to geomorphologists to explain erosion patterns and other Earth surface features. Main types of tectonic regime Extensional tectonics Extensional tectonics is associated with the stretching and thinning of the crust or the lithosphere. This type of tectonics is found ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Griquatown, Northern Cape
Griekwastad is a country town in South Africa. It is sometimes still called Griquatown (the meaning of the town's name in Afrikaans), a name which is now considered historical. The town is in the Northern Cape Province of South Africa by road west from the city of Kimberley. It was the first town to be established in the country north of the Orange River. History In 1801 William Anderson and Cornelius Kramer, of the London Missionary Society, established a station among the Griqua at ''Leeuwenkuil''. The site proved too arid for cultivation. In about 1805 they moved the station to another spring further up the valley and called it ''Klaarwater''. Their second choice was little better than their first, and for many years a lack of water prevented any further development. The name of the settlement was changed later to Griquatown or ''Griekwastad'' in Afrikaans. They lived among a mixed nomadic community of the Chaguriqua tribe and "bastaards" (people of mixed origin) from Pike ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canadian Northern Territories
Within the geographical areas of Canada, the ten provinces and three territories are sub-national administrative divisions under the jurisdiction of the Canadian Constitution. In the 1867 Canadian Confederation, three provinces of British North America—New Brunswick, Nova Scotia, and the Province of Canada (which upon Confederation was divided into Ontario and Quebec)—united to form a federation, becoming a fully independent country over the next century. Over its history, Canada's international borders have changed several times as it has added territories and provinces, making it the world's second-largest country by area. The major difference between a Canadian province and a territory is that provinces receive their power and authority from the ''Constitution Act, 1867'' (formerly called the ''British North America Act, 1867''), whereas territorial governments are creatures of statute with powers delegated to them by the Parliament of Canada. The powers flowing from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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