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Katian
The Katian is the second stage of the Upper Ordovician. It is preceded by the Sandbian and succeeded by the Hirnantian Stage. The Katian began million years ago and lasted for about 7.6 million years until the beginning of the Hirnantian million years ago. During the Katian the climate cooled which started the Late Ordovician glaciation. Naming The name Katian is derived from Katy Lake ( Atoka County, Oklahoma, United States). GSSP The GSSP of the Katian Stage is the Black Knob Ridge Section in southeastern Oklahoma (United States). It is an outcrop of the Womble Shale and the Bigfork Chert, the latter containing the lower boundary of the Katian. The lower boundary is defined as the first appearance datum of the graptolite Graptolites are a group of colonial animals, members of the subclass Graptolithina within the class Pterobranchia. These filter-feeding organisms are known chiefly from fossils found from the Middle Cambrian ( Miaolingian, Wuliuan) through t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Ordovician Glaciation
The Hirnantian glaciation, also known as the Andean-Saharan glaciation, Early Paleozoic Ice Age (EPIA), the Early Paleozoic Icehouse, the Late Ordovician glaciation, or the end-Ordovician glaciation, occurred during the Paleozoic from approximately 460 Ma to around 420 Ma, during the Late Ordovician and the Silurian period. The major glaciation during this period was formerly thought only to consist of the Hirnantian glaciation itself but has now been recognized as a longer, more gradual event, which began as early as the Darriwilian, and possibly even the Floian. Evidence of this glaciation can be seen in places such as Arabia, North Africa, South Africa, Brazil, Peru, Bolivia, Chile, Argentina, and Wyoming. More evidence derived from isotopic data is that during the Late Ordovician, tropical ocean temperatures were about 5 °C cooler than present day; this would have been a major factor that aided in the glaciation process. The Late Ordovician glaciation is widely consid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Katian
The Katian is the second stage of the Upper Ordovician. It is preceded by the Sandbian and succeeded by the Hirnantian Stage. The Katian began million years ago and lasted for about 7.6 million years until the beginning of the Hirnantian million years ago. During the Katian the climate cooled which started the Late Ordovician glaciation. Naming The name Katian is derived from Katy Lake ( Atoka County, Oklahoma, United States). GSSP The GSSP of the Katian Stage is the Black Knob Ridge Section in southeastern Oklahoma (United States). It is an outcrop of the Womble Shale and the Bigfork Chert, the latter containing the lower boundary of the Katian. The lower boundary is defined as the first appearance datum of the graptolite Graptolites are a group of colonial animals, members of the subclass Graptolithina within the class Pterobranchia. These filter-feeding organisms are known chiefly from fossils found from the Middle Cambrian ( Miaolingian, Wuliuan) through t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atoka County, Oklahoma
Atoka County is a county located in the U.S. state of Oklahoma. As of the 2020 census, the population was 14,143. Its county seat is Atoka. The county was formed before statehood from Choctaw Lands, and its name honors a Choctaw Chief named Atoka. The county is part of Choctaw Nation reservation lands. History The area forming Atoka County was part of the Choctaw Nation after the tribe was forced to relocate in the early 1830s to Indian Territory from its home in the Southeastern United States. Unlike the State of Oklahoma, whose county boundaries follow the precise north–south, east–west grid established with the state's township and range system, the Choctaw Nation established its internal divisions using easily recognizable landmarks, such as mountains and rivers, as borders. The territory of present-day Atoka County fell within the Pushmataha District, one of the three administrative super-regions comprising the Choctaw Nation. Within that district, it was in part ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sandbian
The Sandbian is the first stage of the Upper Ordovician. It follows the Darriwilian and is succeeded by the Katian. Its lower boundary is defined as the first appearance datum of the graptolite species '' Nemagraptus gracilis'' around million years ago. The Sandbian lasted for about 5.4 million years until the beginning of the Katian around million years ago. Naming The name Sandbian is derived from the village Södra Sandby (Lund Municipality, Skåne County, Sweden). The name was proposed in 2006. GSSP The GSSP of the Sandbian is the Fågelsång section () at Sularp Brook, east of Lund (Skåne, Sweden). It is an outcrop of shale and mudstone. The lower boundary of the Sandbian is defined as the first appearance datum of graptolite Graptolites are a group of colonial animals, members of the subclass Graptolithina within the class Pterobranchia. These filter-feeding organisms are known chiefly from fossils found from the Middle Cambrian ( Miaolingian, Wuliuan) thro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Ordovician
The Late Ordovician is the third and final epoch of the Ordovician period, lasting million years and spanning from around 458.2 to 443.1 million years ago. The rocks associated with this epoch are referred to as the Upper Ordovician Series. At this time, Western and Central Europe and North America collided to form Laurentia, while glaciers built up in Gondwana, which was positioned over the South Pole. This caused a drop in global temperatures, resulting in "ice house" conditions. For most of this time, life continued to flourish, but at and near the end of the period, there were mass-extinction events that seriously affected planktonic forms like conodonts, graptolites, and some groups of trilobites ( Agnostida and Pytchopariida, which completely died out, and the Asaphida which were much reduced). Brachiopods, bryozoans and echinoderms were also heavily affected, and the endocerid cephalopods died out completely, except for possible rare Silurian The Silurian ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Womble Shale
The Womble Shale is a Middle Ordovician geologic formation in the Ouachita Mountains of Arkansas and Oklahoma. First described in 1892, this unit was not named until 1909 by Albert Homer Purdue in his study of the Ouachita Mountains of Arkansas, where he named this unit as part of the upper Ouachita Shale and the Stringtown Shale. In 1918, U.S. Geological Survey geologist, Hugh Dinsmore Miser, replaced Purdue's nomenclature with the Womble Shale. Miser assigned the town of Womble (now called Norman) in Montgomery County, Arkansas as the type locality. As of 2017, a reference section for this unit has yet to be designated. Paleofauna Bryozoa * '' Rhinidictya'' Graptolites * '' Azygograptus'' * '' Brygraptus'' * '' Climacograptus'' : ''C. bicornis'' : ''C. bicornis var. peltifer'' : ''C. caudatus'' : ''C. parvus'' : ''C. pultifer'' * '' Cryptograptus'' : ''C. insectiformis'' : ''C. tricornis'' * '' Desmograptus'' * '' Dicellograptus'' : ''D. diapason'' : ''D. divaricatus'' : ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bigfork Chert
The Bigfork Chert is a Middle to Late Ordovician geologic formation in the Ouachita Mountains of Arkansas and Oklahoma. First described in 1892, this unit was not named until 1909 by Albert Homer Purdue in his study of the Ouachita Mountains of Arkansas. Purdue assigned the town of Big Fork in Montgomery County, Arkansas as the type locality, but did not designate a stratotype. As of 2017, a reference section for this unit has yet to be designated. The Bigfork Chert is known to produce planerite, turquoise, variscite, and wavellite minerals. Paleofauna Graptolites * '' Climacograptus'' : ''C. antiquus'' * '' Dicellograptus'' : ''D. divaricatus'' * '' Diplograptus'' : ''D. trifidus'' : ''D. vulgatus'' * '' Glyptograptus'' * '' Lasiograptus'' : ''L. flaccidus'' * '' Mesograptus'' : ''M. perexcavatus'' * '' Orthograptus'' : ''O. quadrimucronatus'' See also * List of fossiliferous stratigraphic units in Arkansas * Paleontology in Arkansas Paleontology in Arkansas refers to pal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wangjiawan
Wangjiawan () is a village in the municipality of Fenxiang Town () and part of the Yiling District (), which itself is a part of the Yichang () of Hubei province. Geology The geologic outcrop, the "Wangjiawan section" () it the official GSSP A Global Boundary Stratotype Section and Point (GSSP), sometimes referred to as a golden spike, is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundary of a stage on the geologic time scale. ... for the Hirnantian stage of the Upper Ordovician; it is located at . References Geography of Yichang Village-level divisions of Hubei {{Hubei-geo-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yichang
Yichang ( zh, s= ), Postal Map Romanization, alternatively romanized as Ichang, is a prefecture-level city located in western Hubei province, China. Yichang had a population of 3.92 million people at the 2022 census, making it the third most populous city in Hubei. The city is famous for the Three Gorges, the Three Gorges Dam and the Gezhouba Dam, all three of which are located in Yiling, Yichang, Yiling District, one of the city's districts. History In ancient times Yichang was known as Yiling. In 278 BC, during the Warring States period, the Qin (state), Qin general Bai Qi set fire to Yiling. In 222 AD, Yichang was also the site of the Battle of Yiling during the Three Kingdoms Period. Under the Qing Dynasty, Qing Guangxu Emperor, Yichang Treaty ports, was opened to foreign commerce as a trading port after the Qing and Great Britain agreed to the Chefoo Convention, which was signed by Sir Thomas Wade and Li Hongzhang in Yantai, Chefoo on 21 August 1876. The imperial government ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
China
China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after India, representing 17.4% of the world population. China spans the equivalent of five time zones and Borders of China, borders fourteen countries by land across an area of nearly , making it the list of countries and dependencies by area, third-largest country by land area. The country is divided into 33 Province-level divisions of China, province-level divisions: 22 provinces of China, provinces, 5 autonomous regions of China, autonomous regions, 4 direct-administered municipalities of China, municipalities, and 2 semi-autonomous special administrative regions. Beijing is the country's capital, while Shanghai is List of cities in China by population, its most populous city by urban area and largest financial center. Considered one of six ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
