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Marinoan
The Marinoan glaciation, sometimes also known as the Varanger glaciation, was a period of worldwide glaciation that lasted from approximately 650 to 632.3 ± 5.9 Ma (million years ago) during the Cryogenian period. This glaciation possibly covered the entire planet, in an event called the Snowball Earth. The end of the glaciation was caused by volcanic release of carbon dioxide and dissolution of gas hydrates and might have been hastened by the release of methane from equatorial permafrost. Origin of name and history of terminology The name is derived from the stratigraphic terminology of the Adelaide Geosyncline (Adelaide Rift Complex) in South Australia and is taken from the Adelaide suburb of Marino. The term Marinoan Series was first used in a 1950 paper by Douglas Mawson and Reg Sprigg to subdivide the Neoproterozoic rocks of the Adelaide area and encompassed all strata from the top of the Brighton Limestone to the base of the Cambrian. The corresponding time period ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snowball Earth
The Snowball Earth hypothesis proposes that, during one or more of Earth's icehouse climates, the planet's surface became entirely or nearly entirely frozen. It is believed that this occurred sometime before 650 M.Y.A. (million years ago) during the Cryogenian period. Proponents of the hypothesis argue that it best explains sedimentary deposits that are generally believed to be of glacial origin at tropical palaeolatitudes and other enigmatic features in the geological record. Opponents of the hypothesis contest the geological evidence for global glaciation and the geophysical feasibility of an ice- or slush-covered ocean, and they emphasize the difficulty of escaping an all-frozen condition. A number of unanswered questions remain, including whether Earth was a full snowball or a "slushball" with a thin equatorial band of open (or seasonally open) water. The snowball-Earth episodes are proposed to have occurred before the sudden radiation of multicellular bioforms kno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cryogenian
The Cryogenian (from grc, κρύος, krýos, meaning "cold" and , romanized: , meaning "birth") is a geologic period that lasted from . It forms the second geologic period of the Neoproterozoic Era, preceded by the Tonian Period and followed by the Ediacaran. Cryogenian was the time of drastic biosphere changes. After the previous Boring Billion years of stability, at the beginning of Cryogenian the severe Sturtian glaciation began, freezing the entire Earth in a planetary state known as a Snowball Earth. After 70 million years it ended, but was quickly followed by the Marinoan glaciation, which was also a global event. These events are the subject of much scientific controversy specifically over whether these glaciations covered the entire planet or a band of open sea survived near the equator (termed "slushball Earth"). Ratification The Cryogenian Period was ratified in 1990 by the International Commission on Stratigraphy. In contrast to most other time periods, the b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adelaide Geosyncline
The Adelaide Superbasin (previously known as the Adelaide Geosyncline and Adelaide Rift Complex) is a major Neoproterozoic to middle Cambrian geological province in central and south-east South Australia, western New South Wales, and western Victoria. The Adelaide Superbasin consists of a thick pile of sedimentary rocks and minor volcanic rocks that were deposited on the eastern margin of Australia during the time of breakup of the supercontinent Rodinia. A number of authors have noted the similarity in these sedimentary rocks with rocks found in western North America and have suggested that they were formerly adjacent to each other in Rodinia. This is one major correlation in the SWEAT (south-west USA against East Antarctica) reconstruction of Rodinia. Particularly notable events that are preserved in the rock record of the Adelaide Superbasin are the two Neoproterozoic Snowball Earth events (the Sturtian and Marinoan Glaciations), the Neoproterozoic Oxygenation Event, the E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ediacaran
The Ediacaran Period ( ) is a geological period that spans 96 million years from the end of the Cryogenian Period 635 million years ago (Mya), to the beginning of the Cambrian Period 538.8 Mya. It marks the end of the Proterozoic Eon, and the beginning of the Phanerozoic Eon. It is named after the Ediacara Hills of South Australia. The Ediacaran Period's status as an official geological period was ratified in 2004 by the International Union of Geological Sciences (IUGS), making it the first new geological period declared in 120 years. Although the period takes its name from the Ediacara Hills where geologist Reg Sprigg first discovered fossils of the eponymous Ediacaran biota in 1946, the type section is located in the bed of the Enorama Creek within Brachina Gorge in the Flinders Ranges of South Australia, at . The Ediacaran marks the first appearance of widespread multicellular fauna following the end of Snowball Earth glaciation events, the so-called Ediacaran bio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gaskiers Glaciation
The Gaskiers glaciation is a period of widespread glacial deposits (e.g. diamictites) that lasted under 340 thousand years, between 579.63 ± 0.15 and 579.88 ± 0.44 million years ago — i.e. late in the Ediacaran Period — making it the last major glacial event of the Precambrian.F. M. Gradstein, Gabi Ogg, Mark Schmitz, ''The Geologic Time Scale'', Elsevier, 2012, p. 428. It was also the last and the shortest of at least three major ice ages in the Neoproterozoic era. It is assumed that, in contrast to the Sturtian and Marinoan periods, it did not lead to global glaciation ("Snowball Earth"). Deposits attributed to the Gaskiers — assuming that they were all deposited at the same time — have been found on eight separate paleocontinents, in some cases occurring close to the equator (at a latitude of 10–30°). The 300 m-thick name-bearing section at Gaskiers (Newfoundland) is packed full of striated dropstones. Its values are very low (pushing ), consistent with a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian
The Cambrian Period ( ; sometimes symbolized Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ago (mya) to the beginning of the Ordovician Period mya. Its subdivisions, and its base, are somewhat in flux. The period was established as "Cambrian series" by Adam Sedgwick, who named it after Cambria, the Latin name for 'Cymru' (Wales), where Britain's Cambrian rocks are best exposed. Sedgwick identified the layer as part of his task, along with Roderick Murchison, to subdivide the large "Transition Series", although the two geologists disagreed for a while on the appropriate categorization. The Cambrian is unique in its unusually high proportion of sedimentary deposits, sites of exceptional preservation where "soft" parts of organisms are preserved as well as their more resistant shells. As a result, our understanding of the Cambrian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sturtian Glaciation
The Sturtian glaciation was a Snowball Earth glaciation, or perhaps multiple glaciations, during the Cryogenian Period when the Earth experienced repeated large-scale glaciations. The duration of the Sturtian glaciation has been variously defined, with dates ranging from 717 to 643 Ma. Stern ''et al.'' place the period at 715 to 680 Ma. According to Eyles and Young, "Glaciogenic rocks figure prominently in the Neoproterozoic stratigraphy of southeastern Australia and the northern Canadian Cordillera. The Sturtian glaciogenic succession (c. 740 Ma) unconformably overlies rocks of the Burra Group." The Sturtian succession includes two major diamictite-mudstone sequences which represent glacial advance and retreat cycles. It is stratigraphically correlated with the Rapitan Group of North America. The Sturtian is named after the Sturt Tillite, exposed in the Sturt River Gorge, near Bellevue Heights, South Australia South Australia (commonly abbreviated as SA) is a States and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neoproterozoic
The Neoproterozoic Era is the unit of geologic time from 1 billion to 538.8 million years ago. It is the last era of the Precambrian Supereon and the Proterozoic Eon; it is subdivided into the Tonian, Cryogenian, and Ediacaran periods. It is preceded by the Mesoproterozoic Era and succeeded by the Paleozoic Era of the Phanerozoic Eon. The most severe glaciation known in the geologic record occurred during the Cryogenian, when ice sheets may have reached the equator and formed a "Snowball Earth". The earliest fossils of complex multicellular life are found in the Ediacaran Period. These organisms make up the Ediacaran biota, including the oldest definitive animals in the fossil record. According to Rino and co-workers, the sum of the continental crust formed in the Pan-African orogeny and the Grenville orogeny makes the Neoproterozoic the period of Earth's history that has produced most continental crust. Geology At the onset of the Neoproterozoic the supercontinent Rod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brighton Limestone
Brighton () is a seaside resort and one of the two main areas of the City of Brighton and Hove in the county of East Sussex, England. It is located south of London. Archaeological evidence of settlement in the area dates back to the Bronze Age, Roman and Anglo-Saxon periods. The ancient settlement of "Brighthelmstone" was documented in the ''Domesday Book'' (1086). The town's importance grew in the Middle Ages as the Old Town developed, but it languished in the early modern period, affected by foreign attacks, storms, a suffering economy and a declining population. Brighton began to attract more visitors following improved road transport to London and becoming a boarding point for boats travelling to France. The town also developed in popularity as a health resort for sea bathing as a purported cure for illnesses. In the Georgian era, Brighton developed as a highly fashionable seaside resort, encouraged by the patronage of the Prince Regent, later King George IV, who spent mu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surface is made up of the ocean, dwarfing Earth's polar ice, lakes, and rivers. The remaining 29% of Earth's surface is land, consisting of continents and islands. Earth's surface layer is formed of several slowly moving tectonic plates, which interact to produce mountain ranges, volcanoes, and earthquakes. Earth's liquid outer core generates the magnetic field that shapes the magnetosphere of the Earth, deflecting destructive solar winds. The atmosphere of the Earth consists mostly of nitrogen and oxygen. Greenhouse gases in the atmosphere like carbon dioxide (CO2) trap a part of the energy from the Sun close to the surface. Water vapor is widely present in the atmosphere and forms clouds that cover most of the planet. More solar e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geologic Time Scale
The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronology (scientific branch of geology that aims to determine the age of rocks). It is used primarily by Earth scientists (including geologists, paleontologists, geophysicists, geochemists, and paleoclimatologists) to describe the timing and relationships of events in geologic history. The time scale has been developed through the study of rock layers and the observation of their relationships and identifying features such as lithologies, paleomagnetic properties, and fossils. The definition of standardized international units of geologic time is the responsibility of the International Commission on Stratigraphy (ICS), a constituent body of the International Union of Geological Sciences (IUGS), whose primary objective is to precisely de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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