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For the genus of metalmark butterflies, see Rodinia (butterfly). A genus (plural genera from Γένος Latin genus "descent family type gender" is a low-level Taxonomic The Riodinidae (or metalmarks) are a family of butterflies. The common name "metalmarks" refers to the small metallic-looking spots commonly The Riodinidae (or metalmarks) are a family of butterflies. The common name "metalmarks" refers to the small metallic-looking spots commonly

In geology, Rodinia (from the Russian родина, or "motherland") refers to one of the oldest known supercontinents, which contained most or all of Earth's then-current landmass. Geology (from Greek γη gê, "earth" and λόγος Logos, "speech" lit Russian ( transliteration:,) is the most geographically widespread language of Eurasia, the most widely spoken of the Slavic languages In Geology, a supercontinent is a Landmass comprising more than one Continental core or Craton. Paleomagnetic evidence provides clues to the paleolatitude of individual formations, but not to their longitude, which geologists have pieced together by comparing similar strata, often now widely dispersed. Paleomagnetism is the study of the record of the Earth's magnetic field preserved in various Magnetic Minerals through time

Contents

Lifetime

Geologic evidence suggests that Rodinia formed and broke apart in the Neoproterozoic, probably existing as a single continent from 1 billion years ago until it began to rift into eight smaller continents about 800 million years ago. The Neoproterozoic Era is the unit of geologic time from 1000 to 542 +/- 0 [1] It is thought to have been largely responsible for the cold climate of the Neoproterozoic era. The Snowball Earth Hypothesis as it was originally proposed]] Evidence The Snowball Earth hypothesis was originally devised to explain the apparent presence of

Formation

Rodinia began forming about 1. 3 billion years ago from three or four pre-existing continents, an event known as the Grenville orogeny. The Grenville orogeny was an episode of mountain-building ( Orogeny) associated with the assembly of the ancient Supercontinent Rodinia. [2] The absence of fossils of hard-shelled organisms and reliable paleomagnetic data make the movements of continents earlier in the Precambrian, prior to this event, uncertain. Paleomagnetism is the study of the record of the Earth's magnetic field preserved in various Magnetic Minerals through time The Precambrian ( Pre-Cambrian) is an informal name for the supereon comprising the eons of the Geologic timescale that came before the current (See Columbia for one possible reconstruction of an earlier supercontinent. Columbia is the name of one of the Earth's oldest Supercontinents It was first proposed by J )

The arrangement of Rodinia has been hypothesized using paleomagnetic data from the Seychelles islands and India and the Grenville mountain belts, which were formed by the Grenville orogeny and span multiple modern continents, as references. Seychelles (seɪˈʃɛl or /seɪˈʃɛlz/ in English and seʃɛl in French) officially the Republic of Seychelles (République des Seychelles Creole India, officially the Republic of India (भारत गणराज्य inc-Latn Bhārat Gaṇarājya; see also other Indian languages) is a country [1][2]

Although the details are disputed by paleogeographers, the continental cratons that formed Rodinia appear to have clustered around Laurentia (proto-North America), which constituted Rodinia's core. Palaeogeography (sometimes spelled paleogeography) is the study of what the Geography was in times past A craton ( Greek kratos / κρἀτος ( neut. "strength" is an old and stable part of the Continental crust that has survived Laurentia (also known as the North American craton) like all Craton land was created as continents moved about the surface of the Earth

It appears that the east coast of Laurentia lay adjacent to the west coast of South America, while a conjoined Australia and Antarctica seem to have lain against the proto-North American west coast. South America is a Continent of the Americas, situated entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a For a topic outline on this subject see List of basic Australia topics. A third craton, what would become north-central Africa, was caught in between these two colliding masses. [3].

Other cratons such as the Kalahari (southern Africa), the Congo (west-central Africa), and the San Francisco (southeastern South America), appear to have been separate from the rest of Rodinia.

Paleogeography

Rodinia's landmass was probably centered south of the equator. The equator (sometimes referred to colloquially as "the Line") is the intersection of the Earth 's surface with the plane perpendicular to the [4] Because Earth was at that time experiencing the Cryogenian period of glaciation, and temperatures were at least as cool as today, substantial areas of Rodinia may have been covered by glaciers or the southern polar ice cap. The Cryogenian (from Greek cryos "cold" and genesis "birth" is a Geologic period that lasted from. "Glacial" and "Glaciation" redirect here For the geological periods see Glacial period. "Glacial" and "Glaciation" redirect here For the geological periods see Glacial period. A polar ice cap is a high- Latitude region of a Planet or moon that is covered in Ice. The interior of the continent, being so distant from the temperature-moderating effects of the ocean, was probably seasonally extremely cold (see continental climate). Continental climate is a Climate that is characterized by Winter Temperatures cold enough to support a fixed period of Snow cover each Year It was surrounded by the superocean geologists are calling Mirovia (from mir, the Russian word for "globe"). A superocean is an Ocean which surrounds a Supercontinent. It is less commonly defined as any ocean larger than the current Pacific Ocean. Mirovia (from Russian мировой mirovoy, meaning "global" was an hypothesized paleo-ocean which may have been a global Ocean that surrounded

Cold temperatures may have been exaggerated during the early stages of continental rifting. Geothermal heating peaks in crust about to be rifted; and since warmer rocks are less dense, the crustal rocks rise up relative to their surroundings. Geothermal heating has been used since the time of the Roman Empire as a way of heating Buildings and Spas by utilizing sources of hot Water The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different This rising creates areas of higher altitude, where the air is cooler and ice is less likely to melt with changes in season, and it may explain the evidence of abundant glaciation in the Ediacaran period. The Ediacaran Period (ˌiːdiˈækərən named after the Ediacara Hills of South Australia) is the last geological period of the Neoproterozoic [5]

The eventual rifting of the continents created new oceans, and seafloor spreading, which produces warmer less-dense rock, probably increased sea level by displacing ocean water. Seafloor spreading occurs at Mid-ocean ridges where new Oceanic crust is formed through volcanic activity and then gradually moves away from the ridge The result was a greater number of shallower oceans.

The evaporation from these oceans may have increased rainfall, which, in turn, increased the weathering of exposed rock. Evaporation is the process by which Molecules in a Liquid state (e By inputting δ18O data into computer models, it has been shown that in conjunction with quick-weathering volcanic rock, this increased rainfall may have reduced greenhouse gas levels to below the threshold required to trigger the period of extreme glaciation known as Snowball Earth. Volcanic rock is an Igneous rock of volcanic origin Texture Volcanic rocks are usually fine-grained or Aphanitic to glassy in Greenhouse gases are gaseous constituents of the atmosphere bothnatural and anthropogenic that absorb and emit radiation at specific wavelengths within the spectrum of thermal infrared The Snowball Earth Hypothesis as it was originally proposed]] Evidence The Snowball Earth hypothesis was originally devised to explain the apparent presence of [6]

All of this tectonic activity also introduced into the marine environment biologically important nutrients, which may have played an important role in the development of the earliest animals. Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere

Separation

In contrast to Rodinia's formation, the movements of continental masses during and since its breakup are fairly well understood. Evidence of extensive lava flows and volcanic eruptions around the Precambrian-Cambrian boundary, especially in North America, suggest that Rodinia began to rift apart no later than 750 million years ago. The Precambrian ( Pre-Cambrian) is an informal name for the supereon comprising the eons of the Geologic timescale that came before the current The Cambrian is a geologic period and system that began about Ma (million years ago at the end of the Proterozoic eon and ended about Ma with [5] Other continents, including Baltica and Amazonia, rifted off Laurentia 600 to 550 million years ago, opening the Iapetus Ocean between them. Baltica redirects here For the Russian beer, see Baltika Breweries Baltica is a name applied by geologists to a late- Proterozoic, The Iapetus Ocean was an Ocean that existed in the Southern Hemisphere between Laurentia ( Scotland and North America) and Baltica The separation also led to the birth of Panthalassic Ocean (or Paleo-Pacific). Panthalassa ( Greek, meaning 'all seas' also known as the Panthalassic Ocean, was the vast global Ocean that surrounded the Supercontinent [1]

The eight continents that made up Rodinia later re-assembled into another global supercontinent called Pannotia and, after that, once more as Pangaea. Pannotia, first described by Ian W D Dalziel in 1997 is a hypothetical Supercontinent that existed from the Pan-African orogeny about 600 million years ago to the Pangaea, Pangæa or Pangea (pænˈdʒiːə from παν pan, meaning entire, and Γαῖα Gaea, meaning Earth in

See also

External links

References

  1. ^ a b c Torsvik, Trond H (May 2003). The supercontinent cycle describes the quasi-periodic aggregration and dispersal of Earth 's Continental crust. "The Rodinia jigsaw puzzle". Science 300 (5624): 1379.  
  2. ^ a b Rodinia. Retrieved on 2006-03-10. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 241 BC - First Punic War: Battle of the Aegates Islands - The Romans sink the Carthaginian fleet bringing
  3. ^ Scotese, Christopher R. . More Information About the Late Precambrian. Paleomap Project. Retrieved on 2006-03-10. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 241 BC - First Punic War: Battle of the Aegates Islands - The Romans sink the Carthaginian fleet bringing
  4. ^ Rodinia. Palaeos. Retrieved on 2006-03-10. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 241 BC - First Punic War: Battle of the Aegates Islands - The Romans sink the Carthaginian fleet bringing
  5. ^ a b McMenamin, Mark A. ; Dianna L. McMenamin [1990-01-15]. "The Rifting of Rodina", The Emergence of Animals. ISBN 0-231-06647-3.  
  6. ^ Donnadieu, Yannick; Yves Goddéris, Gilles Ramstein, Anne Nédélec, Joseph Meert (March 2004). "A 'snowball Earth' climate triggered by continental break-up through changes in runoff". Nature 428: 303-306. doi:10.1038/nature02408. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.  

Dictionary

Rodinia

-proper noun

  1. The world supercontinent that formed at the end of the Mesoproterozoic era, then broke into eight continents during the Neoproterozoic.
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