NationMaster - Encyclopedia: Ediacaran

The Ediacaran Period (named after the Ediacara Hills of South Australia) is the last geological period of the Neoproterozoic Era, just preceding the Cambrian Period of the Paleozoic Era. Its status as an official geological period was ratified in March 2004 by the International Union of Geological Sciences (IUGS) and announced on May 13, 2004, the first new geological period declared in 120 years.^[1]^[2] The type section is in the Flinders Ranges in South Australia. It overlaps, but is shorter than the Vendian period, a name that was earlier proposed in Russia. Ediacara Hills is a hill range in the northern Flinders Ranges of South Australia, around 650km north of Adelaide. ... Capital Adelaide Government Constitutional monarchy Governor Marjorie Jackson-Nelson Premier Mike Rann (ALP) Federal representation - House seats 11 - Senate seats 12 Gross State Product (2004-05) - Product ($m) $59,819 (5th) - Product per capita $38,838/person (7th) Population (End of September 2006) - Population 1,558,200 (5th) - Density 1. ... The geologic time scale is used by geologists and other scientists to describe the timing and relationships between events that have occurred during the history of the Earth. ... The Neoproterozoic Era is the unit of geologic time from 1,000 to 542 +/- 0. ... The Cambrian is a major division of the geologic timescale that begins about 542 Â± 1. ... The Paleozoic Era (from the Greek palaio, old and zoion, animals, meaning ancient life) is the earliest of three geologic eras of the Phanerozoic eon. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... IUGS logo The International Union of Geological Sciences (IUGS) is an international non-governmental organization devoted to international cooperation in the field of geology. ... is the 133rd day of the year (134th in leap years) in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... A Global Boundary Stratotype Section and Point, abbreviated GSSP, is an internationally agreed upon stratigraphic section which serves as the reference section for a particular boundary on the geologic time scale. ... Flinders Ranges is a national park in South Australia (Australia), 384 km north of Adelaide. ...

Base of the Ediacaran

Although the Ediacaran Period does contain soft bodied fossils, it is unusual in comparison to later periods because its beginning is not defined by a change in the fossil record. Rather, the beginning is defined at the base of a chemically distinctive carbonate layer, referred to as a "cap carbonate", because it caps glacial deposits and indicates a sudden climatic change at the end of an ice age. This bed is characterized by an unusual depletion of ¹³C, and is considered by many scientists to be of global extent, although this is controversial. For other uses, see Fossil (disambiguation). ... It has been suggested that this article or section be merged into Fossil. ... In organic chemistry, a carbonate is a salt of carbonic acid. ... Cap carbonates are layers of distinctively textured carbonate rocks which typically form the uppermost layer of sedimentary sequences reflecting major glaciations in the geological record. ... Variations in CO2, temperature and dust from the Vostok ice core over the last 400 000 years For the animated movie, see Ice Age (movie). ...

Dating

No dating has been possible at the type section of the Ediacaran Period in South Australia. Therefore the age range of 635 to 542 million years before the present is based on correlations to other countries where dating has been possible. The base age of approximately 635 million years ago is based on U-Pb (uranium-lead) isochron dating from Namibia.^[3] Applying this age to the base of the Ediacaran assumes that individual cap carbonates are synchronous around the world and that the correct cap carbonate layers have been correlated between Australian and Namibia. This is controversial because an age of about 580 million years has been obtained in association with glacial rocks in Tasmania which some scientists tentatively correlate with those just beneath the Ediacaran rocks of the Flinders Ranges.^[4] The age of the top is the same as the widely recognised age for the base of the Cambrian Period.^[2] Absolute dating is the process of determining a specific archaeological date. ... General Name, symbol, number uranium, U, 92 Chemical series actinides Group, period, block n/a, 7, f Appearance silvery gray metallic; corrodes to a spalling black oxide coat in air Standard atomic weight 238. ... For Pb as an abbreviation, see PB. General Name, Symbol, Number lead, Pb, 82 Chemical series Post-transition metals or poor metals Group, Period, Block 14, 6, p Appearance bluish gray Standard atomic weight 207. ... Iscochron dating is a type of radiometric dating. ... Slogan or Nickname: The Apple Isle; Holiday Isle Motto(s): Ubertas et Fidelitas (Fertility and Faithfulness) Other Australian states and territories Capital Hobart Government Constitutional monarchy Governor William Cox Premier Paul Lennon (ALP) Federal representation - House seats 5 - Senate seats 12 Gross State Product (2004-05) - Product ($m) $16,114... The Cambrian is a major division of the geologic timescale that begins about 542 Â± 1. ...

Biota

The animal fossil record from this period is sparse, possibly because animals had yet to evolve hard shells, which make for easier fossilization. The Ediacaran biota include the oldest definite multicellular organisms, and the most common types resemble segmented worms, fronds, disks, or immobile bags. They bear little resemblance to modern lifeforms, and their relationship even with the later lifeforms of the Cambrian explosion is difficult to interpret. More than 100 genera have been described, and well known forms include Arkarua, Charnia, Dickinsonia, Ediacaria, Marywadea, Onega, Pteridinium, and Yorgia. Dickinsonia costata, an Ediacaran organism of unknown affinity, with a quilted appearance. ... Wild-type Caenorhabditis elegans hermaphrodite stained to highlight the nuclei of all cells Multicellular organisms are organisms consisting of more than one cell, and having differentiated cells that perform specialized functions. ... For other uses, see Scientific classification (disambiguation). ... The Cambrian explosion is the geologically kukko sudden appearance in the fossil record of the ancestors of familiar animals, starting about 542 million years ago (Mya). ... For other uses, see Genus (disambiguation). ... Arkaruais a small, Precambrian disk-like fossil with a raised center, a number of radial ridges on the rim, and a five-pointed central depression marked with radial lines of 5 small dots from the middle of the disk center. ... Species Charnia wardi Charnia masoni Charnia is the genus name given to a frond-like Precambrian lifeform with segmented ridges branching alternately to the right and left from a zig-zag medial suture. ... Species Dickinsonia is an ancient ovoid fossil with somewhat radial tubes from a (sometimes missing) central ridge. ... Ediacaria is a medusoid fossil from the Precambrian Era, or more precisely the Ediacaran Period. ... Marywadea is an Ediacaran fossil. ... Onega stepanovi is a fossil from the Ediacaran Period, described by Fedonkin in 1976. ... Pteridinium is a fossil found in a number of Precambrian deposits worldwide. ... Yorgia waggoneri is a fossil from the Ediacaran period. ...

See also

List of fossil sites: // Afar Depression, Ethiopia, Pliocene Awash River, Afar Depression, Ethiopia, Australopithecus afarensis, Lucy, Pliocene, 3. ...

References

^ Knoll, A.H.; Walter, M.R., Narbonne, G.M., Christie-blick, N. (2004). "A new period for the geologic time scale". Science(Washington) 305 (5684): 621-622.
^ ^a ^b Ogg, J.G. (2004). "Status of Divisions of the International Geologic Time Scale". Lethaia 37 (2): 183-199. Retrieved on 2007-05-05.
^ Hoffmann, K.H.; Condon, D.J., Bowring, S.A., Crowley, J.L. (2004-09-01). "U-Pb zircon date from the Neoproterozoic Ghaub Formation, Namibia: Constraints on Marinoan glaciation". Geology 32 (9): 817-820. DOI:10.1130/G20519.1.
^ Calver, C.R.; Black, L.P., Everard, J.L., Seymour, D.B. (2004-10-01). "U-Pb zircon age constraints on late Neoproterozoic glaciation in Tasmania". Geology 32 (10): 893-896. DOI:10.1130/G20713.1.
^ Cite error 8; No text given.
^ Hofmann, H.J.; Narbonne, G.M., Aitken, J.D. (1990). "Ediacaran remains from intertillite beds in northwestern Canada". Geology 18 (12): 1199-1202.

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External links

Categories: Proterozoic | Fossils is the 5th day of the year in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... Catalyst is the current science-focused TV series which is made by the Australian Broadcasting Corporation (ABC). ... The Australian Broadcasting Corporation or ABC is Australias national non-profit public broadcaster. ... The Proterozoic (IPA: ) is a geological eon representing a period before the first abundant complex life on Earth. ... The Paleoproterozoic is the first of the three sub-divisions of the Proterozoic occurring between 2500 to 1600 million years ago. ... The Mesoproterozoic era is a geologic period that occurred between 1600 and 900 million years ago. ... The Neoproterozoic Era is the unit of geologic time from 1,000 to 542 +/- 0. ... The Siderian (from Greek sideros, iron) is the first geologic period in the Paleoproterozoic Era and lasted from 2500 million years ago to 2300 million years ago. ... From the GeoWhen Database: Rhyacian Period From 2300 +/- 0 To 2050 +/- 0 Ma Start Defined By: Fixed Date End Defined By: Fixed Date Start Based On: Gradstein, Ogg, Smith, et. ... The Orosirian (from Greek orosira, mountain range) is the third geologic period in the Paleoproterozoic Era and lasted from 2050 million years ago to 1800 million years ago. ... The Statherian (from Greek statheros, stable, firm) is the final geologic period in the Paleoproterozoic Era and lasted from 1800 million years ago to 1600 million years ago. ... The Calymmian (from Greek calymma, cover) is the first geologic period in the Mesoproterozoic Era and lasted from 1600 million years ago to 1400 million years ago. ... The Ectasian (from Greek ectsis, extension) is the second geologic period in the Mesoproterozoic Era and lasted from 1400 million years ago to 1200 million years ago. ... The Stenian (from Greek stenos, narrow) is the final geologic period in the Mesoproterozoic Era and lasted from 1200 million years ago to 1000 million years ago. ... The Tonian (from Greek tonas, stretch) is the first geologic period in the Neoproterozoic Era and lasted from 1000 Ma to 850 Ma (million years ago). ... The Cryogenian Period (from Greek cryos ice and genesis birth) is the second geologic period of the Neoproterozoic Era, followed by the Ediacaran Period. ... Image File history File links Commons-logo. ...

Contents

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