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Encyclopedia > Global Boundary Stratotype Section and Point

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 timescale. The effort to define GSSPs is conducted by the International Commission on Stratigraphy, a part of the International Union of Geological Sciences. Most, but not all, GSSPs are based on paleontological changes. Hence GSSPs are usually described in terms of transitions between different faunal stages, though far more faunal stages have been described than GSSPs. The GSSP definition effort commenced in 1977. As of 2004, 45 of the 96 GSSPs required have been approved. The geologic timescale is used by geologists and other scientists to describe the timing and relationships between events that have occured during the history of the Earth. ... The International Commission on Stratigraphy concerns itself with stratigraphy on a global scale. ... The International Union of Geological Sciences (IUGS) was founded in 1961 and is a Scientific Union member of the International Council for Science (ICSU), which it recognizes as the coordinating body for the international organization of science. ... A paleontologist carefully chips rock from a column of dinosaur vertebrae. ... Faunal stages are a subdivision of geologic time used primarily by paleontologists who study fossils rather than by geologists who study rock formations. ...


An ideal GSSP would

  • be accessible by public transit from a major airport
  • be accessible to research
  • be extensive enough to ensure future access
  • be easily related to other exposures worldwide
  • contain a radiometrically datable bed at the boundary, and
  • include well defined markers at the stage boundary that can be applied worldwide.

No GSSP is ideal. A taxi serving as a bus Public transport comprises all transport systems in which the passengers do not travel in their own vehicles. ... AirPort is a wireless networking protocol from Apple Computer designed for both Macintosh and PC computers. ...

Contents

Agreed-upon GSSPs

The Precambrian-Cambrian boundary GSSP at Fortune Head, Newfoundland is a typical GSSP. It is accessible by paved road and is set aside as a nature preserve. A continuous section is available from beds that are clearly Precambrian into beds that are clearly Cambrian. The boundary is set at the first appearance of a complex trace fossil Trichophycus pedum that is found worldwide. The Fortune Head GSSP is unlikely to be washed away or built over. Trichophycus pedum is less than ideal as a marker fossil as it is not found in every Cambrian sequence, and it is not assured that it is found at the same level in every exposure. But no other fossil is known that would be preferable. There is no radiometrically datable bed at the boundary at Fortune Head, but there is one slightly above the boundary in similar beds not very far away. The Precambrian or Cryptozoic is the period of the geologic timescale from the formation of Earth around 4500 million years before the present (BP) to the evolution of abundant macroscopic hard-shelled fossils, which marked the beginning of the Cambrian, some 542 million years BP. Remarkably little is known about... The Cambrian is a major division of the geologic timescale that begins about 542 million years before the present (BP) at the end of the Proterozoic eon_geology and ended about 490 million years BP with the beginning of the Ordovician period. ... This is about the island in Canada. ... Radiometric dating is a technique used to date materials based on a knowledge of the decay rates of naturally occurring isotopes, and the current abundances. ...


Once a GSSP boundary has been agreed upon, a "golden spike" is driven into the geologic section to mark the precise boundary for future geologists (though in practice the "spike" need neither be golden or an actual spike). The first stratigraphic boundary was defined in 1977 by identifying the Silurian-Devonian boundary with a bronze plaque at a locality called Klonk, northeast of the village of Suchomastyin in the Czech Republic. GSSPs are also sometimes referred to as Golden Spikes. Alternate use: The Silurians, a reptilian race from the science fiction series Doctor Who. The Silurian is a major division of the geologic timescale that extends from the end of the Ordovician period, about 439 million years before the present (BP), to the beginning of the Devonian period, about 408. ... The Devonian is a major division of the geologic timescale that extends from the end of the Silurian period (360 million years ago (mya)) to the beginning of the Mississippian subperiod of the Carboniferous (408. ... National motto: Truth prevails (Czech: Pravda vítězí) Official language Czech Capital Praha (Prague) President Václav Klaus Prime Minister Jiří Paroubek Area  - Total  - % water Ranked 114th 78,866 km² 2% Population  - Total (2003)  - Density Ranked 76th 10. ...


GSSAs

Because defining a GSSP depends on finding well-preserved geologic sections and indentifying key events, this task becomes more difficult as one goes farther back in time. Before 630 million years ago, boundaries on the geologic timescale are defined simply by reference to fixed dates, known as Global Standard Stratigraphic Ages.


External link

  • The Global Boundary Stratotype Section and Point (GSSP) (http://www.stratigraphy.org/over.htm): overview

Reference

  • Hedberg, H.D., (editor), International stratigraphic guide: A guide to stratigraphic classification, terminology, and procedure, New York, John Wiley and Sons, 1976

  Results from FactBites:
 
Overview (2078 words)
The philosophy behind the boundary stratotype or GSSP is to define a level in an outcrop section where time and rock coincide, and thus define successive stages with precisely defined criteria for their lower and upper limits in relative time.
The boundary stratotype very much relies on the notion that it is possible to arrive at accuracy in correlation through the use of events, like a geomagnetic reversal, a global change in a stable isotope value, or the evolutionary appearance of one or more prominent and widespread pelagic fossil taxa.
The definition of a boundary by its linear age is the consequence of the fact that the the Proterozoic now recognizes units of global stratigraphic subdivision, where the boundaries are defined in terms of the age in millions of years.
BIGpedia - GSSP - Encyclopedia and Dictionary Online (389 words)
GSSPs are internationally agreed to reference stratigraphic sections representing the boundaries for paleontologic faunal stages.
The first stratigraphic boundary was defined in 1977 by a boundary stratotype or 'golden spike' (actually a bronze plaque) identifying the Silurian-Devonian boundary, at a locality called Klonk, northeast of the village of Suchomastyin in the Czech Republic.
Once a GSSP boundary has been agreed upon, a literal golden spike is driven into the geologic section to mark the boundary for future geologists.
  More results at FactBites »

 
 

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