List of Global Boundary Stratotype Sections and Points

This is a list of Global Boundary Stratotype Sections and Points. Since 1977, Global Boundary Stratotype Sections and Points (abbreviated GSSPs) are internationally agreed upon stratigraphic sections of rock which serve as references for boundaries on the geologic time scale. They are selected by the International Commission on Stratigraphy based on multiple factors, but their accessibility and the degree to which they are representative of the same boundary on sections worldwide are among the most important.

Since GSSPs require well-preserved sections of rock, and since most are defined by different stages of animal life, defining them becomes progressively more difficult as one goes further back in time. With one exception, [The Ediacaran period is the only Precambrian period bounded by a GSSP. The boundary is defined as the base of the Nuccaleena Formation at the Enorama Creek section of the central Flinders Ranges, Adelaide Rift Complex, Australia, which marks the beginning of an ice age 630 mya.] GSSPs are limited to the Phanerozoic eon, while the Precambrian is demaracated by fixed dates which do not reflect identifiable changes in the geologic record (Global Standard Stratigraphic Ages). By 2008, all but three stages of the Phanerozoic will be bounded by GSSPs. [According to the schedule prepared at the ICS meeting in Leuven, Belgium, September 2005. The three stages omitted are Two, Three, and Four of the Cambrian. cite web | url = http://www.stratigraphy.org/Leuven.pdf | title = GSSP completion time-line | format = PDF | accessdate = 2006-06-30]

Organization of this list

This list is divided first into the geologic eras of the Phanerozoic (the Cenozoic, the Mesozoic, and the Paleozoic) and then into the geologic periods of each era. Each period has its own table, in which it is subdivided into epochs and stages. Each stage is assigned an age in mya, an acronym for million years ago, which is the age at which it began. Most of these ages are derived from astronomical cycles in sediments, magnetic data, biostratigraphic data, and radiometric dating methods. The GSSP assigned to each stage is that stage's lower boundary and oldest point.

The "Defining markers" column lists the evidence in the rock used to define the boundary. (Ideally, these are applicable in rock sections worldwide.) Most of the boundaries rely on the fossil record (biologic), paleomagnetic data (magnetic), and/or climate data determined by carbon and oxygen isotopes.

Cenozoic

Neogene

Jurassic

Carboniferous

Ordovician

Cambrian

Notes

References

*
*
*