Global Boundary Stratotype Section and Point

A Global Boundary Stratotype Section and Point (GSSP) is a designated point in a physical rock section that defines the start of a geological time unit. It is marked by a specific event or feature and serves as its worldwide reference.

Stratotype: A designated rock succession or point used as a reference for defining and comparing stratigraphic units. A GSSP is a point within a stratotype section, selected to define a time boundary.
Chronostratigraphy: The branch of stratigraphy that organizes and correlates rock layers according to their formation time. GSSPs define the boundaries of chronostratigraphic units.
International Commission on Stratigraphy: The scientific organization responsible for developing and maintaining international stratigraphic standards. Its working groups evaluate and recommend GSSPs for formal ratification.
Ediacaran–Cambrian boundary GSSP: The GSSP defining the base of the Cambrian Period at Fortune Head in Newfoundland, Canada. Its defining section illustrates how fossil evidence can anchor a major period boundary.
Global stratotype section and point: A designated physical reference section and point used to define a stratigraphic boundary, commonly abbreviated GSSP. The name is often expanded differently, but the GSSP standard retains the same defining role.
Golden spike: A marker, often a literal brass plaque, commemorating a formally ratified GSSP. The marker identifies the exact boundary point in the field.
Geologic time scale: A system dividing Earth's history into nested units arranged from oldest to youngest. GSSPs provide physical reference points for boundaries on this time scale.
International Union of Geological Sciences: An international organization that coordinates geological sciences and approves major stratigraphic standards. It formally ratifies GSSP proposals endorsed by the stratigraphic commission.
Permian–Triassic boundary GSSP: The GSSP defining the base of the Triassic at Meishan, China. It anchors a boundary associated with one of Earth's most severe mass extinctions.
Global standard stratigraphic age: A numerical age assigned to a boundary in the geological time scale, often abbreviated GSSA. A GSSA defines a boundary by a numerical age rather than a designated physical point.

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