Other meanings of Golden spike
Geology
A golden spike is a physical marker used to define the boundary between two geologic time stages, formally known as a Global Boundary Stratotype Section and Point (GSSP). These markers, often actual brass or gold-colored spikes driven into rock outcrops, serve as the internationally agreed reference points for the geologic time scale. The term originated in 1963 with the first GSSP, placed at the base of the Eocene epoch in Denmark. Today, over 70 GSSPs have been ratified by the International Commission on Stratigraphy, anchoring the divisions of Earth's history in observable rock layers.
A golden spike is the colloquial name for a Global Boundary Stratotype Section and Point (GSSP), an internationally agreed reference section that defines the lower boundary of a geologic stage. The GSSP is a specific point in a rock sequence that marks the onset of a new chronostratigraphic unit, such as a stage, series, or system. The marker is typically a brass or metal plaque, sometimes literally a spike, driven into the outcrop at the exact boundary horizon. The purpose is to provide a single, unambiguous standard for correlation worldwide, so that geologists can compare rock sequences from different regions against a common reference.
The concept of a GSSP was formalized in the 1960s by the International Commission on Stratigraphy (ICS), a body of the International Union of Geological Sciences. The first GSSP was established in 1963 at the base of the Eocene series in Denmark, at a section near the town of Stevns Klint. Since then, the ICS has ratified GSSPs for most Phanerozoic stages, with the Ediacaran–Cambrian boundary (541 million years ago) being the oldest ratified GSSP, placed in Newfoundland, Canada. The most recent GSSP, for the Holocene series, was ratified in 2018, using a Greenland ice core as the reference section.
To qualify as a GSSP, a section must meet strict criteria: it must be continuous, with no gaps in sedimentation; it must contain a clear, globally recognizable marker event, such as the first appearance of a fossil species or a magnetic polarity reversal; and it must be accessible for study. The boundary is defined by a 'golden spike' point, often coinciding with a specific horizon in the rock. The selection process involves international working groups, which propose candidate sections, followed by voting by the ICS subcommissions. The chosen section becomes the global standard, and all other sections are correlated to it.
While most GSSPs are in marine sedimentary rocks, some are in non-marine settings, such as the Permian–Triassic boundary in China, defined in a terrestrial section. The term 'golden spike' is also used informally for the marker at the base of the Anthropocene, though that proposal was rejected in 2024. Some GSSPs are not actually marked with a physical spike; instead, they are marked with a plaque or a bolt. The oldest GSSP, for the Ediacaran, is unique in that it is defined by a chemostratigraphic marker (a carbon isotope excursion) rather than a fossil. Additionally, the GSSP for the base of the Jurassic is located in a remote mountain section in Austria, and the one for the base of the Silurian is in Scotland, at a site that was once a quarry.
The term 'golden spike' is also used in railroad history for the ceremonial spike driven at the completion of the First Transcontinental Railroad in 1869, but in geology it refers exclusively to GSSPs.
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