Global Standard Stratigraphic Age Article Index for
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Global Standard Stratigraphic Age




GSSAs are defined by the International Commission On Stratigraphy and are only used for time older that 630 million years ago. For more recent periods, a Global Boundary Stratotype Section And Point (GSSP) is used to define such boundaries. In contrast to GSSAs, GSSPs are based on important events and transitions within a particular Stratigraphic section. In older sections, there is insufficient Fossil Record or well preserved sections to identify the key events necessary for a GSSP so GSSAs are defined based on fixed dates.