views updated

boundary stratotype A specified rock section within which the time line (‘golden spike’, boundary zone) occurs that marks the standard demarcation between chronostratigraphic units. In practice such time lines are usually based on either the appearance or the disappearance of a key species (see index fossil) or other taxon. Associated faunas and sediments may transgress zonal boundaries. The term ‘boundary stratotype’ has also been used in the sense of the time line itself.

boundary stratotype

Updated About encyclopedia.com content Print Article Share Article