The role of stratotypes in stratigraphy

An alternative method of attaching a name to a span of time involves what are here called nominal points, which are best used for the nominal definition of provincial biochronologic units with geographic names. While permitting much instability in our concept of a given biochron, the nominal point method does not suffer from the problem of potential temporal overlap inherent in the strict nominal stratotype approach. These distinctions should be made in future revisions of stratigraphic codes and guides.