GSSPS AND HIGH PRECISION TIMESCALES
Remane (2003) implied that without the precise definitions of lower Stage boundaries provided by GSSPs then stratigraphy could not be claim to be a science. A science also requires the use of the most precise measurements available for its purposes. In many large outcrop areas the necessary measurements have not been yet been made, thus current stratigraphy can be viewed as a patchily scientific discipline. One of the consequences of an imprecise time-scale is that some interesting questions about the Mesozoic and Paleozoic world, in particular, cannot be adequately investigated.
The widespread use of biostratigraphic markers for GSSP definition, dating and correlation, particularly in most of the Mesozoic and Paleozoic, may actually impede the attainment of high precision. Thus what is regarded as a fossil global First Appearance Datum (FAD) or a global Last Appearance Datum (LAD) are generally only of local extent and the age difference between a given FO (or LO) and the global FAD (or LAD) can be several m.y., with a corresponding low precision in dating and correlation.
These shortcomings inevitably lead to the next phase of the GSSP project – that of providing the most precise markers that can be used in dating and global correlation. This will probably require that those GSSPs defined by biostratigrapic markers alone to add one or more physico-chemical markers, such as magnetic reversals, isotopic excursions and the like, to their definitions because these markers are potentially much more precise.
Unfortunately, the effects of hiatuses, which are rarely discussed in timescale work, can also give rise to major uncertainties in dating. However, given enough data, currently available multi-dimensional graphic correlation programs can average out the effect of hiatuses and ameliorate the problems of missing or misidentified fossils. When combined with data from GSSPs, the results are likely to lead to major improvements in the Phanerozoic time-scale.