THE QUEST FOR PRECISION IN STRATIGRAPHY AND THE QUANTIFICATION OF STRATIGRAPHIC UNCERTAINTY

21^st-Century geoscience pursuits require an increasingly precise resolution of the stratigraphic record. Modern efforts to decipher past cause-and-effect relationships operating within the ancient Earth-Life System require a high-resolution stratigraphic and temporal framework and this need will only continue to grow in the future. The Geologic Time Scale lies at the intersection of geochronometry and chronostratigraphy and must integrate the rapid advances taking place within both the radioisotope community as well as the chronostratigraphic community. Traditionally however, these two communities have not been closely integrated.

The ability to determine uncertainty is a critical component to the analysis of precision within any system and is a major roadblock to increasing the resolution of the stratigraphic record as well as numerically calibrating the stratigraphic record. The application of a numerical plus/minus estimate of uncertainty is common practice when discussing a numerical age date, but the concept of temporal uncertainty as it pertains to chronostratigraphic correlation is more difficult to address. First, this is an integration of two manifestly separate concepts (rocks and time). Secondly, there is no appropriate language developed to address this issue. The question is one of temporal precision however it is a measure of the temporal precision of chronostratigraphic correlation.

This issue becomes most apparent when attempting to calibrate numerical ages of stage boundaries in the Geologic Time Scale. The majority of GSSPs do not contain dateable material and the best available radioisotopic data often have to be projected into the GSSP section to provide numerical calibration. With the increased precision of radioisotopic dating methods during the past decade, it has now reached a point where the temporal uncertainty of the chronostratigraphic correlation that projects the age date into the section is often larger than the temporal uncertainty of the numerical age date itself. As a result, chronostratigraphic uncertainty is now larger than geochronometric uncertainty for much of the Paleozoic. It is only through efforts to quantify chronostratigraphic uncertainty that we can begin to address this issue and ultimately improve the resolution of the global stratigraphic record.