However, both disciplines work together hand in hand, to the point that they share the same system of naming rock layers and the time spans utilized to classify layers within a strata.
(The terminology is given in the table on the right.) For instance, with reference to the geologic time scale, the Upper Permian (Lopingian) lasted from 270.6 /- 0.7 Ma (Ma = millions of years ago) until somewhere between 250.1 /- 0.4 Ma (oldest known Triassic) and 260.4 /- 0.7 Ma (youngest known Lopingian)—a gap in known, dated fossil assemblages of nearly 10 Ma.
The science of geochronology is the prime tool used in the discipline of chronostratigraphy, which attempts to arrange the sequence and time of deposition of all rocks in a geological region, and eventually, the entire geologic record of the Earth.
The aim of chronostratigraphy is to give a meaningful age date to fossil assemblage intervals and interfaces, as well as to determine the geologic history of the Earth and extraterrestrial bodies.
These include some that establish a relative chronology in which occurrences can be placed in the correct sequence relative to one another or to some known succession of events.
Each isotopic system has particular properties that lend itself to be used in different circumstances, e.g.
Both disciplines work together hand in hand however, to the point where they share the same system of naming rock layers and the time spans utilized to classify layers within a stratum.
The science of geochronology is the prime tool used in the discipline of chronostratigraphy, which attempts to derive absolute age dates for all fossil assemblages and determine the geologic history of the Earth and extraterrestrial bodies.
Geochronology is different in application from biostratigraphy, which is the science of assigning sedimentary rocks to a known geological period via describing, cataloguing and comparing fossil floral and faunal assemblages.
Biostratigraphy does not directly provide an absolute age determination of a rock, but merely places it within an interval of time at which that fossil assemblage is known to have coexisted.