A date that gives the time of an event only with reference to another event that is not worldwide in scale. It only indicates that one event occurred earlier or later than another. For instance, the observation that strata 2 is younger than strata 1 beneath it in a geological deposit does not provide information about how many years ago strata 2 was laid down. It only indicates its age relative to strata 1. In addition to the use of stratigraphy, relative dating methods include biostratigraphy and fluorine analysis dating. See chronometric date.