出典:Wiktionary
出典:Wikipedia
出典:『Wikipedia』 (2011/05/17 00:57 UTC 版)
A chronozone or chron is a slice of time that begins at a given identifiable event and ends at another. In the fossil record such tracer events are usually keyed to disappearance (extinction) of a widely distributed and rapidly changing species or the appearance of such a species in the geological record. Chronozones or chrons are used especially in the various disciplines related to geology, notably in stratigraphy where relative dating is employed.