chrone

CONT: Geologic time units have traditionally been presented in a hierarchical scheme with ranks: eon, era, period, epoch, ... age, chron.
OBS: 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 [and] chrons are used especially in the various disciplines related to Geology, notably in stratigraphy where relative dating is employed.

OBS: En la escala geocronológica, el cron corresponde a la cronozona de la escala estratigráfica.
OBS: El cron es la subdivisión de la edad geológica.