4.7.2 Episode (Episode)
4.7.2.1 Episode is the diachronous unit of highest formal rank. Størmer (1966) proposed "episode" as the formal geochronological unit corresponding to the chronostratigraphical chronozone. This isochronous unit of time is now called a chron (Section 4.2.7). Episode should only be used formally for diachronous periods represented by depositional units of high stratigraphical rank, e.g. group or supergroup, morphosuite or morphosupersuite. Episode can, for example, be used to denote the period covering depositions related to a single ice age. When "episode" is used in informal contexts, it is recommended that the word be ascribed a meaning corresponding to that which applies in formal usage.