Supereon

Supereon is an informal term sometimes used to describe a time interval that is larger than a geologic eon. It is not an officially defined unit in the standard geologic time scale, and no formal boundaries or durations are recognized by the International Commission on Stratigraphy. The term appears mainly in speculative writing, popular science, and some science fiction, where it serves as a way to discuss extremely long-term evolutionary processes beyond the scope of conventional time units.

Because eons themselves already span hundreds of millions to billions of years, a supereon is typically imagined as encompassing multiple eons and possibly several eras within a broad evolutionary arc. However, there is no consensus on its exact duration, and different authors may assign different scales to it. In some uses, the term functions more as a rhetorical or narrative device than as a precise measurement.

In general discussions, supereon is contrasted with the formal geologic time units: eon, era, period, epoch, and age. In cosmology and long-term planetary or biological forecasting, supereon-like terminology may appear when describing eras far beyond the present, although such usage remains informal. The lack of standardization means the concept can be interpreted variably across works, limiting its utility for rigorous scientific analysis but preserving its value as a heuristic for thinking about extremely long cosmic or planetary histories. See also: geologic time scale, eon, era, epoch, cosmology.