Related Clues:
- Very, very long time, in geology
- Vast time period of 1 billion years
- 12,000,000,000 months
- At least two geological eras
- Cosmological stretch
- Geologist's time frame
- Astronomer's measures
- Big stretch of time
- Eternity, so to speak
- Huge time period
- Massive time periods
- Life spans of suns
- Last hour of the workday, seemingly
- Lo-o-ong stretch
- Extremely extended stretch