Related Clues:
- Vast time period of 1 billion years
- 12,000,000,000 months
- Very long time unit (var.)
- At least two geological eras
- Cosmological stretch
- Geologist's time frame
- More than a millennium
- Big stretch of time
- Huge time period
- Last hour of the workday, seemingly
- Lo-o-ong stretch
- Extremely extended stretch
- L-o-o-n-g time
- Very long time taken in Cannae once
- Two or more eras of geological time