Related Clues:
- Gobs of time
- Historical episodes
- Time-line divisions
- Geologic succession
- Long reigns, e.g.
- Prominent periods of history
- Unimaginably long stretches
- Earth's age, perhaps
- Distinctive periods of history
- Geologic procession
- The Wild West, etc.
- They may be geological
- Pitchers want low ones
- Numbers for closers
- Periods, ages