Related Clues:
- Geologist's ten
- Meaningful spans
- Aces have low ones, briefly
- Often-named stretches
- Historic blocks
- Common and Christian
- Stretches in history
- Significant chunks of time
- Gaslight and Big Band, for two
- Stats for hurlers
- Periods of historical time
- Notable parts of history
- Eon divisions, in geology
- Many are named for presidents
- Pitching staff stats