Related Clues:
- Important historic period
- Geological time period
- Important time span
- Archeozoic, e.g.
- Depression, for one
- 1970's-80's cause, for short
- Perfect start?
- Gay 90's, e.g.
- History text topic
- It may have periods
- Feminist pitcher's concern?
- Historian's interest
- Geological time
- Geologist's time division
- Oft-nicknamed period