Related Clues:

• Unratified proposal, briefly
• Geological time span
• Historical span
• Memorable era
• Amount of time
• History bit
• Portion of the past
• Pitcher's statistic
• Century 21 alternative
• Big Band __
• Themed period
• Disco ___
• The 50's, e.g.
• Failed amdt.
• Miocene, for one