Related Clues:

• Themed period
• Long time span
• Disco ___
• Long time, geologically
• It may be after lunch
• Long geological stretch
• A billion years, to Hubble
• The 50's, e.g.
• Failed amdt.
• Timeline time
• Progressive ___
• Important stretch
• Dog's age
• Eternity, seemingly
• Romantic or Victorian, e.g.