Related Clues:

• A very long time
• Time divisions
• It's a stretch
• Eternity
• Many eras
• Years and years and years and ...
• Near-eternity
• Lo-o-ong time
• Many, many years
• Geologic time division
• Amazingly long time
• An eternity
• Longish span
• Millennia
• Billion-year increments