Related Clues:

• Time measured in ages
• Geologist's division
• Years upon years
• Astronomical unit
• Countless centuries
• Long periods of time
• Awfully long time
• Geologic period
• Geological periods
• Unbelievably long time
• Mighty long time: Var.
• It goes on and on
• Geologic time
• Vast sweep of time
• Longish time span