Related Clues:

• Forever, figuratively
• Noteworthy period
• Time measured in ages
• Geologist's division
• Momentous era
• Astronomical unit
• Countless centuries
• Awfully long time
• Geologic period
• Unbelievably long time
• Mighty long time: Var.
• It goes on and on
• Noteworthy time
• Geologic time
• Date of reference