Related Clues:

• Geologist's measure
• Hoped-for low number: Abbr.
• Turn color, maybe
• Memorable period
• Time on end
• Many, many moons
• Unit of Time
• Be overly fond
• Special time
• Historic period
• Pamper, with 'on'
• Grow up
• Chapter in history
• Fully developed
• Billion years, to a geologist