Related Clues:

• Long period of time
• A month of Sundays
• Prolonged period
• L-o-n-g stretch of time
• Looooong time
• Notable time period
• Many millennia (Var.)
• Extremely long time period
• Geological era
• Big stretch
• Time without end
• Quite a long stretch
• Wait at the motor vehicle bureau, say
• It's a big stretch
• Long geological time