Related Clues:

• So long
• Geologic time
• Cultural periods
• Vast sweep of time
• Longish time span
• Atomic and Ice, e.g.
• Time immemorial
• Kajillions of years
• Middle and Stone
• Periods
• L-o-n-g time period
• Thousands and thousands of years
• Wrinkles, say
• A really long time
• Long period