Related Clues:

• Charlize Theron film, '-- Flux'
• Extremely long stretch
• Almost an eternity (Var.)
• Indefinitely long period
• Geologic span
• A billion years, in geology
• "___ Flux"
• A very, very long time (Var.)
• A billion years, to geologists
• Many generations
• Immeasurably long period of time (Var.)
• Umpteen millennia
• Mind-boggling time span
• Reeeeeeally long time
• Very long time (Var.)