Related Clues:

• Unit of time (Var.)
• ''___ Flux'' (Charlize Theron film)
• At least two of 22-Down
• Very long period of time
• Long, long time (var.)
• Another way to spell 57-Across
• Another spelling for 14-Across
• A dog's age?
• One billion years equal one
• Simpler spelling of 34-Down
• Many millennia (var.)
• Many a year (var.)
• Largest division of time, in geology
• One spelling for one billion years
• Very, very long time, in geology