Related Clues:
- Mammoth time units
- Inordinately long time
- About 525 trillion minutes, in astronomy
- Uncountable years
- Astronomical time span
- Umpteen years
- Forever, more or less
- Nigh-infinite periods
- Vast time span
- Extremely long time periods
- Many lifetimes
- 365 billion days, geologically
- Big stretch?
- Geologic stretches
- Long geological span