Related Clues:
- Quite a long time
- It's longer than an era
- Big time division
- How long it takes canyons to form
- Span of epoch proportions?
- Ages and ages and ages
- Extensive period
- Immeasurable time
- Billion-year time period
- One billion years, geologically
- Humongous span
- Annoying wait, facetiously
- A seeming eternity
- Untold eras
- Inconceivable stretch