Related Clues:
- So long!
- A kazillion years, it seems
- Millions of lifetimes
- Great geological time span
- Geological age
- Quasi-opposite of ''flash''
- Tremendous spans
- Proterozoic ___
- Ages upon ages of time
- Geology class periods [subscribe to the best indie xwords today at avxwords.com]
- See 19 across
- A lot of the time?
- Eras upon eras
- Geologist's unit
- Many, many epochs