Related Clues:
- Proterozoic, for one
- Vast time unit
- Largest division of geologic time
- One billion years (Var.)
- Long stretch of history
- Centuries on end
- Long time, even in the singular
- Quite a span
- Nearly an eternity
- An immense time
- An immense period of time
- A very long time, an age
- Very long and indefinite period of time
- With this could one get Russell on time for long?
- Is Russell on time?