Crossword Genius

Geological periods (4)

Ross

I think it could be either:

eons

eras

'geological periods' is the definition.
(I've seen this in another clue)

This is all the clue.

(Other definitions for eons that I've seen before include "Divisions of archaeological time" , "Years and years" , "Nose (anag)" , "Divisions of geological time" , "Very long periods (US)" .)

I've seen this clue in the Universal and the Canadiana.
Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.