What is the correct order of geological time scales from largest to smallest?

This hierarchy comprises eons, eras, periods, epochs, and ages from the largest to the smallest

Explanation:

This hierarchy comprises eons, eras, periods, epochs, and ages from the largest to the smallest. All of these are shown in the geological time scale page.

Eon                      Era          Period            Epoch           Age

PhanerozoicCenozoicPaleogeneOligoceneChattian  Rupelian

The Phanerozoic Eon reflects the period that most macroscopic species — bacteria, fungi, plants, and animals — lived through.