Here's a breakdown of the major divisions from longest to shortest:
* Eon: The largest division of geologic time, representing hundreds of millions or even billions of years.
* Era: A subdivision of an eon, often lasting hundreds of millions of years.
* Period: A subdivision of an era, typically lasting tens of millions of years.
* Epoch: A subdivision of a period, lasting a few million years or less.
Let me know if you'd like to know more about any of these divisions!
