Here's why:

* Dozen years: Too short, barely a blink in geological terms.

* Thousand years: While longer, still relatively short compared to the vast spans of geological time.

* Hundred years: Even shorter than a thousand years.

* Million years: This is the scale at which significant geological events occur, like the formation of mountains, the extinction of dinosaurs, and the movement of continents.

Geologic time is measured in vast stretches of time, encompassing millions, tens of millions, even hundreds of millions of years.