Here's why:

* Geo comes from the Greek word "γη" (ge), meaning "earth."

* -logy is a suffix commonly used in English to indicate a field of study or knowledge.

So, "geology" literally means the "study of Earth."

However, it's important to note that "study of Earth" can encompass many other disciplines besides geology. It could also refer to:

* Geography: The study of Earth's physical features, human populations, and the interactions between them.

* Environmental science: The study of how humans interact with the environment and the consequences of these interactions.

* Oceanography: The study of the oceans.

* Meteorology: The study of the atmosphere and weather.

* Climatology: The study of climate.

So, while "geology" is the most literal interpretation, "study of Earth" can have a broader meaning depending on the context.