Geology comes through scientific Latin geologia. Its components name the earth and a study or account. Rocks supply evidence for that study, but the first component means earth rather than simply stone.
This view explains the components. They are pieces of one construction, not consecutive borrowing stages.
Sources
- Merriam-Webster · geology
Formation of the word.
- Merriam-Webster · geo-
Meaning and history of this component.
- Merriam-Webster · -logy
Meaning and history of this component.