This is a sum and part situation. Geography is the study of the earth and the atmosphere and how they react to the various things living on the surface. Geology is the study of the earth’s physical structure, the history, and the different processes that act on the earth (such as desertification, erosion, and weathering).
In this respect, geography is the whole, and geology is the part. While one can study both, studying geology is to study a more specific area of geography. However, there are other specific areas of geography that can be studied. Even geology has more specialized areas.
Which one you study all depends on what you like. Take some basic courses in both of the areas and go from there.