When I was a senior in college, I took a course in geology., I loved it so much that I would have chosen the field for a major had I been exposed as a freshmen or sophomore. But, as a senior, I had already pursued a different major. It is important to be exposed to as many areas of human activity as possible, as soon as one is capable of appreciating it.
Travel. An interest like geology can provide a vast number of objectives of interest to justify journeys, while giving them purpose and objectives, but when once you are on the journey, then it is what you find beside the road which you did not go looking for, which adds huge amounts to the richness and wonder of life.
You can still go forward with geology or any other area you want to explore. Hard to make a living in geology though. You could teach (rewarding) or get a job with an oil company (yuk).