Hii!
Interest doesn't see anything else. If you feel good and excited and curious reading a subject, that shows your interest. Same is with geology. And to study a course, practically you need to look at the eligibility criteria. The eligibility criteria for BSC geology states that the candidate must have passed class 12th with minimum 50% marks in science stream from a recognised board of education. If you satisfy this criteria, you can study the course.
Hope this helps.
Good luck !