Given you don't expect a high-flying career, then paying for a brand-name degree is not necessary. Were I you, I would focus on finding the lowest-cost way to attain an accredited Geology qualification, rather than on just taking the first pathway on offer and working out how to smash the debt later. I am unfamiliar with US higher education, but "community college" sounds like a good place to start looking.
Remember, a dollar not spent is a dollar saved (more, actually, because it frees you from the extra cost of interest) - it is better to avoid taking on debt in the first place than to have to deal with it after.
Another option is to work part-time and study part-time. There is no shame in doing this - in fact, I think it is a more intelligent way to go. You'll have to make and keep a budget, and MMM's articles should be able to get you started. Once you have one, you can post it for feedback... I'm not sure exactly where. Journals?