As another geology major, I agree with Vene: leave the job, and take the offer. Google's temporary anyway, right? Getting into grad school will give you incredible opportunities, especially in geology...you could find yourself teaching field school, traveling to new places for your dissertation work. You will have the next 4 to 5 years figured out. And when you're done, you'll probably be able to find a job making much more than you make now as a BSc.
The other problem is, once you've completed your job at Google (if you decide to keep working there), you'll have to reapply to grad school. The last thing I would want to do is go through the whole debacle again, but while that's a personal preference...think about this. If you decide to reapply to schools at the end of your run at Google, you may not get into any programs because of funding issues, or not enough room in the department, or whatever it may be at that time. Besides, if you like your job this much, you can always return to Google after you've completed your PhD. Grad school is hard to get into, so take it while you have it! And really, you won't regret it (especially in this field; it just gets better).