When I was in college, I quickly found that I really liked environmental geology - dirt and groundwater. At the same time, I didn't have a whole lot of other options. Here was what I could do for a career in geology:
1. Teach. This post explains why this was a non-starter from the beginning.
2. Resource exploration: generally, mining/oil.
3. Environmental stuff.
Am I missing anything? I don't really think so. I could have fallen in love with some corner of geology and gone on in research, but I was insecure in my brains/geological abilities and I didn't think I was cut out for it. Now that I'm older, my self-confidence is a lot higher, but I'm fairly happy with my career path. Also, I detest teaching.
#2 was out for a simple reason. I am an east coast city girl at heart, much in the way I will always be a geologist at heart. There's not a whole lot of mines or oil fields close to east coast big cities. The last thing I wanted was to be living in Texas or Alberta or Colorado or Dubai for the forseeable future.
I haven't mentioned some marquee jobs like working for the USGS in some cool researchy capacity, because they require lots of experience or there's lots of competition for them. My low self confidence and utter lack of experience when I graduated effectively eliminated those.
So, did I fall into environmental work because I loved it so, or was I pushed because I didn't see other options? Well, a little bit of both. If I could have had a viable career right off the bat involving plate tectonics or certain aspects of petrology, maybe I would have gone in that direction. But I do enjoy working in the field, doing science-y stuff, and I'm hoping that my masters degree will point me toward cooler and more scientific work in the discipline that I'm focusing on. That is, if I get this friggin degree! Back to work...