If my whole life wasn't depending on it, my personal statement would look something like this (keep in mind, they all pretty much ask the same thing...but they want it in essay form):
1. Future plans in geology: Hike around in the desert and mountains (ie, the American West) and come up with interesting theories as to why they are the way they are. Oh, and never work behind a desk unless it comes with a professor-ship at a neat school. And is made of some sort of dark wood. And it sits in a room full of books, geologic and otherwise. And I teach young, eager minds. Either or is fine by me. Otherwise I'm not going to work ever.
2. Why you want to pursue a Masters Degree(at this school): So that I can do the above, plus your school is located in a small town close to my home surrounded by sweet geology.
3. What specifically you would like to research: Structure...I like mountains.
4. Overall preparation to enter your chosen field: Probably not quite enough but brimming with enthusiasm!
5. Special interests: Being outside and good food...are we done yet?
Alas, tis not. And all the time I've wasted on the internet in the past hour or so probably would have been better spent phrasing the above in a very poetic, appealing, and much more serious way. Unfortunately, I lack productivity at the moment...