alternator problems

Ok, so I went out out 4wheeling with my friend last week, and found some mud holes and what not, you know the usually stuff. The alternator on my jeep is still pretty new, an di have a brand new battery. The same day we went out i was at the gas station and it didn't want to start. When I checked the battery, it was a little bit dirty. I cleaned the terminals, and it fired right up. As i was driving down the road my radio cut out, and I suddenly lost power. When i pulled over it would still idle, but when i gave it gas it would almost stall out. After I turned it off and tried to turn it back on it would just click. So I had a friend give me jump to get back home, it died 3 more times within a 12 mile distance, so I narrowed it down to the alternator. I have heard that jeep alternators don't really like getting dirty, but it just doesn't sound right to me. Like I said the alternator is still fairly new. Any suggestions, comments, or feedback is appreciated.