This is driving me crazy: how did the geologist in Prometheus get lost? He has advanced mapping technology (the flying robots), is an expert on caves, and the spaceship has real-time tracking technology, as evidenced by the fact the captain is able to tell him he saw "something moving" near him (what he later calls "a glitch"). They are also in constant communication with the ship (at least until the storm, I can't remember if it affected comms). In those conditions, it seems it would be impossible for anyone to get lost, let alone an expert.
The guy does seem a bit distressed when they find the alien corpses and artifacts, just before he decides to go back to the ship, but really -- an alien-finding expedition finds aliens. Is that the reason he freaked out and forgot everything he knew about caves?
Is there any in-universe explanation? Was the geologist simply a loose cannon and a lousy expert?