After pondering a little, James decides that the darkness is not coming from some kind of monster. It wiuld be prudent to probe it a little, although entering it wont be a very bad idea either...
@Todd:
SpoilerYou can tell that the darkness has a magical aura.Make a concentration check to learn more...You can also tell it is some kind of force field...it would be prudent to probe it first...but somehow you feel that it wont hurt you if you pass through.