I could be crazy but I thought the beam of light that fell on balins tomb came from a shaft that went 100's of metres through the mountain and exited near the top of the mountain somewhere. Much like the shafts they have found in the Eygyptian pyramids.
That is the logical place for it to come from. In fact, I think it did. In the movie, when the Fellowship exits the tomb, the shaft of light showed on the tomb through a hole in the wall. I think it continued down the great chamber too.
Edited by MirkwoodArcher, 07 November 2009 - 03:06 AM.