shulem, when reading your first comments about this river Laman I had no memory of it. All you hear about the journey is crossing eastward to Nahom. I decided to hunt up the matter it sounding a bit odd and the crossing mentioned is what I first found. I later found the earlier mention you were thinking of.
If my stumbled upon mention is a help you are welcome. My search reminded me that I am uncomfortable with a variety of things in the story. Bow and arrow all that game in the desert? Oh well I cannot be certain that that could not happen even if it sounds like the details of a youthful storyteller with more energy than experience.
A well educated storyteller would be unable to imitate youthful amateur this well.
Now I can imagine a supporter of the book proposing that the effect is a result of the retelling of the story by Mormon and or Moroni.