If you don’t need an introduction to the debate over what the meaning of “head” is in reference to the River Sidon, you can skip down to the bottom of this post.
The Heartland Geographic Model for the Book of Mormon looks something like this:
As you can see, the “head” of the River Sidon is not a “head” at all, but rather a “confluence” of two rivers. At the Mormon Evidence Facebook group, Jake Hilton (who I’m almost certain is the administrator of the group), argues the following:
1828 Noah Webster’s Dictionary: “Head” – Definition #23 = “Conflux.” Look up the definition for “conflux” and you get “A flowing together; a meeting of two or more currents of a fluid.” It also says for you to see “confluence.” If you look up “confluence” in the same dictionary you get “A flowing together; the meeting or junction of two or more streams of water, or other fluid; also, the place of meeting; as the confluence of the Tigris and the Frat, or of the Ohio and Mississippi.” And there you have it. In 1828, as Joseph Smith was translating the record, the conflux of the Ohio and the Mississippi was regarded as a “head” of the river.
So, in order to get from “head” to “a meeting of two or more currents of a fluid” we have to use the 23rd definition, and then follow that definition across the dictionary.
Here is the word “head” in the 1828 dictionary: http://archive.org/stream/americandictiona01websrich#page/878/mode/2up
Here is the word “conflux” in the 1828 dictionary: http://archive.org/stream/americandictiona01websrich#page/446/mode/2up
There have been various arguments against this interpretation, starting with the fact that the river seems to flows from Manti through Zarahemla, and that Manti is south of Zarahemla and the text seems to indicate that Manti is higher in elevation than Zarahemla.
The “Head” of the River in Lehi’s Dream
However there is another bit of evidence in the Book of Mormon that I personally haven’t seen used yet, and which I think ought to be considered. 1 Nephi 8:13-14 says the following:
13 And as I cast my eyes round about, that perhaps I might discover my family also, I beheld a river of water; and it ran along, and it was near the tree of which I was partaking the fruit.
14 And I looked to behold from whence it came; and I saw the head thereof a little way off; and at the head thereof I beheld your mother Sariah, and Sam, and Nephi; and they stood as if they knew not whither they should go.
Here we have Lehi, in a vision, associating the “head” of the river with the place “from whence it came”. This is an obvious blow to the idea that the “head” of a river in the Book of Mormon is anything but its starting point.
I don’t want to overdo it though, because it isn’t the case that this one example of the use of “head” in reference to a river should dictate the way we interpret it in all other cases. The immediate and broader contexts of individual instances should be taken into account. However, we do know for a fact that in at least one case in the Book of Mormon the “head” of a river unambiguously refers to the place “from whence it came”. On the flip side, there are no examples anywhere in the Book of Mormon where the “head” of a river unambiguously refers to a “confluence”.