Chronological detail in the Book of Mormon

It is interesting to note that the portions of the books of Mosiah and Alma detailing events that took place in Lamanite territory (Mosiah 9-24 and Alma 17-27) have far fewer chronological markers than the portions of these book which take place in Nephite lands. It seems as if the sources had a different level of attention to this detail, which is evident even in Mormon's abridgment.

I read this assertion about the chronological markers not being found in long stretches of the story that takes place in the land of Nephi and (as usual) I wanted to see it for myself. So I made a chart of the number of chronological markers in each chapter of Mosiah and Alma.

This was a really interesting exercise.  What I found was that in chapters where Mormon is abridging Nephite history (presumably working from detailed Nephite records), there are many chronological markers (up to 12 in Alma 63 alone). Whenever possible, it seems, Mormon likes to give these markers as bookends in his narrative, documenting the beginning and the end of the year in many instances. In other chapters, when we are reading the direct words of others, particularly in sermons and some epistles, we get no chronological markers at all.

I made a graph.

In some ways, this is completely obvious and expected--the "historical record" part of the text is replete with chronological indicators and the other parts are not.

What is interesting to me is how intricate and complicated the narrative is.  Let me give a few examples that stood out while I undertook this exercise:

1. Alma 47 (0 chronological markers) begins with the words: "Now we will return in our record to Amalickiah and those who had fled with him into the wilderness..." We then get a pretty detailed account of the inner workings of "the bad guys." What source is Mormon using here?
2. Whenever possible, Mormon gives us exact dates.  We get to know the exact date Moroni received the epistle from Helaman (30th year, 1st month, 2nd day).  This must have been recorded somewhere for Mormon to have knowledge of it hundreds of years later. Helaman's epistle goes on for three chapters (Alma 56-58), and contains several chronological markers, all of which refer to the 4 years prior to the 30th year.  So we get a small flashback contained in the bigger narrative. 
3. The same thing happens on a bigger scale when the sons of Mosiah meet Alma-2 in the 14th year and we then get 11 chapters detailing their missionary labors (kept by someone who apparently didn't include many dates.)
4. The result of skimming the 92 chapters of these two books in one sitting specifically for this purpose highlights how many different voices Joseph Smith would have had to keep track of, had he been authoring the book spontaneously, as some believe he did: King Benjamin, Mosiah-2, Zeniff, Abinadi, Alma-2, Amulek, Ammon, Lamoni, Lamoni's father, Helaman, Moroni-1, Pahoran, etc.  Not to mention Mormon's editorial comments laced throughout and in between.  It's a complicated arrangment.

Of course, this is not a very hard task for any author to accomplish, if they are given the time and the ability to take notes. Making the argument that Mormon had the time, education, and means to carry out this task is easy. Joseph Smith had neither time nor notes from which to work, and the work was completed in a single draft. It's remarkable.

Hat tip: Grant Hardy.