The preparations already done for defense proved effective in the city of Noah. Moroni clearly understood that such defenses might be required in all locations, so he continued to prepare all Nephite cities. At this time, Mormon gives us more detail of how the defenses were created. Ridges, or heaps of earth, taken from ditches dug around their cities, are the same as the earlier description (see Alma 48:8), but here he specifically mentions that there would be a wooden wall built atop the ridges. Although it is possible that this is a new addition, it is also possible that Mormon only mentions it here, and that it was a feature of other fortifications.
One of the Mesoamerican sites that exhibits just this type of defensive wall is found in the site of Becán in the Yucatan peninsula. The site dates to Book of Mormon times, but might have been considered a Lamanite site rather than part of the Nephite hegemony. Nevertheless, this type of fortification appears in the correct time period and among cultures that could have been involved in the Book of Mormon story.