According to Ben Olsen, who has some geological experience in Mexico, Guatemala and Belize, it is interesting to note that the Book of Mormon records several instances of people being thrown into "pits" (Ether 9:29). In many humid areas, where limestones are exposed at the surface, such as the Yucatan Peninsula and Florida, sink-holes are common. These collapsed areas, where water has weakened the structural integrity of the strata and allowed the surface layers to cave in, form what is called karst topography. Could these sink-holes or cenotes (such as occur at Chichen Itza) be the type of "pits" referred to? [Ben L. Olsen, Some Earthly Treasures of the Book of Mormon, pp. 55-56, Unpublished]