According to Alvin Benson, if volcanic eruptions lasted for several hours, as indicated in 3 Nephi 8, an enormous amount of ash would have been discharged into the atmosphere. The ash from a volcano can rise to great heights (many thousands of feet) and then spread out in the stratosphere to cover a large region with an impenetrable cloud of dust (Goldner and Vogel 37-43; Warren and Ferguson 42). Volcanic ash, smoke, and gases, along with dust and debris rising into the air from a large earthquake, could have produced the "vapor of darkness" spoken of in 3 Nephi 8:20 and 10:13. [Alvin K. Benson, "Geological Upheaval and Darkness in 3 Nephi 8-10," in The Book of Mormon: 3 Nephi 9-30, This Is My Gospel, p. 64]