In order to illustrate the magnitude of the problem that he saw, Mormon illustrated with imagery from the world around him. He was illustrating that the story we have read demonstrated that God kept his word; if we are righteous, we will “prosper in the land;” and if we let pride get in the way, and harden our hearts, we will suffer, even eternally.
To accomplish his goal, Mormon contrasted the obedience of nature with the sinful disobedience of men. Unlike human tendencies, in response to the voice of the Lord, dust moves hither and thither, hills and mountains are transformed into valleys, and the whole earth shakes (see Helaman 12:7–12).
In response to this passage, Joseph Fielding Smith stated:
The point he is making is that the dust of the earth is obedient. … Everything in the universe obeys the law given unto it, so far as I know, except man. Everywhere you look you find law and order, the elements obeying the law given to them, true to their calling. But man rebels, and in this thing, man is less than the dust of the earth because he rejects the counsels of the Lord.
Joseph Fielding Smith in Official Report of the Ninety-Ninth Annual Conference of The Church of Jesus Christ of Latter-day Saints (Salt Lake City: The Church of Jesus Christ of Latter-day Saints, 1929), 55, quoted in K. Douglas Bassett, Latter-day Commentary on the Book of Mormon (American Fork, Utah: Covenant Communications, 1999), 386—Quoted in Grandy, “Why Things Move,”109, note 24).