Moroni refers to an incident in the history of the Jaredites, not recorded elsewhere. The Brother of Jared said to Mount Zerin, Remove! and it was removed. Where and how this happened we do not know. But it is, by no means improbable, that the Jaredites during their migrations from the coast to the interior of the Continent of Asia, encountered some mountainous obstacle which the Lord removed in answer to the prayers of faith of the great Jaredite Moses. It may have been done by some physical adjustment of the earth such as an earthquake, or by some supernatural agency unknown to us. Whatever it was, be it either case, it was a miracle, a divine reward of Faith.