Reference: While this description certainly fits the aftermath of a large earthquake, it was probably influenced by Joseph Smith’s familiarity with Luke 3:4–5:
As it is written in the book of the words of Esaias the prophet, saying, The voice of one crying in the wilderness, Prepare ye the way of the Lord, make his paths straight.
Every valley shall be filled, and every mountain and hill shall be brought low; and the crooked shall be made straight, and the rough ways shall be made smooth.
The rough/smooth pairing is a conspicuous allusion. Luke is paraphrasing Isaiah 40:3–4:
The voice of him that crieth in the wilderness, Prepare ye the way of the Lord, make straight in the desert a highway for our God.
Every valley shall be exalted, and every mountain and hill shall be made low: and the crooked shall be made straight, and the rough places plain.
Isaiah does not pair “rough” and “smooth.” Therefore, the connection between the Book of Mormon and the biblical texts is to Luke. However, because the Isaiah passage would have appeared on the brass plates, Nephi may have alluded to it as a reminder that this sign had been prophesied as part of the Messiah’s advent.