This is the end of the small plates of Nephi. This was the Lord's great backup plan—to preserve the small plates in case someone named Martin Harris should lose the 116 pages translated from the large plates. This story is one of the greatest examples of the foreknowledge of God and his great wisdom in preparing for the foibles of man.
'I will not suffer that they shall destroy my work; yea, I will show unto them that my wisdom is greater than the cunning of the devil…
Behold, there are many things engraven upon the plates of Nephi which do throw greater views upon my gospel; therefore, it is wisdom in me that you should translate this first part of the engravings of Nephi, and send forth in this work.' (DC 10:43,45)