When Moroni says, "I will write and hide up the records in the earth; and whither I go it mattereth not" (Mormon 8:4), does Moroni intend to hide up the records in the earth before or after he goes where "it mattereth not"? Or is he referring to a process? Immediately after this verse, in Mormon 8:6, Moroni mentions that "400 years have passed away since the coming of our Lord." Thus, considering the fact that the Book of Mormon plates at this time were still lacking the book of Ether and the book of Moroni, we might say that not only were the plates not ready to be hid up permanently yet, but Moroni still had quite a bit of translation work yet to do. The reader should note that Moroni makes no mention of hiding up his records in the hill Cumorah, but rather in "the earth." [Alan C. Miner, Personal Notes]
Mormon 8:4 I will write and hide up the records in the earth ([Illustration]): Stone Box from Chichen Itza. Here is one example of an American stone box dating to A.D. 650-900. Discovered at the base of the temple of Kulkulcan at Chichen Itza in Yucatan, Mexico, in the late 1800s, where it is exhibited, it measures approximately 2.5 by 2 by 2 feet, exterior. The box is carved out of one piece of stone, the rounded lid out of another. In this box were found masonry tools; other stone boxes containing jewelry and precious textiles have been found throughout Mexico and Central America. Many of them are on exhibit in the Museum of Anthropology, Mexico City. (See Cheesman, "The Stone Box," Improvement Era, Oct. 1966, pp. 876-78, 900) [Paul Cheesman, "Ancient Writing on Metal Plates," The Ensign, October 1979, p. 47]
“Therefore I Will Write and Hide Up the Records in the Earth”
David Whitmer, in an interview with P. Wilhelm Poulson in 1878, said, "I saw the place where the plates were found, and a great many did so, and it awakened an excitement at the time . . . Poulson asked, "How did the place look?" Whitmer replied, "It was a stone box, and the stones looked to me as if they were cemented together. That was on the side of the hill, and a little down from the top." 
According to John Tvedtnes, the plates from which the Book of Mormon was translated were not the first sacred text known to have been kept in a box. A large number of documents and archaeological discoveries confirm the antiquity of the practice, which predated Moroni by centuries. Records were kept in arks and foundation stones, as well as in boxes made of stone, metal, and earthenware.
According to Hebrews 9:4, the ark of the covenant constructed in Moses' day held "the golden pot that had manna, and Aaron's rod that budded, and the tables of the covenant." That the tables of the law were kept in the ark is confirmed in Deuteronomy 10:1-5 and 1 Kings 8:9 (= 2 Chronicles 5:10). The ark evidently held other records as well, for we read in Deuteronomy 31;26 that the Lord told Moses, "Take this book of the law, and put it in the side of the ark of the covenant of the Lord your God, that it may be there for a witness against thee." In the introduction to his Mishneh Torah, the twelfth century Jewish rabbi Maimonides commented on Deuteronomy 31:26. He noted that Moses had inscribed thirteen copies of the Pentateuch, then delivered one to each of the twelve tribes of Israel and placed the master copy in the ark. Petirat Mosheh, recounting the same story, notes that the angel Gabriel took this thirteenth scroll and brought it to the heavenly court.
To this day, Jews and Samaritans alike keep the scroll of the Torah (law) of Moses in a cabinet known as an ark. It is typically covered with a small curtain representing the veil that separated the holy of holies of the ancient temple or tabernacle (where the original ark of the covenant was kept) from the rest of the sanctuary. While some of this symbolism is not present in Joseph Smith's account of the hiding place of the plates, the stone box in which they were deposited clearly served the same purpose as the ark in Moses's day. The two receptacles are also alike in that in addition to the records, each contained other sacred artifacts. [John Tvedtnes, The Book of Mormon and Other Hidden Books: Out of Darkness unto Light, pp. 33-33, 35]
Moroni 10:2 I seal up these records (stone boxes) [[Illustration]]: Many Ancient Cultures Have Buried Records in Stone Boxes. Old World Records: Engraved plates of gold and silver were found buried in a stone box in the ruins of Persepolis, the ancient capital of Persia dating from the same century in which Lehi left Jerusalem. [Glenn A. Scott, Voices from the Dust, p. 230]