According to Rabbi Akiva, the passage in Sefer Bamidbar (19:16) “And whosoever in the open field toucheth…” – which is taught in the context of the laws relating to ritual defilement and the dead – comes to include the case of someone who comes into contact with a gollel and dofek, teaching that such a person will become ritually defiled.
The commentaries disagree about how to define these terms. Many commentaries, including Rashi, explain that the gollelis the cover to a casket, while the dofek are the walls of the casket, upon which the gollel rests. This appears to be the position of the Rambam, as well, who explains (Mishneh Torah, Hilkhot Oholot 2:4) that the walls of the casket are called the dofek because they press down – dohakim – on the dead body. Rabbenu Tam argues that our Gemara clearly relates to these things as being above ground, “in the open field,” so they cannot possibly be part of the casket. He suggests that these terms relate to the tombstone that is aboveground, with the gollel as the large stone placed above the grave (apparently horizontally), while the dofek refers to the stones upon which the gollel lies – pressing down on them.
These explanations clearly relate to the burial practices that were common in the Medieval period. During Mishnaic times, burial traditions in Israel often included interring the corpse in a burial cave that served as a temporary grave where it would decompose. At a later date, the bones would be removed and transferred to a family burial cave. This cave was sealed by means of a “rolling stone” – a gollel – which was held in place with another stone – a dofek. In some cases, wax or clay with the impression of the owner’s seal was placed between the stone and the wall so that it could be easily determined if the tomb had been opened. To enable people to descend into the large tomb, the dofek was pried loose and the gollel was rolled away.