Genesis 29:2. Out of that well they watered the flocks: and a great stone was upon the well’s mouth.
This was to protect the water from impurity, and from shifting sands, which without such protection would soon choke it. Modern travelers make frequent mention of the stone covers to wells and cisterns. Some of these stones are so large and heavy as to require the united strength of several men to remove them. May there not be reference to this custom in Job 38:30: “The waters are hid as with a stone, and the face of the deep is frozen.”