After further study and identification of this area as a quarry, it appears that this is one of a series of cuts into the bedrock associated with quarry machinery. This one, specifically, may have accommodated one of the posts to which cranes’ tie-rods were tied

Possible posthole for a large post. More possibly a receptacle for dolia because we have pottery & bone in the fill material. This may be a hole for a dolium for either domestic or mortuary purposes.