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

This hole is most likely not a garbage pit because of the relative lack of material culture in the layers. It may be a posthole for a large post or it may be a cut to hold a dolium.