7/1/13 It became ever more apparent today that WSDB is, for the most part, a passageway of some sort, running diagonally from WSDA to...not sure where. It is marked by two parallel alignments of stones separated by approximately a meter and a half (narrower to the southeast, widening to the northwest). What is most peculiar, however, is that the northeasterly alignment seems to stop abruptly, and it is this that suggests it may possibly be an internal divider. Yet it is quite high in the stratigraphic column to resemble the internal dividers encountered in Precinct A. Fortunately, as we have now exposed two courses of these walls, one stone of which is plastered, I suspect we are not too far from the floor. Indeed, will start screening tomorrow, and then perhaps expand the trench in the coming days. Will consult with Elizabeth Fagan about the expansion.