Started workers today bringing down the level of Locus 4 (northern corner) to the closing level of Locus 3 in the rest of the trench, and then had Aparani Artur trowel the stones there. It seems like two faces of the NW wall are now visible, with the interior face (facing the room) made of smaller stones. There is still a very yellowish, almost chalkish soil around these stones within the wall but not on the other side of them.
I then opened up three new loci in the rest of the operation. Locus 5 constitutes the emerging lighter brown, more compact soil that currently extends from the northern corner along the NE baulk and down the SE baulk, delimited by several large stones about a meter from the NE baulk. To the SW of this locus is Locus 6, covering most of the trench and the southern and western corners and along the wheelbarrow ramp, as well as the linear feature of stones with one huge one in the center running parallel to the NW wall. The matrix is the darker, looser soil similar to Locus 3 above. Locus 7 is a pocket of soil similar to locus 5 along the SW wall where the elevation is only about 25 cm higher than the floor discovered in WSAC2. There are a lot of large stones in the SW part of the room which are only barely iceberging now.
I started the guys excavating Locus 5, which took most of the day, as well as picking up all of the dirt that had fallen off of the SE baulk into WSAC2 (this material I added to Locus 5). Locus 5 ended up being more of a mixture of the darker looser soil and the browner compact soil, and we came down on a number of rocks in the northern area. The guys cleaned the surface of this locus; no small finds. After lunch I had them start one shovel pass in Locus 6, and they worked in the area between the NW wall and the linear feature of stones, to the wheelbarrow ramp, where the soil is very dark. The linear feature of stones is now obvious, with the very large rock which is about 2.5 m from the NE baulk sitting on another emerging rock, suggesting another course. I'm concerned that we noticed this too late and some smaller stones were removed during shoveling without us realizing their placement. At the end of the day I had the guys dig around several stones that appear to form a line running N-E at a right angle to the one running W-N, and I'm not sure at this point if I have something similar to what Jake has found in his trench in a rectilinear feature of stones. Interior partition wall?