ST1: Taking the extension of the trench down to the same level as the base of the original trench, before continuing down with the whole thing as one locus. Rather optimistically brought the screen out, but probably won't use it today.
As we took the trench down, came down on a slightly more compact, more mottled level, may or may not be the floor. Clearing to this level to be continued as another locus. Still not clear about what is going on with the jumble of small rocks in the sw, whether they constitute part of the wall, or whether they're tumble.