This morning we took levels in AC3 for loci 2 and 6, then removed the pedestaled rocks, closed those loci, and started taking down a unified locus (locus 8) of gritty fill occupying the entire trench between the wall (locus 4) and the arch base (locus 7). towards the end of the morning we uncovered a ledge of ashlars beneath the wall on the west side of the trench.
troweled out locus 4 in AC4, and started taking down locus 5, which is silty and light brown and has a pretty high material density.