AM we worked in AC2 all morning before calling the day because of rain at 1 pm. We removed the last of Locus 7 from above locus 8, revealing a pit feature (locus 9) as well as a large round burnt feature (not yet designated, need to investigate, perhaps just a stain on Locus 8). Began drawing the stones of locus 8 so that the smaller ones could be removed. In digging down through the decayed concrete of this locus, we uncovered a large flat-lying ashlar in the north part of the trench underneath fallen ashlars and rubble. potentially an arch base?