adobe bricks
Each group of dark gray rectangles represents one load of adobe bricks that had to be provided in tributes (for construction). So this detail shows two loads. We do not know how many bricks there were in a load, but the stack on our left appearing here shows 22 bricks (at least on the face of the stack that is toward the viewer) and the stack on the right shows 18 bricks (on the face of the stack). [SW]