Layer of post-abandonment accumulation filling cut SU555. However, based on the close-packed large roof tile fragments that filled the south half of the cut through the whole depth of the layer (and large unworked basalt stones in the very south part of the cut with more tiles underneath), this may be an intentional deposition (discard? to block the channel?). Alternatively, this may be a collapse (of some sort of covering of the channel or of a nearby as-yet-unidentified structure). The situation in cut SU555 with the tiles and basalt at the south end (SU554) is analogous to the fills of cut SU510 (SU532 = tile-rich fill at west end; SU535 and SU539 = packing of mostly basalt stones at east end of SU510), suggesting that the cuts SU510 and SU555, which are two separately numbered sections of the same cut, were filled in the same manner and likely at the same time.

After study, it appears that this was one a series of fills of a drainage channel in the area.