This is most likely the cut of a foundation trench, filled by the remnants of a wall foundation (SU545). The layer through which it cuts has been overexcavated; the stratigraphic reliability is only fair. It is possible, although far less likely based on standard construction techniques, that foundation SU545 was placed directly on a clean bedrock surface and that the layer represents later accumulation; this interpretation would preclude the existence of this cut. But it is most likely that wall foundations SU545, SU541 and SU420 (vel sim.) were built inside foundation trenches that each cut.