Dark, silty deposit overlying bedrock and sections of wall 1184. It appears to naturally abut SU 1386 which is separated by an irregular rubble fall along the southern edge of 1423. Presumably 1423 represents a natural deposition prior to the deposition of SU 1386 to the south. 1423 may be contemporary to SU 1428 to the west, but appears distinct based on soil composition.