This layer has not been excavated as of end of 2018 season. But it seems to represent a decisive horizon between the ashlar corridor phase and the creation of Rooms 4 and 5, with the construction of wall 7114/7115/7185 on top of this layer. See also 7257.
Layer of brown silt with frequent basalt inclusions in Room 5
Sketch of SUs 7221, 7234, 7242, 7257.
photo from north
photo from northeast
photo from east