This is a layer of floor prep that is only visible in small sections below another, later layer of floor prep (6121). Both SU 6122 and 6121 appear to be of a similar construction type with consistent use of a similar white mortar. This floor prep layer may be the second oldest chronologically still preserved (with SUs 6161, 6217, and 6167 possible representing parts of the earliest surface made of various stones and cut tufo blocks). SU 6122 likely once extended to cover the entirety of room G-1.