Extremely compact brown layer with granular tufo inclusions. Located near to east side of SU 4039/4040, north-south road retaining wall and near to south side of possible road (tufo paving stones) 4041. Found beneath accumulation layer 4031 and on top of two other amall layers, one loose, light gray layer to the east (4045) next to circular feature and to the west is the typical yellowish layer (fairly small). Exact purpose unknown, could be geological or anthropic as it in not similar to any of the surrounding layers or features. Deposition could be result of anthropic activity. Does not appear to be natural accumulation, but could be.