The natural geological layer into which the foundation was built; found also in 15000 and 16000. Cannot find foundation cut for Opus Reticulatum walls; wall built through chocolate, 17100 and into natural 17101

The chocolate layer found in 10000, 14000, 15000, 16000. Wall 17018 an 17020 built into chocolate layer; covers a gritty yellow natural layer. Very homogenous silty soil. Rich brown with no materials