This linear feature is one of the key indications of the original arrangement of the southern end of Room 16. It seems likely that it was the foundation preparation for an E-W ashlar wall that would have bounded the Room paved by 5662 at the south.

Not excavated in 2014. Layer was probably a sort of preparation feature for the drainage features south of it to rest on (5739, 5586, 5595, 5665) as well for an E-W wall that would have run along the north side of 5586, 5595, and 5739. It was made of packed dirt (high clay %) on top of bedrock, so it was probably a solid and stable foundation.