The two main things we did today were continue troweling in locus 20 and lay out a new 3 by 3 m trench in WSM. The situation in locus 20 is confusing. A packed yellow clay is emerging along the NE then seems to peter out towards the center unless it dips lower than we are. Confusion about the situation with these walls. Looks like rocks are resting only on the brown clay. Carbon specks found in locus 20 and one was collected. Altough the security of the NE wall is tenuous, I'm continuing down here because there are still a lot of materials.