38-51 in. Interval: very oily silt. Consistency is like stiff dough. The dark gray to blue layered zone contains much oil contaminated with PCBs. This zone was later the main target of remedial dredging.
51-65 in. Interval: oily silt over sand. Just below the remainder of oily silt begins a layer of clean sand with occasional gravel. This is native material representing the original river bottom.
65-78 in. Interval: sand over gravel. The coarse sand merges into a gravel layer, also uncontaminated.