Both are divided into three subunits. Interpretations of the lithostratigraphy are hampered by uncertainties regarding stratigraphic ages.
Lithologies consist of hemipelagic mud, sandy mud, and volcanic ash.
I have been subjected to significant amounts of displacement along either a submarine slide surface or a folded thrust fault. Below the dislocation surface, more highly deformed strata are almost certainly part of the Nankai accretionary prism. Similarities are striking between their lithofacies associations and those of the axial trench-wedge environment. This repetition of facies confirms the occurrence of one of the imbricate thrust faults within the accretionary prism. Structurally, Site 1178 consists of four domains.