Alteration to limonite locally occurs. The biogenic components increase to their peak value. Ash and pumice are rare throughout the unit. Brittle deformational structures occur first and reach their peak within this unit. Minor lithologies only occur rarely.
Minor lithologies are rare.
Calcareous nannofossils are generally barren to abundant throughout, with variable preservation. As at Site 1150, of the 11 nannofossil datums identified, seven gave ages younger than those indicated by the diatom datums. Except for some ash layers and dolomite layers, the sequence contains few to abundant diatoms throughout. Diatom assemblages from all samples consist almost entirely of oceanic species, mainly from the subarctic North Pacific Ocean. Sedimentation rates at Site 1151 were estimated using a combination of biostratigraphy and magnetostratigraphy.