Quaternary sediments are apparently more widespread and better represented in the northern Scott Plateau and Java Trench than in parts of the central Scott Plateau, where older rocks are exposed on the sea floor. Nevertheless, wherever Quaternary calcareous nannofossils are recovered from these areas, they are associated with reworked Upper Cretaceous and Tertiary forms. This may have been caused by bottom currents actively eroding parts of the central Scott Plateau and redistributing the fine fraction elsewhere on the plateau, Java Trench and nearby areas. These currents may have been active from the middle Miocene. Late Pleistocene to Holocene calcareous nannofossils occur throughout the near-surface (ca 1 m thick) sediments in the northern Scott Plateau, but are absent from such sediments in the Java Trench. However, Pleistocene nannofossil assemblages, older than those from the Scott Plateau, occur intermittently at lower levels in the near-surface (ca 1 m thick) sediments in the Java Trench. This difference is explained by suggesting that the present Nanno Solution Depth lies between 3290 m and 4950 m water depth in the Scott Plateau and Java Trench areas, but in earlier Quaternary times it fluctuated between 5090 m and 5424 m in the same areas.