The nannofossil biostratigraphy presented here is based on examination of smear slides prepared from unprocessed sediment. Slides were examined using phase-contrast and cross-polarized light at 1560x on a Zeiss Photo III light microscope. The relative abundance of each species, general preservation of the assemblage, overall abundance of nannofossils, and presence of reworked nannofossils were recorded. Abundance of individual taxa, as well as overall abundance, are represented by letter codes and are recorded in Tables T1, T2, T3, and T4 according to the following definitions:
Preservation of nannofossils can vary significantly because of etching, dissolution, or calcite overgrowth. As the finding of well-preserved specimens in the same sample as overgrown or etched specimens is not uncommon, only the overall preservation of the assemblage is recorded in Tables T1, T2, T3, and T4. The overall preservation of the nannofossil assemblages in this paper was determined as follows:
Upper Quaternary marker species were verified using a scanning electron microscope (SEM). Samples for the SEM were prepared according to the settling technique of de Kaenel and Bergen (1996), dried directly onto a specimen stub, and viewed with a JEOL SEM.
Calcareous nannofossil species considered in this paper are listed in the "Appendix," where they are arranged alphabetically by generic epithet with some additional taxonomic notes. Bibliographic references for these taxa can be found in Perch-Nielsen (1985) and Bown (1999). Key marker species were photographed under the light microscope and digital SEM for taxonomic clarity (Pl. P1).
At each Leg 189 site, Quaternary sediments were recovered in three holes using the advanced piston coring system. Composite sections between the three holes were created by stratigraphic correlation of multisensor track data (Shipboard Scientific Party, 2001b, 2001d, 2001e, 2001f). The composite sections extended through the Quaternary sediments; therefore, sediments from only one hole at each site were analyzed for this study.
Core disturbance was determined by examining core photos (Exon, Kennett, Malone, et al., 2001) and applying the relative disturbance scale (0–5) developed by shipboard sedimentologists (Shipboard Scientific Party, 2001a). Aboard ship, the disturbance scale was used to create a graphic representation of the intensity of the core disturbance primarily at the core (9 m) scale. The disturbance representation for this study was constructed on a 10-cm scale to reflect in detail the condition of the cores studied. The disturbance scale does not differentiate between natural processes (i.e., bioturbation, slumps, etc.) and coring processes (i.e., flow-in, shattered core-liners, etc.) that are responsible for the conditions of the core.
Reworking of nannofossils was noted at all study sites. Reworking of obviously time-transgressive nannofossils was easily spotted; however, identification of reworked Pleistocene nannofossils required careful observation of their preservational state. The preservation of suspect nannofossils was compared to other assemblage nannofossils as well as the same species in adjacent samples. As the preservation was good or moderate, this method was generally useful in identifying reworked Pleistocene nannofossils within the studied sections without requiring quantitative techniques.